diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_Bindings/Reducer_Bindings_test.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_Bindings/Reducer_Bindings_test.res
index f43944d4..c386d343 100644
--- a/packages/squiggle-lang/__tests__/Reducer/Reducer_Bindings/Reducer_Bindings_test.res
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_Bindings/Reducer_Bindings_test.res
@@ -31,9 +31,7 @@ describe("Bindings", () => {
 
   describe("extend", () => {
     let value2 = Reducer_T.IEvNumber(5.)
-    let extendedBindings = bindings
-      ->Bindings.extend
-      ->Bindings.set("value", value2)
+    let extendedBindings = bindings->Bindings.extend->Bindings.set("value", value2)
 
     test("get on extended", () => {
       expect(extendedBindings->Bindings.get("value")) == Some(value2)
diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltInMacros_test.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltInMacros_test.res
index 7e667acd..71b9c86d 100644
--- a/packages/squiggle-lang/__tests__/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltInMacros_test.res
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltInMacros_test.res
@@ -144,3 +144,4 @@
 //   let callLambdaExpression = eList(list{lambdaExpression, eNumber(1.)})
 //   testMacroEval([("y", IEvNumber(666.))], callLambdaExpression, "Ok(667)")
 // })
+
diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_Namespace_test.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_Namespace_test.res
index 64401e32..e745dc64 100644
--- a/packages/squiggle-lang/__tests__/Reducer/Reducer_Namespace_test.res
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_Namespace_test.res
@@ -35,13 +35,9 @@ describe("Namespace", () => {
     let x2 = makeValue(20.)
     let x3 = makeValue(30.)
     let x4 = makeValue(40.)
-    let ns1 = Namespace.make()
-        ->Namespace.set("x1", x1)
-        ->Namespace.set("x2", x2)
-    let ns2 = Namespace.make()
-        ->Namespace.set("x3", x3)
-        ->Namespace.set("x4", x4)
-    
+    let ns1 = Namespace.make()->Namespace.set("x1", x1)->Namespace.set("x2", x2)
+    let ns2 = Namespace.make()->Namespace.set("x3", x3)->Namespace.set("x4", x4)
+
     let nsMerged = Namespace.mergeMany([ns, ns1, ns2])
 
     test("merge many 1", () => {
diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_Parse_test.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_Parse_test.res
index 416e0178..6c60c187 100644
--- a/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_Parse_test.res
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_Parse_test.res
@@ -38,58 +38,22 @@ describe("Peggy parse", () => {
     testParse("1 * 2 / 3", "{(:divide (:multiply 1 2) 3)}")
     testParse("1 / 2 * 3", "{(:multiply (:divide 1 2) 3)}")
     testParse("1 / 2 / 3", "{(:divide (:divide 1 2) 3)}")
-    testParse(
-      "1 * 2 + 3 * 4",
-      "{(:add (:multiply 1 2) (:multiply 3 4))}",
-    )
-    testParse(
-      "1 * 2 - 3 * 4",
-      "{(:subtract (:multiply 1 2) (:multiply 3 4))}",
-    )
-    testParse(
-      "1 * 2 .+ 3 * 4",
-      "{(:dotAdd (:multiply 1 2) (:multiply 3 4))}",
-    )
-    testParse(
-      "1 * 2 .- 3 * 4",
-      "{(:dotSubtract (:multiply 1 2) (:multiply 3 4))}",
-    )
-    testParse(
-      "1 * 2 + 3 .* 4",
-      "{(:add (:multiply 1 2) (:dotMultiply 3 4))}",
-    )
-    testParse(
-      "1 * 2 + 3 / 4",
-      "{(:add (:multiply 1 2) (:divide 3 4))}",
-    )
-    testParse(
-      "1 * 2 + 3 ./ 4",
-      "{(:add (:multiply 1 2) (:dotDivide 3 4))}",
-    )
-    testParse(
-      "1 * 2 - 3 .* 4",
-      "{(:subtract (:multiply 1 2) (:dotMultiply 3 4))}",
-    )
-    testParse(
-      "1 * 2 - 3 / 4",
-      "{(:subtract (:multiply 1 2) (:divide 3 4))}",
-    )
-    testParse(
-      "1 * 2 - 3 ./ 4",
-      "{(:subtract (:multiply 1 2) (:dotDivide 3 4))}",
-    )
-    testParse(
-      "1 * 2 - 3 * 4^5",
-      "{(:subtract (:multiply 1 2) (:multiply 3 (:pow 4 5)))}",
-    )
+    testParse("1 * 2 + 3 * 4", "{(:add (:multiply 1 2) (:multiply 3 4))}")
+    testParse("1 * 2 - 3 * 4", "{(:subtract (:multiply 1 2) (:multiply 3 4))}")
+    testParse("1 * 2 .+ 3 * 4", "{(:dotAdd (:multiply 1 2) (:multiply 3 4))}")
+    testParse("1 * 2 .- 3 * 4", "{(:dotSubtract (:multiply 1 2) (:multiply 3 4))}")
+    testParse("1 * 2 + 3 .* 4", "{(:add (:multiply 1 2) (:dotMultiply 3 4))}")
+    testParse("1 * 2 + 3 / 4", "{(:add (:multiply 1 2) (:divide 3 4))}")
+    testParse("1 * 2 + 3 ./ 4", "{(:add (:multiply 1 2) (:dotDivide 3 4))}")
+    testParse("1 * 2 - 3 .* 4", "{(:subtract (:multiply 1 2) (:dotMultiply 3 4))}")
+    testParse("1 * 2 - 3 / 4", "{(:subtract (:multiply 1 2) (:divide 3 4))}")
+    testParse("1 * 2 - 3 ./ 4", "{(:subtract (:multiply 1 2) (:dotDivide 3 4))}")
+    testParse("1 * 2 - 3 * 4^5", "{(:subtract (:multiply 1 2) (:multiply 3 (:pow 4 5)))}")
     testParse(
       "1 * 2 - 3 * 4^5^6",
       "{(:subtract (:multiply 1 2) (:multiply 3 (:pow (:pow 4 5) 6)))}",
     )
-    testParse(
-      "1 * -a[-2]",
-      "{(:multiply 1 (:unaryMinus (:$_atIndex_$ :a (:unaryMinus 2))))}",
-    )
+    testParse("1 * -a[-2]", "{(:multiply 1 (:unaryMinus (:$_atIndex_$ :a (:unaryMinus 2))))}")
   })
 
   describe("multi-line", () => {
@@ -111,25 +75,13 @@ describe("Peggy parse", () => {
   describe("arrays", () => {
     testParse("[]", "{[]}")
     testParse("[0, 1, 2]", "{[0; 1; 2]}")
-    testParse(
-      "['hello', 'world']",
-      "{['hello'; 'world']}",
-    )
-    testParse(
-      "([0,1,2])[1]",
-      "{(:$_atIndex_$ [0; 1; 2] 1)}",
-    )
+    testParse("['hello', 'world']", "{['hello'; 'world']}")
+    testParse("([0,1,2])[1]", "{(:$_atIndex_$ [0; 1; 2] 1)}")
   })
 
   describe("records", () => {
-    testParse(
-      "{a: 1, b: 2}",
-      "{{'a': 1, 'b': 2}}",
-    )
-    testParse(
-      "{1+0: 1, 2+0: 2}",
-      "{{(:add 1 0): 1, (:add 2 0): 2}}",
-    ) // key can be any expression
+    testParse("{a: 1, b: 2}", "{{'a': 1, 'b': 2}}")
+    testParse("{1+0: 1, 2+0: 2}", "{{(:add 1 0): 1, (:add 2 0): 2}}") // key can be any expression
     testParse("record.property", "{(:$_atIndex_$ :record 'property')}")
   })
 
@@ -137,10 +89,7 @@ describe("Peggy parse", () => {
     //function call, array and record access are post operators with higher priority than unary operators
     testParse("a==!b(1)", "{(:equal :a (:not (:b 1)))}")
     testParse("a==!b[1]", "{(:equal :a (:not (:$_atIndex_$ :b 1)))}")
-    testParse(
-      "a==!b.one",
-      "{(:equal :a (:not (:$_atIndex_$ :b 'one')))}",
-    )
+    testParse("a==!b.one", "{(:equal :a (:not (:$_atIndex_$ :b 'one')))}")
   })
 
   describe("comments", () => {
@@ -167,14 +116,8 @@ describe("Peggy parse", () => {
   })
 
   describe("if then else", () => {
-    testParse(
-      "if true then 2 else 3",
-      "{(::$$_ternary_$$ true {2} {3})}",
-    )
-    testParse(
-      "if false then {2} else {3}",
-      "{(::$$_ternary_$$ false {2} {3})}",
-    )
+    testParse("if true then 2 else 3", "{(::$$_ternary_$$ true {2} {3})}")
+    testParse("if false then {2} else {3}", "{(::$$_ternary_$$ false {2} {3})}")
     testParse(
       "if false then {2} else if false then {4} else {5}",
       "{(::$$_ternary_$$ false {2} (::$$_ternary_$$ false {4} {5}))}",
@@ -189,51 +132,18 @@ describe("Peggy parse", () => {
     testParse("a && b || c && d", "{(:or (:and :a :b) (:and :c :d))}")
     testParse("a && !b || c", "{(:or (:and :a (:not :b)) :c)}")
     testParse("a && b==c || d", "{(:or (:and :a (:equal :b :c)) :d)}")
-    testParse(
-      "a && b!=c || d",
-      "{(:or (:and :a (:unequal :b :c)) :d)}",
-    )
-    testParse(
-      "a && !(b==c) || d",
-      "{(:or (:and :a (:not (:equal :b :c))) :d)}",
-    )
-    testParse(
-      "a && b>=c || d",
-      "{(:or (:and :a (:largerEq :b :c)) :d)}",
-    )
-    testParse(
-      "a && !(b>=c) || d",
-      "{(:or (:and :a (:not (:largerEq :b :c))) :d)}",
-    )
-    testParse(
-      "a && b<=c || d",
-      "{(:or (:and :a (:smallerEq :b :c)) :d)}",
-    )
+    testParse("a && b!=c || d", "{(:or (:and :a (:unequal :b :c)) :d)}")
+    testParse("a && !(b==c) || d", "{(:or (:and :a (:not (:equal :b :c))) :d)}")
+    testParse("a && b>=c || d", "{(:or (:and :a (:largerEq :b :c)) :d)}")
+    testParse("a && !(b>=c) || d", "{(:or (:and :a (:not (:largerEq :b :c))) :d)}")
+    testParse("a && b<=c || d", "{(:or (:and :a (:smallerEq :b :c)) :d)}")
     testParse("a && b>c || d", "{(:or (:and :a (:larger :b :c)) :d)}")
-    testParse(
-      "a && b<c || d",
-      "{(:or (:and :a (:smaller :b :c)) :d)}",
-    )
-    testParse(
-      "a && b<c[i] || d",
-      "{(:or (:and :a (:smaller :b (:$_atIndex_$ :c :i))) :d)}",
-    )
-    testParse(
-      "a && b<c.i || d",
-      "{(:or (:and :a (:smaller :b (:$_atIndex_$ :c 'i'))) :d)}",
-    )
-    testParse(
-      "a && b<c(i) || d",
-      "{(:or (:and :a (:smaller :b (:c :i))) :d)}",
-    )
-    testParse(
-      "a && b<1+2 || d",
-      "{(:or (:and :a (:smaller :b (:add 1 2))) :d)}",
-    )
-    testParse(
-      "a && b<1+2*3 || d",
-      "{(:or (:and :a (:smaller :b (:add 1 (:multiply 2 3)))) :d)}",
-    )
+    testParse("a && b<c || d", "{(:or (:and :a (:smaller :b :c)) :d)}")
+    testParse("a && b<c[i] || d", "{(:or (:and :a (:smaller :b (:$_atIndex_$ :c :i))) :d)}")
+    testParse("a && b<c.i || d", "{(:or (:and :a (:smaller :b (:$_atIndex_$ :c 'i'))) :d)}")
+    testParse("a && b<c(i) || d", "{(:or (:and :a (:smaller :b (:c :i))) :d)}")
+    testParse("a && b<1+2 || d", "{(:or (:and :a (:smaller :b (:add 1 2))) :d)}")
+    testParse("a && b<1+2*3 || d", "{(:or (:and :a (:smaller :b (:add 1 (:multiply 2 3)))) :d)}")
     testParse(
       "a && b<1+2*-3+4 || d",
       "{(:or (:and :a (:smaller :b (:add (:add 1 (:multiply 2 (:unaryMinus 3))) 4))) :d)}",
@@ -247,19 +157,13 @@ describe("Peggy parse", () => {
   describe("pipe", () => {
     testParse("1 -> add(2)", "{(:add 1 2)}")
     testParse("-1 -> add(2)", "{(:add (:unaryMinus 1) 2)}")
-    testParse(
-      "-a[1] -> add(2)",
-      "{(:add (:unaryMinus (:$_atIndex_$ :a 1)) 2)}",
-    )
+    testParse("-a[1] -> add(2)", "{(:add (:unaryMinus (:$_atIndex_$ :a 1)) 2)}")
     testParse("-f(1) -> add(2)", "{(:add (:unaryMinus (:f 1)) 2)}")
     testParse("1 + 2 -> add(3)", "{(:add 1 (:add 2 3))}")
     testParse("1 -> add(2) * 3", "{(:multiply (:add 1 2) 3)}")
     testParse("1 -> subtract(2)", "{(:subtract 1 2)}")
     testParse("-1 -> subtract(2)", "{(:subtract (:unaryMinus 1) 2)}")
-    testParse(
-      "1 -> subtract(2) * 3",
-      "{(:multiply (:subtract 1 2) 3)}",
-    )
+    testParse("1 -> subtract(2) * 3", "{(:multiply (:subtract 1 2) 3)}")
   })
 
   describe("elixir pipe", () => {
@@ -269,10 +173,7 @@ describe("Peggy parse", () => {
 
   describe("to", () => {
     testParse("1 to 2", "{(:credibleIntervalToDistribution 1 2)}")
-    testParse(
-      "-1 to -2",
-      "{(:credibleIntervalToDistribution (:unaryMinus 1) (:unaryMinus 2))}",
-    ) // lower than unary
+    testParse("-1 to -2", "{(:credibleIntervalToDistribution (:unaryMinus 1) (:unaryMinus 2))}") // lower than unary
     testParse(
       "a[1] to a[2]",
       "{(:credibleIntervalToDistribution (:$_atIndex_$ :a 1) (:$_atIndex_$ :a 2))}",
@@ -281,10 +182,7 @@ describe("Peggy parse", () => {
       "a.p1 to a.p2",
       "{(:credibleIntervalToDistribution (:$_atIndex_$ :a 'p1') (:$_atIndex_$ :a 'p2'))}",
     ) // lower than post
-    testParse(
-      "1 to 2 + 3",
-      "{(:add (:credibleIntervalToDistribution 1 2) 3)}",
-    ) // higher than binary operators
+    testParse("1 to 2 + 3", "{(:add (:credibleIntervalToDistribution 1 2) 3)}") // higher than binary operators
     testParse(
       "1->add(2) to 3->add(4) -> add(4)",
       "{(:credibleIntervalToDistribution (:add 1 2) (:add (:add 3 4) 4))}",
@@ -301,10 +199,7 @@ describe("Peggy parse", () => {
     testParse("{|x| x}", "{{|:x| :x}}")
     testParse("f={|x| x}", "{:f = {{|:x| :x}}}")
     testParse("f(x)=x", "{:f = {|:x| {:x}}}") // Function definitions are lambda assignments
-    testParse(
-      "f(x)=x ? 1 : 0",
-      "{:f = {|:x| {(::$$_ternary_$$ :x 1 0)}}}",
-    ) // Function definitions are lambda assignments
+    testParse("f(x)=x ? 1 : 0", "{:f = {|:x| {(::$$_ternary_$$ :x 1 0)}}}") // Function definitions are lambda assignments
   })
 
   describe("Using lambda as value", () => {
@@ -321,18 +216,9 @@ describe("Peggy parse", () => {
       "{:myaddd = {|:x,:y| {(:add :x :y)}}; :z = {{'x': :myaddd}}; :z}",
     )
     testParse("f({|x| x+1})", "{(:f {|:x| (:add :x 1)})}")
-    testParse(
-      "map(arr, {|x| x+1})",
-      "{(:map :arr {|:x| (:add :x 1)})}",
-    )
-    testParse(
-      "map([1,2,3], {|x| x+1})",
-      "{(:map [1; 2; 3] {|:x| (:add :x 1)})}",
-    )
-    testParse(
-      "[1,2,3]->map({|x| x+1})",
-      "{(:map [1; 2; 3] {|:x| (:add :x 1)})}",
-    )
+    testParse("map(arr, {|x| x+1})", "{(:map :arr {|:x| (:add :x 1)})}")
+    testParse("map([1,2,3], {|x| x+1})", "{(:map [1; 2; 3] {|:x| (:add :x 1)})}")
+    testParse("[1,2,3]->map({|x| x+1})", "{(:map [1; 2; 3] {|:x| (:add :x 1)})}")
   })
   describe("unit", () => {
     testParse("1m", "{(:fromUnit_m 1)}")
@@ -419,7 +305,7 @@ describe("parsing new line", () => {
  g=f+4
  g
  `,
-    "{:f = {:x = {1}; :y = {2}; :z = {3}; (:add (:add :x :y) :z)}; :g = {(:add :f 4)}; :g}"
+    "{:f = {:x = {1}; :y = {2}; :z = {3}; (:add (:add :x :y) :z)}; :g = {(:add :f 4)}; :g}",
   )
   testParse(
     `
@@ -441,7 +327,7 @@ describe("parsing new line", () => {
   p ->
   q 
  `,
-    "{:f = {:x = {1}; :y = {2}; :z = {3}; (:add (:add :x :y) :z)}; :g = {(:add :f 4)}; (:q (:p (:h :g)))}"
+    "{:f = {:x = {1}; :y = {2}; :z = {3}; (:add (:add :x :y) :z)}; :g = {(:add :f 4)}; (:q (:p (:h :g)))}",
   )
   testParse(
     `
@@ -460,6 +346,6 @@ describe("parsing new line", () => {
   d +
   e
  `,
-    "{(:add (:d (:c (:b :a))) :e)}"
+    "{(:add (:d (:c (:b :a))) :e)}",
   )
 })
diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_outerBlock_test.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_outerBlock_test.res
index bcc99bfb..03ef24c8 100644
--- a/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_outerBlock_test.res
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_outerBlock_test.res
@@ -4,20 +4,12 @@ module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 open Jest
 open Reducer_Peggy_TestHelpers
 
+// Note: these tests aren't useful anymore since outer block macro got deleted.
+// Probably can be removed or folded into other Peggy tests.
 describe("Peggy Outer Block", () => {
   testToExpression("1", "1", ~v="1", ())
   testToExpression("x=1", "x = {1}", ~v="()", ())
-  testToExpression(
-    "x=1; y=2",
-    "x = {1}; y = {2}",
-    ~v="()",
-    (),
-  )
+  testToExpression("x=1; y=2", "x = {1}; y = {2}", ~v="()", ())
   testToExpression("x=1; 2", "x = {1}; 2", ~v="2", ())
-  testToExpression(
-    "x={a=1; a}; x",
-    "x = {a = {1}; a}; x",
-    ~v="1",
-    (),
-  )
+  testToExpression("x={a=1; a}; x", "x = {a = {1}; a}; x", ~v="1", ())
 })
diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_test.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_test.res
index d2e64393..3016e3c2 100644
--- a/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_test.res
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_test.res
@@ -25,11 +25,7 @@ describe("Peggy to Expression", () => {
 
   describe("multi-line", () => {
     testToExpression("x=1; 2", "x = {1}; 2", ~v="2", ())
-    testToExpression(
-      "x=1; y=2",
-      "x = {1}; y = {2}",
-      (),
-    )
+    testToExpression("x=1; y=2", "x = {1}; y = {2}", ())
   })
 
   describe("variables", () => {
@@ -39,11 +35,7 @@ describe("Peggy to Expression", () => {
   })
 
   describe("functions", () => {
-    testToExpression(
-      "identity(x) = x",
-      "identity = {|x| {x}}",
-      (),
-    ) // Function definitions become lambda assignments
+    testToExpression("identity(x) = x", "identity = {|x| {x}}", ()) // Function definitions become lambda assignments
     testToExpression("identity(x)", "(identity)(x)", ()) // Note value returns error properly
     testToExpression(
       "f(x) = x> 2 ? 0 : 1; f(3)",
@@ -55,43 +47,15 @@ describe("Peggy to Expression", () => {
 
   describe("arrays", () => {
     testToExpression("[]", "[]", ~v="[]", ())
-    testToExpression(
-      "[0, 1, 2]",
-      "[0, 1, 2]",
-      ~v="[0,1,2]",
-      (),
-    )
-    testToExpression(
-      "['hello', 'world']",
-      "['hello', 'world']",
-      ~v="['hello','world']",
-      (),
-    )
-    testToExpression(
-      "([0,1,2])[1]",
-      "($_atIndex_$)([0, 1, 2], 1)",
-      ~v="1",
-      (),
-    )
+    testToExpression("[0, 1, 2]", "[0, 1, 2]", ~v="[0,1,2]", ())
+    testToExpression("['hello', 'world']", "['hello', 'world']", ~v="['hello','world']", ())
+    testToExpression("([0,1,2])[1]", "($_atIndex_$)([0, 1, 2], 1)", ~v="1", ())
   })
 
   describe("records", () => {
-    testToExpression(
-      "{a: 1, b: 2}",
-      "{'a': 1, 'b': 2}",
-      ~v="{a: 1,b: 2}",
-      (),
-    )
-    testToExpression(
-      "{1+0: 1, 2+0: 2}",
-      "{(add)(1, 0): 1, (add)(2, 0): 2}",
-      (),
-    ) // key can be any expression
-    testToExpression(
-      "record.property",
-      "($_atIndex_$)(record, 'property')",
-      (),
-    )
+    testToExpression("{a: 1, b: 2}", "{'a': 1, 'b': 2}", ~v="{a: 1,b: 2}", ())
+    testToExpression("{1+0: 1, 2+0: 2}", "{(add)(1, 0): 1, (add)(2, 0): 2}", ()) // key can be any expression
+    testToExpression("record.property", "($_atIndex_$)(record, 'property')", ())
     testToExpression(
       "record={property: 1}; record.property",
       "record = {{'property': 1}}; ($_atIndex_$)(record, 'property')",
@@ -103,45 +67,15 @@ describe("Peggy to Expression", () => {
   describe("comments", () => {
     testToExpression("1 # This is a line comment", "1", ~v="1", ())
     testToExpression("1 // This is a line comment", "1", ~v="1", ())
-    testToExpression(
-      "1 /* This is a multi line comment */",
-      "1",
-      ~v="1",
-      (),
-    )
-    testToExpression(
-      "/* This is a multi line comment */ 1",
-      "1",
-      ~v="1",
-      (),
-    )
+    testToExpression("1 /* This is a multi line comment */", "1", ~v="1", ())
+    testToExpression("/* This is a multi line comment */ 1", "1", ~v="1", ())
   })
 
   describe("ternary operator", () => {
-    testToExpression(
-      "true ? 1 : 0",
-      "true ? (1) : (0)",
-      ~v="1",
-      (),
-    )
-    testToExpression(
-      "false ? 1 : 0",
-      "false ? (1) : (0)",
-      ~v="0",
-      (),
-    )
-    testToExpression(
-      "true ? 1 : false ? 2 : 0",
-      "true ? (1) : (false ? (2) : (0))",
-      ~v="1",
-      (),
-    ) // nested ternary
-    testToExpression(
-      "false ? 1 : false ? 2 : 0",
-      "false ? (1) : (false ? (2) : (0))",
-      ~v="0",
-      (),
-    ) // nested ternary
+    testToExpression("true ? 1 : 0", "true ? (1) : (0)", ~v="1", ())
+    testToExpression("false ? 1 : 0", "false ? (1) : (0)", ~v="0", ())
+    testToExpression("true ? 1 : false ? 2 : 0", "true ? (1) : (false ? (2) : (0))", ~v="1", ()) // nested ternary
+    testToExpression("false ? 1 : false ? 2 : 0", "false ? (1) : (false ? (2) : (0))", ~v="0", ()) // nested ternary
     describe("ternary bindings", () => {
       testToExpression(
         // expression binding
@@ -168,16 +102,8 @@ describe("Peggy to Expression", () => {
   })
 
   describe("if then else", () => {
-    testToExpression(
-      "if true then 2 else 3",
-      "true ? ({2}) : ({3})",
-      (),
-    )
-    testToExpression(
-      "if true then {2} else {3}",
-      "true ? ({2}) : ({3})",
-      (),
-    )
+    testToExpression("if true then 2 else 3", "true ? ({2}) : ({3})", ())
+    testToExpression("if true then {2} else {3}", "true ? ({2}) : ({3})", ())
     testToExpression(
       "if false then {2} else if false then {4} else {5}",
       "false ? ({2}) : (false ? ({4}) : ({5}))",
@@ -187,18 +113,8 @@ describe("Peggy to Expression", () => {
 
   describe("pipe", () => {
     testToExpression("1 -> add(2)", "(add)(1, 2)", ~v="3", ())
-    testToExpression(
-      "-1 -> add(2)",
-      "(add)((unaryMinus)(1), 2)",
-      ~v="1",
-      (),
-    ) // note that unary has higher priority naturally
-    testToExpression(
-      "1 -> add(2) * 3",
-      "(multiply)((add)(1, 2), 3)",
-      ~v="9",
-      (),
-    )
+    testToExpression("-1 -> add(2)", "(add)((unaryMinus)(1), 2)", ~v="1", ()) // note that unary has higher priority naturally
+    testToExpression("1 -> add(2) * 3", "(multiply)((add)(1, 2), 3)", ~v="9", ())
   })
 
   describe("elixir pipe", () => {
@@ -219,27 +135,10 @@ describe("Peggy to Expression", () => {
   })
 
   describe("lambda", () => {
-    testToExpression(
-      "{|x| x}",
-      "{|x| x}",
-      ~v="lambda(x=>internal code)",
-      (),
-    )
-    testToExpression(
-      "f={|x| x}",
-      "f = {{|x| x}}",
-      (),
-    )
-    testToExpression(
-      "f(x)=x",
-      "f = {|x| {x}}",
-      (),
-    ) // Function definitions are lambda assignments
-    testToExpression(
-      "f(x)=x ? 1 : 0",
-      "f = {|x| {x ? (1) : (0)}}",
-      (),
-    )
+    testToExpression("{|x| x}", "{|x| x}", ~v="lambda(x=>internal code)", ())
+    testToExpression("f={|x| x}", "f = {{|x| x}}", ())
+    testToExpression("f(x)=x", "f = {|x| {x}}", ()) // Function definitions are lambda assignments
+    testToExpression("f(x)=x ? 1 : 0", "f = {|x| {x ? (1) : (0)}}", ())
   })
 
   describe("module", () => {
diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_TestMacroHelpers.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_TestMacroHelpers.res
index a8c9717e..c69d060c 100644
--- a/packages/squiggle-lang/__tests__/Reducer/Reducer_TestMacroHelpers.res
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_TestMacroHelpers.res
@@ -86,3 +86,4 @@
 //     expectedValue: string,
 //   ) => testMacroEval_(Only.test, bindArray, expr, expectedValue)
 // }
+
diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_Compile_test.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_Compile_test.res
index 7d3ab86b..8abf5f7a 100644
--- a/packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_Compile_test.res
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_Compile_test.res
@@ -50,3 +50,4 @@
 //   "Ok({properties: {age: #number,name: #string},typeTag: 'typeRecord'})",
 // )
 // myTypeTest(test, "{age: number, name: string}", "{age: number, name: string}")
+
diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_TypeChecker_arguments_test.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_TypeChecker_arguments_test.res
index be20c5fd..64f2554a 100644
--- a/packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_TypeChecker_arguments_test.res
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_TypeChecker_arguments_test.res
@@ -40,3 +40,4 @@
 //   test(aTypeSourceCode, () => myCheckArgumentsExpectEqual(aTypeSourceCode, sourceCode, answer))
 
 // myCheckArgumentsTest(test, "number=>number=>number", "[1,2]", "Ok")
+
diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_TypeChecker_test.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_TypeChecker_test.res
index f935c7b0..c4272880 100644
--- a/packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_TypeChecker_test.res
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_TypeChecker_test.res
@@ -71,3 +71,4 @@
 // myTypeCheckTest(test, "number<-min(10)", "0", "Expected type: number<-min(10) but got: 0")
 // myTypeCheckTest(test, "any", "0", "Ok")
 // myTypeCheckTest(test, "any", "'a'", "Ok")
+
diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_switch_replacement_test.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_switch_replacement_test.res
index 27fe6fce..88f3d9a6 100644
--- a/packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_switch_replacement_test.res
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_switch_replacement_test.res
@@ -124,3 +124,4 @@
 //     expect(result)->toEqual(Some(Ok(IEvString("helloworld"))))
 //   })
 // })
+
diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_functionAssignment_test.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_functionAssignment_test.res
index 52f8329b..e48d1223 100644
--- a/packages/squiggle-lang/__tests__/Reducer/Reducer_functionAssignment_test.res
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_functionAssignment_test.res
@@ -2,14 +2,8 @@ open Jest
 open Reducer_TestHelpers
 
 describe("Parse function assignment", () => {
-  testParseToBe(
-    "f(x)=x",
-    "Ok(f = {|x| {x}})"
-  )
-  testParseToBe(
-    "f(x)=2*x",
-    "Ok(f = {|x| {(multiply)(2, x)}})"
-  )
+  testParseToBe("f(x)=x", "Ok(f = {|x| {x}})")
+  testParseToBe("f(x)=2*x", "Ok(f = {|x| {(multiply)(2, x)}})")
   //MathJs does not allow blocks in function definitions
 })
 
diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_functionTricks_test.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_functionTricks_test.res
index 8045d0d2..14f7f380 100644
--- a/packages/squiggle-lang/__tests__/Reducer/Reducer_functionTricks_test.res
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_functionTricks_test.res
@@ -46,10 +46,7 @@ describe("call and bindings", () => {
   testEvalToBe("f(x)=x+1; y=f(1); f(1)", "Ok(2)")
   testEvalToBe("f(x)=x+1; y=f(1); z=f(1); z", "Ok(2)")
   testEvalToBe("f(x)=x+1; g(x)=f(x)+1; g(0)", "Ok(2)")
-  testParseToBe(
-    "f=99; g(x)=f; g(2)",
-    "Ok(f = {99}; g = {|x| {f}}; (g)(2))",
-  )
+  testParseToBe("f=99; g(x)=f; g(2)", "Ok(f = {99}; g = {|x| {f}}; (g)(2))")
   testEvalToBe("f=99; g(x)=f; g(2)", "Ok(99)")
   testEvalToBe("f(x)=x; g(x)=f(x); g(2)", "Ok(2)")
   testEvalToBe("f(x)=x+1; g(x)=f(x)+1; y=g(2); y", "Ok(4)")
diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_ternaryOperator_test.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_ternaryOperator_test.res
index 3f66649b..e157ccbf 100644
--- a/packages/squiggle-lang/__tests__/Reducer/Reducer_ternaryOperator_test.res
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_ternaryOperator_test.res
@@ -2,10 +2,7 @@ open Jest
 open Reducer_TestHelpers
 
 describe("Parse ternary operator", () => {
-  testParseToBe(
-    "true ? 'YES' : 'NO'",
-    "Ok(true ? ('YES') : ('NO'))",
-  )
+  testParseToBe("true ? 'YES' : 'NO'", "Ok(true ? ('YES') : ('NO'))")
 })
 
 describe("Evaluate ternary operator", () => {
diff --git a/packages/squiggle-lang/__tests__/ReducerInterface/ReducerInterface_Distribution_test.res b/packages/squiggle-lang/__tests__/ReducerInterface/ReducerInterface_Distribution_test.res
index 21a0e9c3..78d3f900 100644
--- a/packages/squiggle-lang/__tests__/ReducerInterface/ReducerInterface_Distribution_test.res
+++ b/packages/squiggle-lang/__tests__/ReducerInterface/ReducerInterface_Distribution_test.res
@@ -119,10 +119,7 @@ describe("eval on distribution functions", () => {
 
 describe("parse on distribution functions", () => {
   describe("power", () => {
-    testParse(
-      "normal(5,2) ^ normal(5,1)",
-      "Ok((pow)((normal)(5, 2), (normal)(5, 1)))",
-    )
+    testParse("normal(5,2) ^ normal(5,1)", "Ok((pow)((normal)(5, 2), (normal)(5, 1)))")
     testParse("3 ^ normal(5,1)", "Ok((pow)(3, (normal)(5, 1)))")
     testParse("normal(5,2) ^ 3", "Ok((pow)((normal)(5, 2), 3))")
   })
@@ -138,18 +135,9 @@ describe("parse on distribution functions", () => {
       "Ok((:$$_block_$$ (:dotSubtract (:normal 5 2) (:normal 5 1))))",
       // TODO: !!! returns "Ok({(:dotPow (:normal 5 2) (:normal 5 1))})"
     )
-    testParse(
-      "normal(5,2) .* normal(5,1)",
-      "Ok((dotMultiply)((normal)(5, 2), (normal)(5, 1)))",
-    )
-    testParse(
-      "normal(5,2) ./ normal(5,1)",
-      "Ok((dotDivide)((normal)(5, 2), (normal)(5, 1)))",
-    )
-    testParse(
-      "normal(5,2) .^ normal(5,1)",
-      "Ok((dotPow)((normal)(5, 2), (normal)(5, 1)))",
-    )
+    testParse("normal(5,2) .* normal(5,1)", "Ok((dotMultiply)((normal)(5, 2), (normal)(5, 1)))")
+    testParse("normal(5,2) ./ normal(5,1)", "Ok((dotDivide)((normal)(5, 2), (normal)(5, 1)))")
+    testParse("normal(5,2) .^ normal(5,1)", "Ok((dotPow)((normal)(5, 2), (normal)(5, 1)))")
   })
   describe("equality", () => {
     testParse("5 == normal(5,2)", "Ok((equal)(5, (normal)(5, 2)))")
diff --git a/packages/squiggle-lang/__tests__/ReducerProject/ReducerProject_includes_test.res b/packages/squiggle-lang/__tests__/ReducerProject/ReducerProject_includes_test.res
index 3097d74a..3d1fcddc 100644
--- a/packages/squiggle-lang/__tests__/ReducerProject/ReducerProject_includes_test.res
+++ b/packages/squiggle-lang/__tests__/ReducerProject/ReducerProject_includes_test.res
@@ -75,9 +75,7 @@ x=1`,
   })
 
   test("include as variables", () => {
-    expect(project->Project.Private.getIncludesAsVariables("main")) == [
-        ("myVariable", "myModule"),
-      ]
+    expect(project->Project.Private.getIncludesAsVariables("main")) == [("myVariable", "myModule")]
   })
 })
 
@@ -110,8 +108,6 @@ x=1`,
     expect(Project.getPastChain(project, "main")) == ["common", "common2"]
   })
   test("include as variables", () => {
-    expect(project->Project.Private.getIncludesAsVariables("main")) == [
-        ("myVariable", "myModule"),
-      ]
+    expect(project->Project.Private.getIncludesAsVariables("main")) == [("myVariable", "myModule")]
   })
 })
diff --git a/packages/squiggle-lang/__tests__/ReducerProject/ReducerProject_test.res b/packages/squiggle-lang/__tests__/ReducerProject/ReducerProject_test.res
index ccda4b4f..d85d636c 100644
--- a/packages/squiggle-lang/__tests__/ReducerProject/ReducerProject_test.res
+++ b/packages/squiggle-lang/__tests__/ReducerProject/ReducerProject_test.res
@@ -14,8 +14,7 @@ let runFetchResult = (project, sourceId) => {
 
 let runFetchFlatBindings = (project, sourceId) => {
   Project.run(project, sourceId)
-  Project.getBindings(project, sourceId)
-  ->InternalExpressionValue.toStringRecord
+  Project.getBindings(project, sourceId)->InternalExpressionValue.toStringRecord
 }
 
 test("test result true", () => {
diff --git a/packages/squiggle-lang/benchmark/Benchmark_Array.res b/packages/squiggle-lang/benchmark/Benchmark_Array.res
index 61562732..268fea01 100644
--- a/packages/squiggle-lang/benchmark/Benchmark_Array.res
+++ b/packages/squiggle-lang/benchmark/Benchmark_Array.res
@@ -24,7 +24,9 @@ module Map: Benchmark_Helpers.BenchmarkTopic = {
   }
 
   let runAll = () => {
-    Js.log(`Mapping identity function over arrays of size ${arraySize->Js.Int.toString} (${iterations->Js.Int.toString} iterations)`)
+    Js.log(
+      `Mapping identity function over arrays of size ${arraySize->Js.Int.toString} (${iterations->Js.Int.toString} iterations)`,
+    )
     Benchmark_Helpers.measure("Belt.Array.map", beltArray)
     Benchmark_Helpers.measure("Js.Array2.map", jsArray2)
     Benchmark_Helpers.measure("Array.map", ocamlArray)
@@ -65,7 +67,9 @@ module Sort: Benchmark_Helpers.BenchmarkTopic = {
   }
 
   let runAll = () => {
-    Js.log(`Sorting arrays of size ${arraySize->Js.Int.toString} (${iterations->Js.Int.toString} iterations)`)
+    Js.log(
+      `Sorting arrays of size ${arraySize->Js.Int.toString} (${iterations->Js.Int.toString} iterations)`,
+    )
     Benchmark_Helpers.measure("Js.Array2.sort", jsArray2)
     Benchmark_Helpers.measure("Js.Array2.sort with Ocaml compare", jsArray2withOcamlCompare)
     Benchmark_Helpers.measure("Array.fast_sort", ocamlArray)
diff --git a/packages/squiggle-lang/benchmark/Benchmark_Helpers.res b/packages/squiggle-lang/benchmark/Benchmark_Helpers.res
index 0e889d15..e6365bea 100644
--- a/packages/squiggle-lang/benchmark/Benchmark_Helpers.res
+++ b/packages/squiggle-lang/benchmark/Benchmark_Helpers.res
@@ -1,11 +1,11 @@
 module type BenchmarkTopic = {
-  let runAll: () => unit
+  let runAll: unit => unit
 }
 
-let measure = (name: string, f: () => unit) => {
-    let start = Js.Date.make()->Js.Date.valueOf
-    f()
-    let end = Js.Date.make()->Js.Date.valueOf
-    let duration = (end -. start) /. 1000.
-    Js.log2(duration, name)
+let measure = (name: string, f: unit => unit) => {
+  let start = Js.Date.make()->Js.Date.valueOf
+  f()
+  let end = Js.Date.make()->Js.Date.valueOf
+  let duration = (end -. start) /. 1000.
+  Js.log2(duration, name)
 }
diff --git a/packages/squiggle-lang/benchmark/Benchmark_Map.res b/packages/squiggle-lang/benchmark/Benchmark_Map.res
index d04d501d..ee9ae51b 100644
--- a/packages/squiggle-lang/benchmark/Benchmark_Map.res
+++ b/packages/squiggle-lang/benchmark/Benchmark_Map.res
@@ -2,63 +2,61 @@ module StringMap: Benchmark_Helpers.BenchmarkTopic = {
   let size = 1000
   let iterations = 10_000
 
-    let kv = Belt.Array.range(1, size)->Belt.Array.map(
-        v => ("key" ++ v->Belt.Int.toString, v)
-    )
+  let kv = Belt.Array.range(1, size)->Belt.Array.map(v => ("key" ++ v->Belt.Int.toString, v))
 
   let beltMap = () => {
     Belt.Range.forEach(1, iterations, _ => {
-        let m = Belt.Map.String.empty
-        let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => acc->Belt.Map.String.set(k, v))
+      let m = Belt.Map.String.empty
+      let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => acc->Belt.Map.String.set(k, v))
     })
   }
 
   let beltMutableMap = () => {
     Belt.Range.forEach(1, iterations, _ => {
-        let m = Belt.MutableMap.String.make()
-        let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => {
-            acc->Belt.MutableMap.String.set(k, v)
-            acc
-        })
+      let m = Belt.MutableMap.String.make()
+      let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => {
+        acc->Belt.MutableMap.String.set(k, v)
+        acc
+      })
     })
   }
 
   let beltHashMap = () => {
     Belt.Range.forEach(1, iterations, _ => {
-        let m = Belt.HashMap.String.make(~hintSize=100)
-        let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => {
-            acc->Belt.HashMap.String.set(k, v)
-            acc
-        })
+      let m = Belt.HashMap.String.make(~hintSize=100)
+      let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => {
+        acc->Belt.HashMap.String.set(k, v)
+        acc
+      })
     })
   }
 
   let jsDict = () => {
     Belt.Range.forEach(1, iterations, _ => {
-        let m = Js.Dict.empty()
-        let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => {
-            acc->Js.Dict.set(k, v)
-            acc
-        })
+      let m = Js.Dict.empty()
+      let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => {
+        acc->Js.Dict.set(k, v)
+        acc
+      })
     })
   }
 
   let jsMap = () => {
     Belt.Range.forEach(1, iterations, _ => {
-        let m = Js_map.make()
-        let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) =>
-            acc->Js_map.set(k, v)
-        )
+      let m = Js_map.make()
+      let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => acc->Js_map.set(k, v))
     })
   }
 
   let runAll = () => {
-      Js.log(`Filling a map with ("key{i}" => "i") key-value pairs, size ${size->Js.Int.toString} (${iterations->Js.Int.toString} iterations)`)
-      Benchmark_Helpers.measure("Belt.Map.String", beltMap)
-      Benchmark_Helpers.measure("Belt.MutableMap.String", beltMutableMap)
-      Benchmark_Helpers.measure("Belt.HashMap.String", beltHashMap)
-      Benchmark_Helpers.measure("Js.Dict", jsDict)
-      Benchmark_Helpers.measure("Js.Map", jsMap)
+    Js.log(
+      `Filling a map with ("key{i}" => "i") key-value pairs, size ${size->Js.Int.toString} (${iterations->Js.Int.toString} iterations)`,
+    )
+    Benchmark_Helpers.measure("Belt.Map.String", beltMap)
+    Benchmark_Helpers.measure("Belt.MutableMap.String", beltMutableMap)
+    Benchmark_Helpers.measure("Belt.HashMap.String", beltHashMap)
+    Benchmark_Helpers.measure("Js.Dict", jsDict)
+    Benchmark_Helpers.measure("Js.Map", jsMap)
   }
 }
 
diff --git a/packages/squiggle-lang/src/rescript/FR/FR_Builtin.res b/packages/squiggle-lang/src/rescript/FR/FR_Builtin.res
new file mode 100644
index 00000000..7ab3b1a9
--- /dev/null
+++ b/packages/squiggle-lang/src/rescript/FR/FR_Builtin.res
@@ -0,0 +1,123 @@
+open FunctionRegistry_Core
+open FunctionRegistry_Helpers
+
+let nameSpace = "" // no namespaced versions
+
+type simpleDefinition = {
+  inputs: array<frType>,
+  fn: array<internalExpressionValue> => result<internalExpressionValue, errorValue>,
+}
+
+let makeFnMany = (name: string, definitions: array<simpleDefinition>) =>
+  Function.make(
+    ~name,
+    ~nameSpace,
+    ~requiresNamespace=false,
+    ~definitions=definitions->Js.Array2.map(({inputs, fn}) =>
+      FnDefinition.make(~name, ~inputs, ~run=(inputs, _, _, _) => fn(inputs), ())
+    ),
+    (),
+  )
+
+let makeFn = (
+  name: string,
+  inputs: array<frType>,
+  fn: array<internalExpressionValue> => result<internalExpressionValue, errorValue>,
+) => makeFnMany(name, [{inputs: inputs, fn: fn}])
+
+let makeFF2F = (name: string, fn: (float, float) => float) => {
+  makeFn(name, [FRTypeNumber, FRTypeNumber], inputs => {
+    switch inputs {
+    | [IEvNumber(x), IEvNumber(y)] => fn(x, y)->IEvNumber->Ok
+    | _ => Error(impossibleError)
+    }
+  })
+}
+
+let makeFF2B = (name: string, fn: (float, float) => bool) => {
+  makeFn(name, [FRTypeNumber, FRTypeNumber], inputs => {
+    switch inputs {
+    | [IEvNumber(x), IEvNumber(y)] => fn(x, y)->IEvBool->Ok
+    | _ => Error(impossibleError)
+    }
+  })
+}
+
+let makeBB2B = (name: string, fn: (bool, bool) => bool) => {
+  makeFn(name, [FRTypeBool, FRTypeBool], inputs => {
+    switch inputs {
+    | [IEvBool(x), IEvBool(y)] => fn(x, y)->IEvBool->Ok
+    | _ => Error(impossibleError)
+    }
+  })
+}
+
+let library = [
+  makeFF2F("add", (x, y) => x +. y), // infix + (see Reducer/Reducer_Peggy/helpers.ts)
+  makeFF2F("subtract", (x, y) => x -. y), // infix -
+  makeFF2F("multiply", (x, y) => x *. y), // infix *
+  makeFF2F("divide", (x, y) => x /. y), // infix /
+  makeFF2F("pow", (x, y) => Js.Math.pow_float(~base=x, ~exp=y)), // infix ^
+  makeFF2B("equal", (x, y) => x == y), // infix ==
+  makeFF2B("smaller", (x, y) => x < y), // infix <
+  makeFF2B("smallerEq", (x, y) => x <= y), // infix <=
+  makeFF2B("larger", (x, y) => x > y), // infix >
+  makeFF2B("largerEq", (x, y) => x >= y), // infix >=
+  makeBB2B("or", (x, y) => x || y), // infix ||
+  makeBB2B("and", (x, y) => x && y), // infix &&
+  makeFn("unaryMinus", [FRTypeNumber], inputs => { // unary prefix -
+    switch inputs {
+    | [IEvNumber(x)] => IEvNumber(-.x)->Ok
+    | _ => Error(impossibleError)
+    }
+  }),
+  makeFn("not", [FRTypeNumber], inputs => { // unary prefix !
+    switch inputs {
+    | [IEvNumber(x)] => IEvBool(x != 0.)->Ok
+    | _ => Error(impossibleError)
+    }
+  }),
+  makeFn("not", [FRTypeBool], inputs => { // unary prefix !
+    switch inputs {
+    | [IEvBool(x)] => IEvBool(!x)->Ok
+    | _ => Error(impossibleError)
+    }
+  }),
+  makeFn("concat", [FRTypeString, FRTypeString], inputs => {
+    switch inputs {
+    | [IEvString(a), IEvString(b)] => {
+        let answer = Js.String2.concat(a, b)
+        answer->Reducer_T.IEvString->Ok
+      }
+    | _ => Error(impossibleError)
+    }
+  }),
+  makeFn("concat", [FRTypeArray(FRTypeAny), FRTypeArray(FRTypeAny)], inputs => {
+    switch inputs {
+    | [IEvArray(originalA), IEvArray(b)] => {
+        let a = originalA->Js.Array2.copy
+        let _ = Js.Array2.pushMany(a, b)
+        a->Reducer_T.IEvArray->Ok
+      }
+    | _ => Error(impossibleError)
+    }
+  }),
+  makeFn("inspect", [FRTypeAny], inputs => {
+    switch inputs {
+    | [value] => {
+        Js.log(value->ReducerInterface_InternalExpressionValue.toString)
+        value->Ok
+      }
+    | _ => Error(impossibleError)
+    }
+  }),
+  makeFn("inspect", [FRTypeAny, FRTypeString], inputs => {
+    switch inputs {
+    | [value, IEvString(label)] => {
+        Js.log(`${label}: ${value->ReducerInterface_InternalExpressionValue.toString}`)
+        value->Ok
+      }
+    | _ => Error(impossibleError)
+    }
+  }),
+]
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Danger.res b/packages/squiggle-lang/src/rescript/FR/FR_Danger.res
similarity index 92%
rename from packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Danger.res
rename to packages/squiggle-lang/src/rescript/FR/FR_Danger.res
index 71624f60..f457a8f7 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Danger.res
+++ b/packages/squiggle-lang/src/rescript/FR/FR_Danger.res
@@ -8,11 +8,11 @@ let requiresNamespace = true
 
 module Combinatorics = {
   module Helpers = {
-    let laplace = ((successes, trials)) => (successes +. 1.0) /. (trials +. 2.0)
+    let laplace = (successes, trials) => (successes +. 1.0) /. (trials +. 2.0)
     let factorial = Stdlib.Math.factorial
-    let choose = ((n, k)) => factorial(n) /. (factorial(n -. k) *. factorial(k))
+    let choose = (n, k) => factorial(n) /. (factorial(n -. k) *. factorial(k))
     let pow = (base, exp) => Js.Math.pow_float(~base, ~exp)
-    let binomial = ((n, k, p)) => choose((n, k)) *. pow(p, k) *. pow(1.0 -. p, n -. k)
+    let binomial = (n, k, p) => choose(n, k) *. pow(p, k) *. pow(1.0 -. p, n -. k)
   }
   module Lib = {
     let laplace = Function.make(
@@ -77,8 +77,7 @@ module Integration = {
         | Reducer_T.IEvNumber(x) => Ok(x)
         | _ =>
           Error(
-            "Error 1 in Danger.integrate. It's possible that your function doesn't return a number, try definining auxiliaryFunction(x) = mean(yourFunction(x)) and integrate auxiliaryFunction instead"
-            ->Reducer_ErrorValue.REOther
+            "Error 1 in Danger.integrate. It's possible that your function doesn't return a number, try definining auxiliaryFunction(x) = mean(yourFunction(x)) and integrate auxiliaryFunction instead"->Reducer_ErrorValue.REOther,
           )
         }
         result
@@ -142,11 +141,11 @@ module Integration = {
           resultWithOuterPoints
         }
       | Error(b) =>
-        (
-          "Integration error 2 in Danger.integrate. It's possible that your function doesn't return a number, try definining auxiliaryFunction(x) = mean(yourFunction(x)) and integrate auxiliaryFunction instead." ++
-          "Original error: " ++
-          b->Reducer_ErrorValue.errorToString
-        )->Reducer_ErrorValue.REOther->Error
+        ("Integration error 2 in Danger.integrate. It's possible that your function doesn't return a number, try definining auxiliaryFunction(x) = mean(yourFunction(x)) and integrate auxiliaryFunction instead." ++
+        "Original error: " ++
+        b->Reducer_ErrorValue.errorToString)
+        ->Reducer_ErrorValue.REOther
+        ->Error
       }
       result
     }
@@ -169,7 +168,9 @@ module Integration = {
           ~run=(inputs, _, env, reducer) => {
             let result = switch inputs {
             | [_, _, _, IEvNumber(0.0)] =>
-              "Integration error 4 in Danger.integrate: Increment can't be 0."->Reducer_ErrorValue.REOther->Error
+              "Integration error 4 in Danger.integrate: Increment can't be 0."
+              ->Reducer_ErrorValue.REOther
+              ->Error
             | [
                 IEvLambda(aLambda),
                 IEvNumber(min),
@@ -186,7 +187,9 @@ module Integration = {
               )
             | _ =>
               Error(
-                Reducer_ErrorValue.REOther("Integration error 5 in Danger.integrate. Remember that inputs are (function, number (min), number (max), number(increment))")
+                Reducer_ErrorValue.REOther(
+                  "Integration error 5 in Danger.integrate. Remember that inputs are (function, number (min), number (max), number(increment))",
+                ),
               )
             }
             result
@@ -221,8 +224,8 @@ module Integration = {
                 env,
                 reducer,
               )->E.R2.errMap(b =>
-                ("Integration error 7 in Danger.integrate. Something went wrong along the way: " ++ b->Reducer_ErrorValue.errorToString)
-                ->Reducer_ErrorValue.REOther
+                ("Integration error 7 in Danger.integrate. Something went wrong along the way: " ++
+                b->Reducer_ErrorValue.errorToString)->Reducer_ErrorValue.REOther
               )
             | _ =>
               "Integration error 8 in Danger.integrate. Remember that inputs are (function, number (min), number (max), number(increment))"
@@ -287,23 +290,19 @@ module DiminishingReturns = {
       ) {
       | (false, _, _, _) =>
         Error(
-          "Error in Danger.optimalAllocationGivenDiminishingMarginalReturnsForManyFunctions, number of functions should be greater than 1."
-          ->Reducer_ErrorValue.REOther
+          "Error in Danger.optimalAllocationGivenDiminishingMarginalReturnsForManyFunctions, number of functions should be greater than 1."->Reducer_ErrorValue.REOther,
         )
       | (_, false, _, _) =>
         Error(
-          "Error in Danger.optimalAllocationGivenDiminishingMarginalReturnsForManyFunctions, funds should be greater than 0."
-          ->Reducer_ErrorValue.REOther
+          "Error in Danger.optimalAllocationGivenDiminishingMarginalReturnsForManyFunctions, funds should be greater than 0."->Reducer_ErrorValue.REOther,
         )
       | (_, _, false, _) =>
         Error(
-          "Error in Danger.optimalAllocationGivenDiminishingMarginalReturnsForManyFunctions, approximateIncrement should be greater than 0."
-          ->Reducer_ErrorValue.REOther
+          "Error in Danger.optimalAllocationGivenDiminishingMarginalReturnsForManyFunctions, approximateIncrement should be greater than 0."->Reducer_ErrorValue.REOther,
         )
       | (_, _, _, false) =>
         Error(
-          "Error in Danger.optimalAllocationGivenDiminishingMarginalReturnsForManyFunctions, approximateIncrement should be smaller than funds amount."
-          ->Reducer_ErrorValue.REOther
+          "Error in Danger.optimalAllocationGivenDiminishingMarginalReturnsForManyFunctions, approximateIncrement should be smaller than funds amount."->Reducer_ErrorValue.REOther,
         )
       | (true, true, true, true) => {
           let applyFunctionAtPoint = (lambda, point: float) => {
@@ -319,8 +318,7 @@ module DiminishingReturns = {
             | Reducer_T.IEvNumber(x) => Ok(x)
             | _ =>
               Error(
-                "Error 1 in Danger.optimalAllocationGivenDiminishingMarginalReturnsForManyFunctions. It's possible that your function doesn't return a number, try definining auxiliaryFunction(x) = mean(yourFunction(x)) and integrate auxiliaryFunction instead"
-                ->Reducer_ErrorValue.REOther
+                "Error 1 in Danger.optimalAllocationGivenDiminishingMarginalReturnsForManyFunctions. It's possible that your function doesn't return a number, try definining auxiliaryFunction(x) = mean(yourFunction(x)) and integrate auxiliaryFunction instead"->Reducer_ErrorValue.REOther,
               )
             }
           }
@@ -433,7 +431,10 @@ module DiminishingReturns = {
                 }
                 result
               }
-            | _ => "Error in Danger.diminishingMarginalReturnsForTwoFunctions"->Reducer_ErrorValue.REOther->Error
+            | _ =>
+              "Error in Danger.diminishingMarginalReturnsForTwoFunctions"
+              ->Reducer_ErrorValue.REOther
+              ->Error
             },
           (),
         ),
diff --git a/packages/squiggle-lang/src/rescript/FR/FR_Date.res b/packages/squiggle-lang/src/rescript/FR/FR_Date.res
new file mode 100644
index 00000000..96f94b9d
--- /dev/null
+++ b/packages/squiggle-lang/src/rescript/FR/FR_Date.res
@@ -0,0 +1,159 @@
+open FunctionRegistry_Core
+open FunctionRegistry_Helpers
+
+let makeFn = (
+  name: string,
+  inputs: array<frType>,
+  fn: array<internalExpressionValue> => result<internalExpressionValue, errorValue>,
+) =>
+  Function.make(
+    ~name,
+    ~nameSpace="",
+    ~requiresNamespace=false,
+    ~definitions=[FnDefinition.make(~name, ~inputs, ~run=(inputs, _, _, _) => fn(inputs), ())],
+    (),
+  )
+
+let makeNumberToDurationFn = (name: string, fn: float => DateTime.Duration.t) =>
+  Function.make(
+    ~name,
+    ~nameSpace="",
+    ~requiresNamespace=false,
+    ~definitions=[
+      FnDefinition.make(
+        ~name,
+        ~inputs=[FRTypeNumber],
+        ~run=(inputs, _, _, _) =>
+          switch inputs {
+          | [IEvNumber(t)] => IEvTimeDuration(fn(t))->Ok
+          | _ => Error(impossibleError)
+          },
+        (),
+      ),
+    ],
+    (),
+  )
+
+let makeDurationToNumberFn = (name: string, fn: DateTime.Duration.t => float) =>
+  Function.make(
+    ~name,
+    ~nameSpace="",
+    ~requiresNamespace=false,
+    ~definitions=[
+      FnDefinition.make(
+        ~name,
+        ~inputs=[FRTypeTimeDuration],
+        ~run=(inputs, _, _, _) =>
+          switch inputs {
+          | [IEvTimeDuration(t)] => IEvNumber(fn(t))->Ok
+          | _ => Error(impossibleError)
+          },
+        (),
+      ),
+    ],
+    (),
+  )
+
+let library = [
+  makeFn("toString", [FRTypeDate], inputs =>
+    switch inputs {
+    | [IEvDate(t)] => IEvString(DateTime.Date.toString(t))->Ok
+    | _ => Error(impossibleError)
+    }
+  ),
+  makeFn("makeDateFromYear", [FRTypeNumber], inputs =>
+    switch inputs {
+    | [IEvNumber(year)] =>
+      switch DateTime.Date.makeFromYear(year) {
+      | Ok(t) => IEvDate(t)->Ok
+      | Error(e) => Reducer_ErrorValue.RETodo(e)->Error
+      }
+    | _ => Error(impossibleError)
+    }
+  ),
+  makeFn("dateFromNumber", [FRTypeNumber], inputs =>
+    switch inputs {
+    | [IEvNumber(f)] => IEvDate(DateTime.Date.fromFloat(f))->Ok
+    | _ => Error(impossibleError)
+    }
+  ),
+  makeFn("toNumber", [FRTypeDate], inputs =>
+    switch inputs {
+    | [IEvDate(f)] => IEvNumber(DateTime.Date.toFloat(f))->Ok
+    | _ => Error(impossibleError)
+    }
+  ),
+  makeFn("subtract", [FRTypeDate, FRTypeDate], inputs =>
+    switch inputs {
+    | [IEvDate(d1), IEvDate(d2)] =>
+      switch DateTime.Date.subtract(d1, d2) {
+      | Ok(d) => IEvTimeDuration(d)->Ok
+      | Error(e) => Error(RETodo(e))
+      }
+    | _ => Error(impossibleError)
+    }
+  ),
+  makeFn("subtract", [FRTypeDate, FRTypeTimeDuration], inputs =>
+    switch inputs {
+    | [IEvDate(d1), IEvTimeDuration(d2)] => IEvDate(DateTime.Date.subtractDuration(d1, d2))->Ok
+    | _ => Error(impossibleError)
+    }
+  ),
+  makeFn("add", [FRTypeDate, FRTypeTimeDuration], inputs =>
+    switch inputs {
+    | [IEvDate(d1), IEvTimeDuration(d2)] => IEvDate(DateTime.Date.addDuration(d1, d2))->Ok
+    | _ => Error(impossibleError)
+    }
+  ),
+  makeFn("toString", [FRTypeTimeDuration], inputs =>
+    switch inputs {
+    | [IEvTimeDuration(t)] => IEvString(DateTime.Duration.toString(t))->Ok
+    | _ => Error(impossibleError)
+    }
+  ),
+  makeNumberToDurationFn("minutes", DateTime.Duration.fromMinutes),
+  makeNumberToDurationFn("fromUnit_minutes", DateTime.Duration.fromMinutes),
+  makeNumberToDurationFn("hours", DateTime.Duration.fromHours),
+  makeNumberToDurationFn("fromUnit_hours", DateTime.Duration.fromHours),
+  makeNumberToDurationFn("days", DateTime.Duration.fromDays),
+  makeNumberToDurationFn("fromUnit_days", DateTime.Duration.fromDays),
+  makeNumberToDurationFn("years", DateTime.Duration.fromYears),
+  makeNumberToDurationFn("fromUnit_years", DateTime.Duration.fromYears),
+  makeDurationToNumberFn("toMinutes", DateTime.Duration.toMinutes),
+  makeDurationToNumberFn("toHours", DateTime.Duration.toHours),
+  makeDurationToNumberFn("toDays", DateTime.Duration.toDays),
+  makeDurationToNumberFn("toYears", DateTime.Duration.toYears),
+  makeFn("add", [FRTypeTimeDuration, FRTypeTimeDuration], inputs =>
+    switch inputs {
+    | [IEvTimeDuration(d1), IEvTimeDuration(d2)] =>
+      IEvTimeDuration(DateTime.Duration.add(d1, d2))->Ok
+    | _ => Error(impossibleError)
+    }
+  ),
+  makeFn("subtract", [FRTypeTimeDuration, FRTypeTimeDuration], inputs =>
+    switch inputs {
+    | [IEvTimeDuration(d1), IEvTimeDuration(d2)] =>
+      IEvTimeDuration(DateTime.Duration.subtract(d1, d2))->Ok
+    | _ => Error(impossibleError)
+    }
+  ),
+  makeFn("multiply", [FRTypeTimeDuration, FRTypeNumber], inputs =>
+    switch inputs {
+    | [IEvTimeDuration(d1), IEvNumber(d2)] =>
+      IEvTimeDuration(DateTime.Duration.multiply(d1, d2))->Ok
+    | _ => Error(impossibleError)
+    }
+  ),
+  makeFn("divide", [FRTypeTimeDuration, FRTypeNumber], inputs =>
+    switch inputs {
+    | [IEvTimeDuration(d1), IEvNumber(d2)] => IEvTimeDuration(DateTime.Duration.divide(d1, d2))->Ok
+    | _ => Error(impossibleError)
+    }
+  ),
+  makeFn("divide", [FRTypeTimeDuration, FRTypeTimeDuration], inputs =>
+    switch inputs {
+    | [IEvTimeDuration(d1), IEvTimeDuration(d2)] => IEvNumber(d1 /. d2)->Ok
+    | _ => Error(impossibleError)
+    }
+  ),
+]
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Dict.res b/packages/squiggle-lang/src/rescript/FR/FR_Dict.res
similarity index 98%
rename from packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Dict.res
rename to packages/squiggle-lang/src/rescript/FR/FR_Dict.res
index f1cd86f3..310d295d 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Dict.res
+++ b/packages/squiggle-lang/src/rescript/FR/FR_Dict.res
@@ -17,7 +17,10 @@ module Internals = {
     ->E.A2.fmap(((key, value)) => Wrappers.evArray([IEvString(key), value]))
     ->Wrappers.evArray
 
-  let fromList = (items: array<internalExpressionValue>): result<internalExpressionValue, errorValue> =>
+  let fromList = (items: array<internalExpressionValue>): result<
+    internalExpressionValue,
+    errorValue,
+  > =>
     items
     ->E.A2.fmap(item => {
       switch (item: internalExpressionValue) {
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Dist.res b/packages/squiggle-lang/src/rescript/FR/FR_Dist.res
similarity index 100%
rename from packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Dist.res
rename to packages/squiggle-lang/src/rescript/FR/FR_Dist.res
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Fn.res b/packages/squiggle-lang/src/rescript/FR/FR_Fn.res
similarity index 100%
rename from packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Fn.res
rename to packages/squiggle-lang/src/rescript/FR/FR_Fn.res
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_GenericDist.res b/packages/squiggle-lang/src/rescript/FR/FR_GenericDist.res
similarity index 94%
rename from packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_GenericDist.res
rename to packages/squiggle-lang/src/rescript/FR/FR_GenericDist.res
index 5b7d5dca..dc449ee4 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_GenericDist.res
+++ b/packages/squiggle-lang/src/rescript/FR/FR_GenericDist.res
@@ -315,10 +315,11 @@ module Old = {
 
   let dispatch = (call: ReducerInterface_InternalExpressionValue.functionCall, environment) =>
     switch dispatchToGenericOutput(call, environment) {
-        | Some(o) => genericOutputToReducerValue(o)
-        | None => Reducer_ErrorValue.REOther("Internal error in FR_GenericDist implementation")
-          ->Reducer_ErrorValue.ErrorException
-          ->raise
+    | Some(o) => genericOutputToReducerValue(o)
+    | None =>
+      Reducer_ErrorValue.REOther("Internal error in FR_GenericDist implementation")
+      ->Reducer_ErrorValue.ErrorException
+      ->raise
     }
 }
 
@@ -340,24 +341,32 @@ let makeProxyFn = (name: string, inputs: array<frType>) => {
 }
 
 let makeOperationFns = (): array<function> => {
-    let ops = ["add", "multiply", "subtract", "divide", "pow", "log", "dotAdd", "dotMultiply", "dotSubtract", "dotDivide", "dotPow"]
-    let twoArgTypes = [
-        // can't use numeric+numeric, since number+number should be delegated to builtin arithmetics
-        [FRTypeDist, FRTypeNumber],
-        [FRTypeNumber, FRTypeDist],
-        [FRTypeDist, FRTypeDist],
-    ]
+  let ops = [
+    "add",
+    "multiply",
+    "subtract",
+    "divide",
+    "pow",
+    "log",
+    "dotAdd",
+    "dotMultiply",
+    "dotSubtract",
+    "dotDivide",
+    "dotPow",
+  ]
+  let twoArgTypes = [
+    // can't use numeric+numeric, since number+number should be delegated to builtin arithmetics
+    [FRTypeDist, FRTypeNumber],
+    [FRTypeNumber, FRTypeDist],
+    [FRTypeDist, FRTypeDist],
+  ]
 
-    ops->E.A2.fmap(
-        op => twoArgTypes->E.A2.fmap(
-            types => makeProxyFn(op, types)
-        )
-    )->E.A.concatMany
+  ops->E.A2.fmap(op => twoArgTypes->E.A2.fmap(types => makeProxyFn(op, types)))->E.A.concatMany
 }
 
 // TODO - duplicates the switch above, should rewrite with standard FR APIs
 let library = E.A.concatMany([
-    [
+  [
     makeProxyFn("triangular", [FRTypeNumber, FRTypeNumber, FRTypeNumber]),
     makeProxyFn("sample", [FRTypeDist]),
     makeProxyFn("sampleN", [FRTypeDist, FRTypeNumber]),
@@ -394,14 +403,14 @@ let library = E.A.concatMany([
     makeProxyFn("log10", [FRTypeDist]),
     makeProxyFn("unaryMinus", [FRTypeDist]),
     makeProxyFn("dotExp", [FRTypeDist]),
-    ],
-    makeOperationFns()
+  ],
+  makeOperationFns(),
 ])
 
 // FIXME - impossible to implement with FR due to arbitrary parameters length;
 let mxLambda = Reducer_Expression_Lambda.makeFFILambda((inputs, env, _) => {
-    switch Old.dispatch(("mx", inputs), env) {
-    | Ok(value) => value
-    | Error(e) => e->Reducer_ErrorValue.ErrorException->raise
-    }
+  switch Old.dispatch(("mx", inputs), env) {
+  | Ok(value) => value
+  | Error(e) => e->Reducer_ErrorValue.ErrorException->raise
+  }
 })
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_List.res b/packages/squiggle-lang/src/rescript/FR/FR_List.res
similarity index 98%
rename from packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_List.res
rename to packages/squiggle-lang/src/rescript/FR/FR_List.res
index da9228ca..eb6a653a 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_List.res
+++ b/packages/squiggle-lang/src/rescript/FR/FR_List.res
@@ -66,12 +66,7 @@ module Internals = {
     reducer: Reducer_T.reducerFn,
   ) => {
     Js.Array2.filter(aValueArray, elem => {
-      let result = Reducer_Expression_Lambda.doLambdaCall(
-        aLambdaValue,
-        [elem],
-        env,
-        reducer,
-      )
+      let result = Reducer_Expression_Lambda.doLambdaCall(aLambdaValue, [elem], env, reducer)
       switch result {
       | IEvBool(true) => true
       | _ => false
diff --git a/packages/squiggle-lang/src/rescript/FR/FR_Mathjs.res b/packages/squiggle-lang/src/rescript/FR/FR_Mathjs.res
new file mode 100644
index 00000000..9bffde42
--- /dev/null
+++ b/packages/squiggle-lang/src/rescript/FR/FR_Mathjs.res
@@ -0,0 +1,70 @@
+open FunctionRegistry_Core
+open FunctionRegistry_Helpers
+
+// FIXME - copy-pasted (see FR_Date.res and others)
+let makeFn = (
+  name: string,
+  inputs: array<frType>,
+  fn: array<internalExpressionValue> => result<internalExpressionValue, errorValue>,
+) =>
+  Function.make(
+    ~name,
+    ~nameSpace="",
+    ~requiresNamespace=false,
+    ~definitions=[FnDefinition.make(~name, ~inputs, ~run=(inputs, _, _, _) => fn(inputs), ())],
+    (),
+  )
+
+@module("mathjs") external dummy_: string => unit = "evaluate"
+let dummy1_ = dummy_ //Deceive the compiler to make the import although we wont make a call from rescript. Otherwise the optimizer deletes the import
+
+let mathjsCall1: (string, float) => 'a = %raw(`function (name, arg) { return Mathjs[name](arg); }`)
+let mathjsCall2: (string, float, float) => 'a = %raw(`function (name, arg1, arg2) { return Mathjs[name](arg1, arg2); }`)
+
+let makeMathjsFn1 = (
+  name: string
+) => {
+  makeFn(name, [FRTypeNumber], inputs => {
+    switch inputs {
+    | [IEvNumber(x)] => mathjsCall1(name, x)->Reducer_Js_Gate.jsToIEv
+    | _ => Error(impossibleError)
+    }
+  })
+}
+
+let makeMathjsFn2 = (
+  name: string
+) => {
+  makeFn(name, [FRTypeNumber, FRTypeNumber], inputs => {
+    switch inputs {
+    | [IEvNumber(x), IEvNumber(y)] => mathjsCall2(name, x, y)->Reducer_Js_Gate.jsToIEv
+    | _ => Error(impossibleError)
+    }
+  })
+}
+
+let library = [
+  // TODO - other MathJS
+  // https://mathjs.org/docs/reference/functions.html
+
+  // Arithmetic functions
+  makeMathjsFn1("abs"),
+  makeMathjsFn1("cbrt"),
+  makeMathjsFn1("ceil"),
+  makeMathjsFn1("cube"),
+  makeMathjsFn1("exp"),
+  makeMathjsFn1("fix"),
+  makeMathjsFn1("floor"),
+
+  makeMathjsFn2("gcd"),
+  makeMathjsFn2("hypot"),
+  makeMathjsFn2("invmod"),
+  makeMathjsFn2("lcm"),
+  makeMathjsFn1("log"), // Do we need makeMathjsFn2 for `log` too?
+  makeMathjsFn1("log10"),
+  makeMathjsFn1("log2"),
+
+  makeMathjsFn1("factorial"),
+  makeMathjsFn1("cos"),
+
+]
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Number.res b/packages/squiggle-lang/src/rescript/FR/FR_Number.res
similarity index 94%
rename from packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Number.res
rename to packages/squiggle-lang/src/rescript/FR/FR_Number.res
index 90707891..bd05164c 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Number.res
+++ b/packages/squiggle-lang/src/rescript/FR/FR_Number.res
@@ -17,18 +17,6 @@ module ArrayNumberDist = {
       (),
     )
   }
-  let make2 = (name, fn) => {
-    FnDefinition.make(
-      ~name,
-      ~inputs=[FRTypeArray(FRTypeAny)],
-      ~run=(_, inputs, _, _) =>
-        Prepare.ToTypedArray.numbers(inputs)
-        ->E.R.bind(r => E.A.length(r) === 0 ? Error("List is empty") : Ok(r))
-        ->E.R.bind(fn)
-        ->E.R2.errMap(wrapError),
-      (),
-    )
-  }
 }
 
 let library = [
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Pointset.res b/packages/squiggle-lang/src/rescript/FR/FR_Pointset.res
similarity index 96%
rename from packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Pointset.res
rename to packages/squiggle-lang/src/rescript/FR/FR_Pointset.res
index 324843d7..61d03c9d 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Pointset.res
+++ b/packages/squiggle-lang/src/rescript/FR/FR_Pointset.res
@@ -111,8 +111,7 @@ let library = [
         ~name="makeContinuous",
         ~inputs=[FRTypeArray(FRTypeRecord([("x", FRTypeNumeric), ("y", FRTypeNumeric)]))],
         ~run=(_, inputs, _, _) =>
-          inputsTodist(inputs, r => Continuous(Continuous.make(r)))
-          ->E.R2.errMap(wrapError),
+          inputsTodist(inputs, r => Continuous(Continuous.make(r)))->E.R2.errMap(wrapError),
         (),
       ),
     ],
@@ -136,8 +135,7 @@ let library = [
         ~name="makeDiscrete",
         ~inputs=[FRTypeArray(FRTypeRecord([("x", FRTypeNumeric), ("y", FRTypeNumeric)]))],
         ~run=(_, inputs, _, _) =>
-          inputsTodist(inputs, r => Discrete(Discrete.make(r)))
-          ->E.R2.errMap(wrapError),
+          inputsTodist(inputs, r => Discrete(Discrete.make(r)))->E.R2.errMap(wrapError),
         (),
       ),
     ],
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Sampleset.res b/packages/squiggle-lang/src/rescript/FR/FR_Sampleset.res
similarity index 98%
rename from packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Sampleset.res
rename to packages/squiggle-lang/src/rescript/FR/FR_Sampleset.res
index b27b423e..4c04489b 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Sampleset.res
+++ b/packages/squiggle-lang/src/rescript/FR/FR_Sampleset.res
@@ -120,7 +120,8 @@ let libaryBase = [
             Prepare.ToTypedArray.numbers(inputs) |> E.R2.bind(r =>
               SampleSetDist.make(r)->E.R2.errMap(_ => "AM I HERE? WHYERE AMI??")
             )
-          sampleSet->E.R2.fmap(Wrappers.sampleSet)
+          sampleSet
+          ->E.R2.fmap(Wrappers.sampleSet)
           ->E.R2.fmap(Wrappers.evDistribution)
           ->E.R2.errMap(wrapError)
         },
@@ -291,7 +292,9 @@ module Comparison = {
   let wrapper = r =>
     r
     ->E.R2.fmap(r => r->Wrappers.sampleSet->Wrappers.evDistribution)
-    ->E.R2.errMap(e => e->DistributionTypes.Error.sampleErrorToDistErr->Reducer_ErrorValue.REDistributionError)
+    ->E.R2.errMap(e =>
+      e->DistributionTypes.Error.sampleErrorToDistErr->Reducer_ErrorValue.REDistributionError
+    )
 
   let mkBig = (name, withDist, withFloat) =>
     Function.make(
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Scoring.res b/packages/squiggle-lang/src/rescript/FR/FR_Scoring.res
similarity index 100%
rename from packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Scoring.res
rename to packages/squiggle-lang/src/rescript/FR/FR_Scoring.res
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Units.res b/packages/squiggle-lang/src/rescript/FR/FR_Units.res
similarity index 72%
rename from packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Units.res
rename to packages/squiggle-lang/src/rescript/FR/FR_Units.res
index 90ea56bc..3935b197 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Units.res
+++ b/packages/squiggle-lang/src/rescript/FR/FR_Units.res
@@ -22,14 +22,13 @@ let makeUnitFn = (name: string, multiplier: float) => {
   )
 }
 
-
 let library = [
-    makeUnitFn("n", 1E-9),
-    makeUnitFn("m", 1E-3),
-    makeUnitFn("k", 1E3),
-    makeUnitFn("M", 1E6),
-    makeUnitFn("B", 1E9),
-    makeUnitFn("G", 1E9),
-    makeUnitFn("T", 1E12),
-    makeUnitFn("P", 1E15),
+  makeUnitFn("n", 1E-9),
+  makeUnitFn("m", 1E-3),
+  makeUnitFn("k", 1E3),
+  makeUnitFn("M", 1E6),
+  makeUnitFn("B", 1E9),
+  makeUnitFn("G", 1E9),
+  makeUnitFn("T", 1E12),
+  makeUnitFn("P", 1E15),
 ]
diff --git a/packages/squiggle-lang/src/rescript/ForTS/ForTS_ReducerProject.res b/packages/squiggle-lang/src/rescript/ForTS/ForTS_ReducerProject.res
index dabd72a5..ac9c167c 100644
--- a/packages/squiggle-lang/src/rescript/ForTS/ForTS_ReducerProject.res
+++ b/packages/squiggle-lang/src/rescript/ForTS/ForTS_ReducerProject.res
@@ -212,8 +212,7 @@ let setEnvironment = (project: reducerProject, environment: environment): unit =
   project->Private.setEnvironment(environment)
 
 @genType
-let getEnvironment = (project: reducerProject): environment =>
-  project->Private.getEnvironment
+let getEnvironment = (project: reducerProject): environment => project->Private.getEnvironment
 
 /*
 Foreign function interface is intentionally demolished.
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res
index 714456a8..a5685f2e 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res
@@ -225,9 +225,9 @@ module FnDefinition = {
   }
 
   let make = (~name, ~inputs, ~run, ()): t => {
-    name,
-    inputs,
-    run,
+    name: name,
+    inputs: inputs,
+    run: run,
   }
 }
 
@@ -253,14 +253,14 @@ module Function = {
     ~isExperimental=false,
     (),
   ): t => {
-    name,
-    nameSpace,
-    definitions,
-    output,
+    name: name,
+    nameSpace: nameSpace,
+    definitions: definitions,
+    output: output,
     examples: examples |> E.O.default([]),
-    isExperimental,
-    requiresNamespace,
-    description,
+    isExperimental: isExperimental,
+    requiresNamespace: requiresNamespace,
+    description: description,
   }
 
   let toJson = (t: t): functionJson => {
@@ -288,12 +288,8 @@ module Registry = {
     // 1. functions
     // 2. definitions of each function
     // 3. name variations of each definition
-    r->Belt.Array.reduce(
-      Belt.Map.String.empty,
-      (acc, fn) =>
-      fn.definitions->Belt.Array.reduce(
-        acc,
-        (acc, def) => {
+    r->Belt.Array.reduce(Belt.Map.String.empty, (acc, fn) =>
+      fn.definitions->Belt.Array.reduce(acc, (acc, def) => {
         let names =
           [
             fn.nameSpace == "" ? [] : [`${fn.nameSpace}.${def.name}`],
@@ -338,8 +334,7 @@ module Registry = {
 
         let match = definitions->Js.Array2.find(def => def->FnDefinition.isMatch(args))
         switch match {
-        | Some(def) =>
-          def->FnDefinition.run(args, env, reducer)
+        | Some(def) => def->FnDefinition.run(args, env, reducer)
         | None => REOther(showNameMatchDefinitions())->Error
         }
       }
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Helpers.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Helpers.res
index 6a3931af..cf24bfc4 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Helpers.res
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Helpers.res
@@ -225,13 +225,11 @@ module DefineFn = {
       FnDefinition.make(
         ~name,
         ~inputs=[FRTypeNumber],
-        ~run=(_, inputs, _, _) => {
-          inputs
-          ->getOrError(0)
-          ->E.R.bind(Prepare.oneNumber)
-          ->E.R2.fmap(fn)
-          ->E.R2.fmap(Wrappers.evNumber)
-          ->E.R2.errMap(e => Reducer_ErrorValue.REOther(e))
+        ~run=(inputs, _, _, _) => {
+          switch inputs {
+          | [IEvNumber(x)] => fn(x)->IEvNumber->Ok
+          | _ => Error(impossibleError)
+          }
         },
         (),
       )
@@ -239,12 +237,11 @@ module DefineFn = {
       FnDefinition.make(
         ~name,
         ~inputs=[FRTypeNumber, FRTypeNumber],
-        ~run=(_, inputs, _, _) => {
-          inputs
-          ->Prepare.ToValueTuple.twoNumbers
-          ->E.R2.fmap(fn)
-          ->E.R2.fmap(Wrappers.evNumber)
-          ->E.R2.errMap(e => Reducer_ErrorValue.REOther(e))
+        ~run=(inputs, _, _, _) => {
+          switch inputs {
+          | [IEvNumber(x), IEvNumber(y)] => fn(x, y)->IEvNumber->Ok
+          | _ => Error(impossibleError)
+          }
         },
         (),
       )
@@ -252,12 +249,11 @@ module DefineFn = {
       FnDefinition.make(
         ~name,
         ~inputs=[FRTypeNumber, FRTypeNumber, FRTypeNumber],
-        ~run=(_, inputs, _, _) => {
-          inputs
-          ->Prepare.ToValueTuple.threeNumbers
-          ->E.R2.fmap(fn)
-          ->E.R2.fmap(Wrappers.evNumber)
-          ->E.R2.errMap(e => Reducer_ErrorValue.REOther(e))
+        ~run=(inputs, _, _, _) => {
+          switch inputs {
+          | [IEvNumber(x), IEvNumber(y), IEvNumber(z)] => fn(x, y, z)->IEvNumber->Ok
+          | _ => Error(impossibleError)
+          }
         },
         (),
       )
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Builtin.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Builtin.res
deleted file mode 100644
index b3103add..00000000
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Builtin.res
+++ /dev/null
@@ -1,163 +0,0 @@
-open FunctionRegistry_Core
-open FunctionRegistry_Helpers
-
-let nameSpace = "" // no namespaced versions
-
-type simpleDefinition = {
-  inputs: array<frType>,
-  fn: array<internalExpressionValue> => result<internalExpressionValue, errorValue>,
-}
-
-let makeFnMany = (name: string, definitions: array<simpleDefinition>) =>
-  Function.make(
-    ~name,
-    ~nameSpace,
-    ~requiresNamespace=false,
-    ~definitions=definitions->Js.Array2.map(({inputs, fn}) =>
-      FnDefinition.make(~name, ~inputs, ~run=(inputs, _, _, _) => fn(inputs), ())
-    ),
-    (),
-  )
-
-let makeFn = (
-  name: string,
-  inputs: array<frType>,
-  fn: array<internalExpressionValue> => result<internalExpressionValue, errorValue>,
-) => makeFnMany(name, [{ inputs, fn }])
-
-let makeBinaryFn = (name: string, fn: (float, float) => float) => {
-  makeFn(
-    name,
-    [FRTypeNumber, FRTypeNumber],
-    inputs => {
-      switch inputs {
-      | [IEvNumber(x), IEvNumber(y)] => fn(x, y)->IEvNumber->Ok
-      | _ => Error(impossibleError)
-      }
-    }
-  )
-}
-
-let makeBinaryCmpFn = (name: string, fn: (float, float) => bool) => {
-  makeFn(
-    name,
-    [FRTypeNumber, FRTypeNumber],
-    inputs => {
-      switch inputs {
-      | [IEvNumber(x), IEvNumber(y)] => fn(x, y)->IEvBool->Ok
-      | _ => Error(impossibleError)
-      }
-    }
-  )
-}
-
-let makeBinaryBooleanFn = (name: string, fn: (bool, bool) => bool) => {
-  makeFn(
-    name,
-    [FRTypeBool, FRTypeBool],
-    inputs => {
-      switch inputs {
-      | [IEvBool(x), IEvBool(y)] => fn(x, y)->IEvBool->Ok
-      | _ => Error(impossibleError)
-      }
-    }
-  )
-}
-
-let library = [
-  makeBinaryFn("add", (x, y) => x +. y),
-  makeBinaryFn("subtract", (x, y) => x -. y),
-  makeBinaryFn("multiply", (x, y) => x *. y),
-  makeBinaryFn("divide", (x, y) => x /. y),
-  makeBinaryFn("pow", (x, y) => Js.Math.pow_float(~base=x, ~exp=y)),
-  makeBinaryCmpFn("equal", (x, y) => x == y),
-  makeBinaryCmpFn("smaller", (x, y) => x < y),
-  makeBinaryCmpFn("smallerEq", (x, y) => x <= y),
-  makeBinaryCmpFn("larger", (x, y) => x > y),
-  makeBinaryCmpFn("largerEq", (x, y) => x >= y),
-  makeBinaryBooleanFn("or", (x, y) => x || y),
-  makeBinaryBooleanFn("and", (x, y) => x && y),
-  makeFn(
-    "unaryMinus",
-    [FRTypeNumber],
-    inputs => {
-      switch inputs {
-      | [IEvNumber(x)] => IEvNumber(-.x)->Ok
-      | _ => Error(impossibleError)
-      }
-    }
-  ),
-  makeFn(
-    "not",
-    [FRTypeNumber],
-    inputs => {
-      switch inputs {
-      | [IEvNumber(x)] => IEvBool(x != 0.)->Ok
-      | _ => Error(impossibleError)
-      }
-    }
-  ),
-  makeFn(
-    "not",
-    [FRTypeBool],
-    inputs => {
-      switch inputs {
-      | [IEvBool(x)] => IEvBool(!x)->Ok
-      | _ => Error(impossibleError)
-      }
-    }
-  ),
-  makeFn(
-    "concat",
-    [FRTypeString, FRTypeString],
-    inputs => {
-      switch inputs {
-      | [IEvString(a), IEvString(b)] => {
-        let answer = Js.String2.concat(a, b)
-        answer->Reducer_T.IEvString->Ok
-      }
-      | _ => Error(impossibleError)
-      }
-    }
-  ),
-  makeFn(
-    "concat",
-    [FRTypeArray(FRTypeAny), FRTypeArray(FRTypeAny)],
-    inputs => {
-      switch inputs {
-      | [IEvArray(originalA), IEvArray(b)] => {
-        let a = originalA->Js.Array2.copy
-        let _ = Js.Array2.pushMany(a, b)
-        a->Reducer_T.IEvArray->Ok
-      }
-      | _ => Error(impossibleError)
-      }
-    }
-  ),
-  makeFn(
-    "inspect",
-    [FRTypeAny],
-    inputs => {
-      switch inputs {
-      | [value] => {
-        Js.log(value->ReducerInterface_InternalExpressionValue.toString)
-        value->Ok
-      }
-      | _ => Error(impossibleError)
-      }
-    }
-  ),
-  makeFn(
-    "inspect",
-    [FRTypeAny, FRTypeString],
-    inputs => {
-      switch inputs {
-      | [value, IEvString(label)] => {
-        Js.log(`${label}: ${value->ReducerInterface_InternalExpressionValue.toString}`)
-        value->Ok
-      }
-      | _ => Error(impossibleError)
-      }
-    }
-  ),
-]
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Date.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Date.res
deleted file mode 100644
index 0e79d8cd..00000000
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Date.res
+++ /dev/null
@@ -1,155 +0,0 @@
-open FunctionRegistry_Core
-open FunctionRegistry_Helpers
-
-let makeFn = (
-  name: string,
-  inputs: array<frType>,
-  fn: array<internalExpressionValue> => result<internalExpressionValue, errorValue>
-) =>
-  Function.make(
-    ~name,
-    ~nameSpace="",
-    ~requiresNamespace=false,
-    ~definitions=[
-      FnDefinition.make(~name, ~inputs, ~run=(inputs, _, _, _) => fn(inputs), ())
-    ],
-    ()
-  )
-
-let makeNumberToDurationFn = (
-  name: string,
-  fn: float => DateTime.Duration.t,
-) =>
-  Function.make(
-    ~name,
-    ~nameSpace="",
-    ~requiresNamespace=false,
-    ~definitions=[
-      FnDefinition.make(~name, ~inputs=[FRTypeNumber], ~run=(inputs, _, _, _) =>
-      switch inputs {
-        | [IEvNumber(t)] => IEvTimeDuration(fn(t))->Ok
-        | _ => Error(impossibleError)
-      }, ())
-    ],
-    ()
-  )
-
-let makeDurationToNumberFn = (
-  name: string,
-  fn: DateTime.Duration.t => float,
-) =>
-  Function.make(
-    ~name,
-    ~nameSpace="",
-    ~requiresNamespace=false,
-    ~definitions=[
-      FnDefinition.make(~name, ~inputs=[FRTypeTimeDuration], ~run=(inputs, _, _, _) =>
-      switch inputs {
-        | [IEvTimeDuration(t)] => IEvNumber(fn(t))->Ok
-        | _ => Error(impossibleError)
-      }, ())
-    ],
-    ()
-  )
-
-let library = [
-    makeFn("toString", [FRTypeDate], (inputs) =>
-      switch inputs {
-        | [IEvDate(t)] => IEvString(DateTime.Date.toString(t))->Ok
-        | _ => Error(impossibleError)
-      }
-    ),
-    makeFn("makeDateFromYear", [FRTypeNumber], (inputs) =>
-      switch inputs {
-        | [IEvNumber(year)] =>
-            switch DateTime.Date.makeFromYear(year) {
-            | Ok(t) => IEvDate(t)->Ok
-            | Error(e) => Reducer_ErrorValue.RETodo(e)->Error
-            }
-        | _ => Error(impossibleError)
-      }
-    ),
-    makeFn("dateFromNumber", [FRTypeNumber], (inputs) =>
-      switch inputs {
-        | [IEvNumber(f)] => IEvDate(DateTime.Date.fromFloat(f))->Ok
-        | _ => Error(impossibleError)
-      }
-    ),
-    makeFn("toNumber", [FRTypeDate], (inputs) =>
-      switch inputs {
-        | [IEvDate(f)] => IEvNumber(DateTime.Date.toFloat(f))->Ok
-        | _ => Error(impossibleError)
-      }
-    ),
-    makeFn("subtract", [FRTypeDate, FRTypeDate], (inputs) =>
-      switch inputs {
-        | [IEvDate(d1), IEvDate(d2)] => switch DateTime.Date.subtract(d1, d2) {
-            | Ok(d) => IEvTimeDuration(d)->Ok
-            | Error(e) => Error(RETodo(e))
-            }
-        | _ => Error(impossibleError)
-      }
-    ),
-    makeFn("subtract", [FRTypeDate, FRTypeTimeDuration], (inputs) =>
-      switch inputs {
-        | [IEvDate(d1), IEvTimeDuration(d2)] => 
-            IEvDate(DateTime.Date.subtractDuration(d1, d2))->Ok
-        | _ => Error(impossibleError)
-      }
-    ),
-    makeFn("add", [FRTypeDate, FRTypeTimeDuration], (inputs) =>
-      switch inputs {
-        | [IEvDate(d1), IEvTimeDuration(d2)] => 
-            IEvDate(DateTime.Date.addDuration(d1, d2))->Ok
-        | _ => Error(impossibleError)
-      }
-    ),
-    makeFn("toString", [FRTypeTimeDuration], (inputs) =>
-      switch inputs {
-        | [IEvTimeDuration(t)] => IEvString(DateTime.Duration.toString(t))->Ok
-        | _ => Error(impossibleError)
-      }
-    ),
-    makeNumberToDurationFn("minutes", DateTime.Duration.fromMinutes),
-    makeNumberToDurationFn("fromUnit_minutes", DateTime.Duration.fromMinutes),
-    makeNumberToDurationFn("hours", DateTime.Duration.fromHours),
-    makeNumberToDurationFn("fromUnit_hours", DateTime.Duration.fromHours),
-    makeNumberToDurationFn("days", DateTime.Duration.fromDays),
-    makeNumberToDurationFn("fromUnit_days", DateTime.Duration.fromDays),
-    makeNumberToDurationFn("years", DateTime.Duration.fromYears),
-    makeNumberToDurationFn("fromUnit_years", DateTime.Duration.fromYears),
-    makeDurationToNumberFn("toMinutes", DateTime.Duration.toMinutes),
-    makeDurationToNumberFn("toHours", DateTime.Duration.toHours),
-    makeDurationToNumberFn("toDays", DateTime.Duration.toDays),
-    makeDurationToNumberFn("toYears", DateTime.Duration.toYears),
-    makeFn("add", [FRTypeTimeDuration, FRTypeTimeDuration], (inputs) =>
-      switch inputs {
-        | [IEvTimeDuration(d1), IEvTimeDuration(d2)] => IEvTimeDuration(DateTime.Duration.add(d1, d2))->Ok
-        | _ => Error(impossibleError)
-      }
-    ),
-    makeFn("subtract", [FRTypeTimeDuration, FRTypeTimeDuration], (inputs) =>
-      switch inputs {
-        | [IEvTimeDuration(d1), IEvTimeDuration(d2)] => IEvTimeDuration(DateTime.Duration.subtract(d1, d2))->Ok
-        | _ => Error(impossibleError)
-      }
-    ),
-    makeFn("multiply", [FRTypeTimeDuration, FRTypeNumber], (inputs) =>
-      switch inputs {
-        | [IEvTimeDuration(d1), IEvNumber(d2)] => IEvTimeDuration(DateTime.Duration.multiply(d1, d2))->Ok
-        | _ => Error(impossibleError)
-      }
-    ),
-    makeFn("divide", [FRTypeTimeDuration, FRTypeNumber], (inputs) =>
-      switch inputs {
-        | [IEvTimeDuration(d1), IEvNumber(d2)] => IEvTimeDuration(DateTime.Duration.divide(d1, d2))->Ok
-        | _ => Error(impossibleError)
-      }
-    ),
-    makeFn("divide", [FRTypeTimeDuration, FRTypeTimeDuration], (inputs) =>
-      switch inputs {
-        | [IEvTimeDuration(d1), IEvTimeDuration(d2)] => IEvNumber(d1 /. d2)->Ok
-        | _ => Error(impossibleError)
-      }
-    ),
-]
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Mathjs.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Mathjs.res
deleted file mode 100644
index c1141545..00000000
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Mathjs.res
+++ /dev/null
@@ -1,38 +0,0 @@
-open FunctionRegistry_Core
-open FunctionRegistry_Helpers
-
-// FIXME - copy-pasted (see FR_Date.res and others)
-let makeFn = (
-  name: string,
-  inputs: array<frType>,
-  fn: array<internalExpressionValue> => result<internalExpressionValue, errorValue>
-) =>
-  Function.make(
-    ~name,
-    ~nameSpace="",
-    ~requiresNamespace=false,
-    ~definitions=[
-      FnDefinition.make(~name, ~inputs, ~run=(inputs, _, _, _) => fn(inputs), ())
-    ],
-    ()
-  )
-
-@module("mathjs") external dummy_: string => unit = "evaluate"
-let dummy1_ = dummy_ //Deceive the compiler to make the import although we wont make a call from rescript. Otherwise the optimizer deletes the import
-
-let mathjsFactorial: float => 'a = %raw(`function (expr) { return Mathjs.factorial(expr); }`)
-
-let library = [
-  // TODO - other MathJS
-  // https://mathjs.org/docs/reference/functions.html
-  makeFn(
-    "factorial",
-    [FRTypeNumber],
-    inputs => {
-      switch inputs {
-      | [IEvNumber(x)] => mathjsFactorial(x)->Reducer_Js_Gate.jsToIEv
-      | _ => Error(impossibleError)
-      }
-    }
-  ),
-]
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/README.md b/packages/squiggle-lang/src/rescript/FunctionRegistry/README.md
index e974b189..cf22d878 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/README.md
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/README.md
@@ -42,5 +42,7 @@ Key types, internal functionality, and a `Registry` module with a `matchAndRun`
 **FunctionRegistry_Library**
 A list of all the Functions defined in the Function Registry.
 
+The definition arrays are stored in `FR_*` modules, by convention.
+
 **FunctionRegistry_Helpers**
 A list of helper functions for the FunctionRegistry_Library.
diff --git a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Bindings.res b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Bindings.res
new file mode 100644
index 00000000..4ca31638
--- /dev/null
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Bindings.res
@@ -0,0 +1,89 @@
+/*
+  Bindings describe the entire set of bound variables accessible to the squiggle code.
+  Bindings objects are stored as linked lists of scopes:
+  { localX: ..., localY: ... } <- { globalZ: ..., ... } <- { importedT: ..., ... } <- { stdlibFunction: ..., ... }
+*/
+
+type t = Reducer_T.bindings
+type internalExpressionValue = Reducer_T.value
+
+let rec get = ({namespace, parent}: t, id: string) => {
+  switch namespace->Reducer_Namespace.get(id) {
+  | Some(v) => Some(v)
+  | None =>
+    switch parent {
+    | Some(p) => p->get(id)
+    | None => None
+    }
+  }
+}
+
+let set = ({namespace} as bindings: t, id: string, value): t => {
+  {
+    ...bindings,
+    namespace: namespace->Reducer_Namespace.set(id, value),
+  }
+}
+
+let rec toString = ({namespace, parent}: t) => {
+  let pairs = namespace->Reducer_Namespace.toString
+
+  switch parent {
+  | Some(p) => `{${pairs}} / ${toString(p)}`
+  | None => `{${pairs}}`
+  }
+}
+
+let extend = (bindings: t): t => {namespace: Reducer_Namespace.make(), parent: bindings->Some}
+
+let make = (): t => {namespace: Reducer_Namespace.make(), parent: None}
+
+let removeResult = ({namespace} as bindings: t): t => {
+  ...bindings,
+  namespace: namespace->Belt.Map.String.remove("__result__"),
+}
+
+let locals = ({namespace}: t): Reducer_T.namespace => namespace
+
+let fromNamespace = (namespace: Reducer_Namespace.t): t => {namespace: namespace, parent: None}
+
+// let typeAliasesKey = "_typeAliases_"
+// let typeReferencesKey = "_typeReferences_"
+
+// let getType = (NameSpace(container): t, id: string) => {
+//   Belt.Map.String.get(container, typeAliasesKey)->Belt.Option.flatMap(aliases =>
+//     switch aliases {
+//     | IEvRecord(r) => Belt.Map.String.get(r, id)
+//     | _ => None
+//     }
+//   )
+// }
+
+// let getTypeOf = (NameSpace(container): t, id: string) => {
+//   Belt.Map.String.get(container, typeReferencesKey)->Belt.Option.flatMap(defs =>
+//     switch defs {
+//     | IEvRecord(r) => Belt.Map.String.get(r, id)
+//     | _ => None
+//     }
+//   )
+// }
+
+// let setTypeAlias = (NameSpace(container): t, id: string, value): t => {
+//   let rValue = Belt.Map.String.getWithDefault(container, typeAliasesKey, IEvRecord(emptyMap))
+//   let r = switch rValue {
+//   | IEvRecord(r) => r
+//   | _ => emptyMap
+//   }
+//   let r2 = Belt.Map.String.set(r, id, value)->IEvRecord
+//   NameSpace(Belt.Map.String.set(container, typeAliasesKey, r2))
+// }
+
+// let setTypeOf = (NameSpace(container): t, id: string, value): t => {
+//   let rValue = Belt.Map.String.getWithDefault(container, typeReferencesKey, IEvRecord(emptyMap))
+//   let r = switch rValue {
+//   | IEvRecord(r) => r
+//   | _ => emptyMap
+//   }
+//   let r2 = Belt.Map.String.set(r, id, value)->IEvRecord
+//   NameSpace(Belt.Map.String.set(container, typeReferencesKey, r2))
+// }
diff --git a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Bindings/Reducer_Bindings.res b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Bindings/Reducer_Bindings.res
deleted file mode 100644
index c00dbe5c..00000000
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Bindings/Reducer_Bindings.res
+++ /dev/null
@@ -1,141 +0,0 @@
-// Only Bindings as the global module is supported
-// Other module operations such as import export will be preprocessed jobs
-
-module ExpressionT = Reducer_Expression_T
-module T = Reducer_T
-
-type t = Reducer_T.bindings
-type internalExpressionValue = Reducer_T.value
-
-let rec get = ({ namespace, parent }: t, id: string) => {
-  switch namespace->Reducer_Namespace.get(id) {
-  | Some(v) => Some(v)
-  | None =>
-    switch parent {
-    | Some(p) => get(p, id)
-    | None => None
-    }
-  }
-}
-
-let set = ({ namespace } as bindings: t, id: string, value): t => {
-  {
-    ...bindings,
-    namespace: namespace->Reducer_Namespace.set(id, value),
-  }
-}
-
-let rec toString = ({ namespace, parent }: t) => {
-  let pairs = namespace->Reducer_Namespace.toString
-
-  switch parent {
-  | Some(p) => `{${pairs}} / ${toString(p)}`
-  | None => `{${pairs}}`
-  }
-}
-
-let extend = (bindings: t): t => { namespace: Reducer_Namespace.make(), parent: bindings->Some }
-
-let make = (): t => { namespace: Reducer_Namespace.make(), parent: None }
-
-let removeResult = ({ namespace } as bindings: t): t => {
-  ...bindings,
-  namespace: namespace->Belt.Map.String.remove("__result__"),
-}
-
-let locals = ({ namespace }: t): Reducer_T.namespace => namespace
-
-let fromNamespace = (namespace: Reducer_Namespace.t): t => { namespace, parent: None }
-
-// let typeAliasesKey = "_typeAliases_"
-// let typeReferencesKey = "_typeReferences_"
-
-// let getType = (NameSpace(container): t, id: string) => {
-//   Belt.Map.String.get(container, typeAliasesKey)->Belt.Option.flatMap(aliases =>
-//     switch aliases {
-//     | IEvRecord(r) => Belt.Map.String.get(r, id)
-//     | _ => None
-//     }
-//   )
-// }
-
-// let getTypeOf = (NameSpace(container): t, id: string) => {
-//   Belt.Map.String.get(container, typeReferencesKey)->Belt.Option.flatMap(defs =>
-//     switch defs {
-//     | IEvRecord(r) => Belt.Map.String.get(r, id)
-//     | _ => None
-//     }
-//   )
-// }
-
-// let setTypeAlias = (NameSpace(container): t, id: string, value): t => {
-//   let rValue = Belt.Map.String.getWithDefault(container, typeAliasesKey, IEvRecord(emptyMap))
-//   let r = switch rValue {
-//   | IEvRecord(r) => r
-//   | _ => emptyMap
-//   }
-//   let r2 = Belt.Map.String.set(r, id, value)->IEvRecord
-//   NameSpace(Belt.Map.String.set(container, typeAliasesKey, r2))
-// }
-
-// let setTypeOf = (NameSpace(container): t, id: string, value): t => {
-//   let rValue = Belt.Map.String.getWithDefault(container, typeReferencesKey, IEvRecord(emptyMap))
-//   let r = switch rValue {
-//   | IEvRecord(r) => r
-//   | _ => emptyMap
-//   }
-//   let r2 = Belt.Map.String.set(r, id, value)->IEvRecord
-//   NameSpace(Belt.Map.String.set(container, typeReferencesKey, r2))
-// }
-
-// let functionNotFoundError = (call: functionCall) =>
-//   REFunctionNotFound(call->functionCallToCallSignature->functionCallSignatureToString)->Error
-
-// let functionNotFoundErrorFFIFn = (functionName: string): ExpressionT.ffiFn => {
-//   (args: array<internalExpressionValue>, _environment: environment): result<
-//     internalExpressionValue,
-//     errorValue,
-//   > => {
-//     let call = (functionName, args)
-//     functionNotFoundError(call)
-//   }
-// }
-
-// let convertOptionToFfiFnReturningResult = (
-//   myFunctionName: string,
-//   myFunction: ExpressionT.optionFfiFnReturningResult,
-// ): ExpressionT.ffiFn => {
-//   (args: array<InternalExpressionValue.t>, environment) => {
-//     myFunction(args, environment)->Belt.Option.getWithDefault(
-//       functionNotFoundErrorFFIFn(myFunctionName)(args, environment),
-//     )
-//   }
-// }
-
-// let convertOptionToFfiFn = (
-//   myFunctionName: string,
-//   myFunction: ExpressionT.optionFfiFn,
-// ): ExpressionT.ffiFn => {
-//   (args: array<InternalExpressionValue.t>, environment) => {
-//     myFunction(args, environment)
-//     ->Belt.Option.map(v => v->Ok)
-//     ->Belt.Option.getWithDefault(functionNotFoundErrorFFIFn(myFunctionName)(args, environment))
-//   }
-// }
-
-// -- Module definition
-// let define = (NameSpace(container): t, identifier: string, ev: internalExpressionValue): t => {
-//   NameSpace(Belt.Map.String.set(container, identifier, ev))
-// }
-
-// let defineNumber = (nameSpace: t, identifier: string, value: float): t =>
-//   nameSpace->define(identifier, IEvNumber(value))
-
-// let defineString = (nameSpace: t, identifier: string, value: string): t =>
-//   nameSpace->define(identifier, IEvString(value))
-
-// let defineBool = (nameSpace: t, identifier: string, value: bool): t =>
-//   nameSpace->define(identifier, IEvBool(value))
-
-// let defineModule = (nameSpace: t, identifier: string, value: t): t =>
-//   nameSpace->define(identifier, toExpressionValue(value))
diff --git a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltIn.res b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltIn.res
deleted file mode 100644
index 1ef4a543..00000000
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltIn.res
+++ /dev/null
@@ -1,148 +0,0 @@
-module Bindings = Reducer_Bindings
-// module Continuation = ReducerInterface_Value_Continuation
-module ExpressionT = Reducer_Expression_T
-module ExternalLibrary = ReducerInterface.ExternalLibrary
-module InternalExpressionValue = ReducerInterface_InternalExpressionValue
-module Lambda = Reducer_Expression_Lambda
-module MathJs = Reducer_MathJs
-module Result = Belt.Result
-module TypeBuilder = Reducer_Type_TypeBuilder
-
-module IEV = ReducerInterface_InternalExpressionValue
-
-open Reducer_ErrorValue
-
-/*
-  MathJs provides default implementations for built-ins
-  This is where all the expected built-ins like + = * / sin cos log ln etc are handled
-  DO NOT try to add external function mapping here!
-*/
-
-//TODO: pow to xor
-
-exception TestRescriptException
-
-let callInternal = (
-  call: IEV.functionCall,
-  _: Reducer_T.environment,
-  _: Reducer_T.reducerFn,
-): result<'b, errorValue> => {
-  let callMathJs = (call: IEV.functionCall): result<'b, errorValue> =>
-    switch call {
-    | ("javascriptraise", [msg]) => Js.Exn.raiseError(IEV.toString(msg)) // For Tests
-    | ("rescriptraise", _) => raise(TestRescriptException) // For Tests
-    | call => call->IEV.toStringFunctionCall->MathJs.Eval.eval
-    }
-
-  // let doAddArray = (originalA, b) => {
-  //   let a = originalA->Js.Array2.copy
-  //   let _ = Js.Array2.pushMany(a, b)
-  //   a->Reducer_T.IEvArray->Ok
-  // }
-  // let doAddString = (a, b) => {
-  //   let answer = Js.String2.concat(a, b)
-  //   answer->Reducer_T.IEvString->Ok
-  // }
-
-  let inspect = (value: Reducer_T.value) => {
-    Js.log(value->IEV.toString)
-    value->Ok
-  }
-
-  let inspectLabel = (value: Reducer_T.value, label: string) => {
-    Js.log(`${label}: ${value->IEV.toString}`)
-    value->Ok
-  }
-
-  // let doSetTypeAliasBindings = (
-  //   bindings: nameSpace,
-  //   symbol: string,
-  //   value: internalExpressionValue,
-  // ) => Bindings.setTypeAlias(bindings, symbol, value)->IEvBindings->Ok
-
-  // let doSetTypeOfBindings = (bindings: nameSpace, symbol: string, value: internalExpressionValue) =>
-  //   Bindings.setTypeOf(bindings, symbol, value)->IEvBindings->Ok
-
-  // let doExportBindings = (bindings: nameSpace) => bindings->Bindings.toExpressionValue->Ok
-
-  // let doIdentity = (value: Reducer_T.value) => value->Ok
-
-  // let doDumpBindings = (continuation: Reducer_T.nameSpace, value: Reducer_T.value) => {
-  //   // let _ = Continuation.inspect(continuation, "doDumpBindings")
-  //   accessors.states.continuation = continuation->Bindings.set("__result__", value)
-  //   value->Ok
-  // }
-
-  switch call {
-  // | ("$_atIndex_$", [IEvArray(aValueArray), IEvNumber(fIndex)]) => arrayAtIndex(aValueArray, fIndex)
-  // | ("$_atIndex_$", [IEvBindings(dict), IEvString(sIndex)]) => moduleAtIndex(dict, sIndex)
-  // | ("$_atIndex_$", [IEvRecord(dict), IEvString(sIndex)]) => recordAtIndex(dict, sIndex)
-  // | ("$_constructArray_$", args) => IEvArray(args)->Ok
-  // | ("$_constructRecord_$", [IEvArray(arrayOfPairs)]) => constructRecord(arrayOfPairs)
-  // | ("$_exportBindings_$", [IEvBindings(nameSpace)]) => doExportBindings(nameSpace)
-  // | ("$_exportBindings_$", [evValue]) => doIdentity(evValue)
-  // | ("$_setBindings_$", [IEvBindings(nameSpace), IEvSymbol(symbol), value]) =>
-  //   doSetBindings(nameSpace, symbol, value)
-  // | ("$_setTypeAliasBindings_$", [IEvBindings(nameSpace), IEvTypeIdentifier(symbol), value]) =>
-  //   doSetTypeAliasBindings(nameSpace, symbol, value)
-  // | ("$_setTypeOfBindings_$", [IEvBindings(nameSpace), IEvSymbol(symbol), value]) =>
-  //   doSetTypeOfBindings(nameSpace, symbol, value)
-  // | ("$_dumpBindings_$", [IEvBindings(nameSpace), _, evValue]) => doDumpBindings(nameSpace, evValue)
-  // | ("$_typeModifier_memberOf_$", [IEvTypeIdentifier(typeIdentifier), IEvArray(arr)]) =>
-  //   TypeBuilder.typeModifier_memberOf(IEvTypeIdentifier(typeIdentifier), IEvArray(arr))
-  // | ("$_typeModifier_memberOf_$", [IEvType(typeRecord), IEvArray(arr)]) =>
-  //   TypeBuilder.typeModifier_memberOf_update(typeRecord, IEvArray(arr))
-  // | ("$_typeModifier_min_$", [IEvTypeIdentifier(typeIdentifier), value]) =>
-  //   TypeBuilder.typeModifier_min(IEvTypeIdentifier(typeIdentifier), value)
-  // | ("$_typeModifier_min_$", [IEvType(typeRecord), value]) =>
-  //   TypeBuilder.typeModifier_min_update(typeRecord, value)
-  // | ("$_typeModifier_max_$", [IEvTypeIdentifier(typeIdentifier), value]) =>
-  //   TypeBuilder.typeModifier_max(IEvTypeIdentifier(typeIdentifier), value)
-  // | ("$_typeModifier_max_$", [IEvType(typeRecord), value]) =>
-  //   TypeBuilder.typeModifier_max_update(typeRecord, value)
-  // | ("$_typeModifier_opaque_$", [IEvType(typeRecord)]) =>
-  //   TypeBuilder.typeModifier_opaque_update(typeRecord)
-  // | ("$_typeOr_$", [IEvArray(arr)]) => TypeBuilder.typeOr(IEvArray(arr))
-  // | ("$_typeFunction_$", [IEvArray(arr)]) => TypeBuilder.typeFunction(arr)
-  // | ("$_typeTuple_$", [IEvArray(elems)]) => TypeBuilder.typeTuple(elems)
-  // | ("$_typeArray_$", [elem]) => TypeBuilder.typeArray(elem)
-  // | ("$_typeRecord_$", [IEvRecord(propertyMap)]) => TypeBuilder.typeRecord(propertyMap)
-  // | ("concat", [IEvArray(aValueArray), IEvArray(bValueArray)]) =>
-  //   doAddArray(aValueArray, bValueArray)
-  // | ("concat", [IEvString(aValueString), IEvString(bValueString)]) =>
-  //   doAddString(aValueString, bValueString)
-  | ("inspect", [value, IEvString(label)]) => inspectLabel(value, label)
-  | ("inspect", [value]) => inspect(value)
-  | (_, [IEvBool(_)])
-  | (_, [IEvNumber(_)])
-  | (_, [IEvString(_)])
-  | (_, [IEvBool(_), IEvBool(_)])
-  | (_, [IEvNumber(_), IEvNumber(_)])
-  | (_, [IEvString(_), IEvString(_)]) =>
-    callMathJs(call)
-  | call =>
-    Error(
-      REFunctionNotFound(call->IEV.functionCallToCallSignature->IEV.functionCallSignatureToString),
-    ) // Report full type signature as error
-  }
-}
-/*
-  Reducer uses Result monad while reducing expressions
-*/
-let dispatch = (
-  call: IEV.functionCall,
-  env: Reducer_T.environment,
-  reducer: Reducer_T.reducerFn,
-): Reducer_T.value =>
-  try {
-    let (fn, args) = call
-
-    // There is a bug that prevents string match in patterns
-    // So we have to recreate a copy of the string
-    switch ExternalLibrary.dispatch((Js.String.make(fn), args), env, reducer, callInternal) {
-    | Ok(v) => v
-    | Error(e) => raise(ErrorException(e))
-    }
-  } catch {
-  | exn => Reducer_ErrorValue.fromException(exn)->Reducer_ErrorValue.toException
-  }
diff --git a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression.res b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression.res
index 1136990b..1bcdc030 100644
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression.res
@@ -13,47 +13,51 @@ let rec evaluate: T.reducerFn = (expression, context): (T.value, T.context) => {
   switch expression {
   | T.EBlock(statements) => {
       let innerContext = {...context, bindings: context.bindings->Bindings.extend}
-      let (value, _) = statements->Belt.Array.reduce(
-        (T.IEvVoid, innerContext),
-        ((_, currentContext), statement) => statement->evaluate(currentContext)
-      )
-      (value, context) // inner context can be dropped
+      let (value, _) =
+        statements->Belt.Array.reduce((T.IEvVoid, innerContext), ((_, currentContext), statement) =>
+          statement->evaluate(currentContext)
+        )
+      (value, context)
     }
 
   | T.EProgram(statements) => {
       // Js.log(`bindings: ${context.bindings->Bindings.locals->Reducer_Namespace.toString}`)
-      let (value, finalContext) = statements->Belt.Array.reduce(
-        (T.IEvVoid, context),
-        ((_, currentContext), statement) => statement->evaluate(currentContext))
+      let (value, finalContext) =
+        statements->Belt.Array.reduce((T.IEvVoid, context), ((_, currentContext), statement) =>
+          statement->evaluate(currentContext)
+        )
 
       // Js.log(`bindings after: ${finalContext.bindings->Bindings.locals->Reducer_Namespace.toString}`)
       (value, finalContext)
     }
 
   | T.EArray(elements) => {
-    let value = elements->Belt.Array.map(element => {
-      let (value, _) = evaluate(element, context)
-      value
-    })->T.IEvArray
-    (value, context)
-  }
+      let value =
+        elements
+        ->Belt.Array.map(element => {
+          let (value, _) = evaluate(element, context)
+          value
+        })
+        ->T.IEvArray
+      (value, context)
+    }
 
   | T.ERecord(pairs) => {
-    let value = 
-      pairs
-      ->Belt.Array.map(((eKey, eValue)) => {
-        let (key, _) = eKey->evaluate(context)
-        let keyString = switch key {
-        | IEvString(s) => s
-        | _ => REOther("Record keys must be strings")->Reducer_ErrorValue.ErrorException->raise
-        }
-        let (value, _) = eValue->evaluate(context)
-        (keyString, value)
-      })
-      ->Belt.Map.String.fromArray
-      ->T.IEvRecord
-    (value, context)
-  }
+      let value =
+        pairs
+        ->Belt.Array.map(((eKey, eValue)) => {
+          let (key, _) = eKey->evaluate(context)
+          let keyString = switch key {
+          | IEvString(s) => s
+          | _ => REOther("Record keys must be strings")->Reducer_ErrorValue.ErrorException->raise
+          }
+          let (value, _) = eValue->evaluate(context)
+          (keyString, value)
+        })
+        ->Belt.Map.String.fromArray
+        ->T.IEvRecord
+      (value, context)
+    }
 
   | T.EAssign(left, right) => {
       let (result, _) = right->evaluate(context)
@@ -62,7 +66,7 @@ let rec evaluate: T.reducerFn = (expression, context): (T.value, T.context) => {
         {
           ...context,
           bindings: context.bindings->Bindings.set(left, result),
-        }
+        },
       )
     }
 
@@ -82,8 +86,10 @@ let rec evaluate: T.reducerFn = (expression, context): (T.value, T.context) => {
       }
     }
 
-  | T.ELambda(parameters, body) =>
-    (Lambda.makeLambda(parameters, context.bindings, body)->T.IEvLambda, context)
+  | T.ELambda(parameters, body) => (
+      Lambda.makeLambda(parameters, context.bindings, body)->T.IEvLambda,
+      context,
+    )
 
   | T.ECall(fn, args) => {
       let (lambda, _) = fn->evaluate(context)
@@ -92,8 +98,14 @@ let rec evaluate: T.reducerFn = (expression, context): (T.value, T.context) => {
         argValue
       })
       switch lambda {
-      | T.IEvLambda(lambda) => (Lambda.doLambdaCall(lambda, argValues, context.environment, evaluate), context)
-      | _ =>  RENotAFunction(lambda->ReducerInterface_InternalExpressionValue.toString)->Reducer_ErrorValue.ErrorException->raise
+      | T.IEvLambda(lambda) => (
+          Lambda.doLambdaCall(lambda, argValues, context.environment, evaluate),
+          context,
+        )
+      | _ =>
+        RENotAFunction(lambda->ReducerInterface_InternalExpressionValue.toString)
+        ->Reducer_ErrorValue.ErrorException
+        ->raise
       }
     }
   }
diff --git a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_Lambda.res b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_Lambda.res
index f6cc4ffa..bb4e80c5 100644
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_Lambda.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_Lambda.res
@@ -34,13 +34,18 @@ let makeLambda = (
     }
 
     let localBindings = bindings->Reducer_Bindings.extend
-    let localBindingsWithParameters = parameters->Belt.Array.reduceWithIndex(
-      localBindings,
-      (currentBindings, parameter, index) => {
+    let localBindingsWithParameters = parameters->Belt.Array.reduceWithIndex(localBindings, (
+      currentBindings,
+      parameter,
+      index,
+    ) => {
       currentBindings->Reducer_Bindings.set(parameter, arguments[index])
     })
 
-    let (value, _) = reducer(body, {bindings: localBindingsWithParameters, environment: environment})
+    let (value, _) = reducer(
+      body,
+      {bindings: localBindingsWithParameters, environment: environment},
+    )
     value
   }
 
diff --git a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_T.res b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_T.res
index 1aa64246..365d0836 100644
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_T.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_T.res
@@ -7,17 +7,20 @@ module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 type t = Reducer_T.expression
 
 let commaJoin = values => values->Reducer_Extra_Array.intersperse(", ")->Js.String.concatMany("")
-let semicolonJoin = values => values->Reducer_Extra_Array.intersperse("; ")->Js.String.concatMany("")
+let semicolonJoin = values =>
+  values->Reducer_Extra_Array.intersperse("; ")->Js.String.concatMany("")
 
 /*
   Converts the expression to String
 */
 let rec toString = (expression: t) =>
   switch expression {
-  | EBlock(statements) => `{${Js.Array2.map(statements, aValue => toString(aValue))->semicolonJoin}}`
+  | EBlock(statements) =>
+    `{${Js.Array2.map(statements, aValue => toString(aValue))->semicolonJoin}}`
   | EProgram(statements) => Js.Array2.map(statements, aValue => toString(aValue))->semicolonJoin
   | EArray(aList) => `[${Js.Array2.map(aList, aValue => toString(aValue))->commaJoin}]`
-  | ERecord(map) => `{${map->Belt.Array.map(((key, value)) => `${key->toString}: ${value->toString}`)->commaJoin}}`
+  | ERecord(map) =>
+    `{${map->Belt.Array.map(((key, value)) => `${key->toString}: ${value->toString}`)->commaJoin}}`
   | ESymbol(name) => name
   | ETernary(predicate, trueCase, falseCase) =>
     `${predicate->toString} ? (${trueCase->toString}) : (${falseCase->toString})`
diff --git a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Namespace.res b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Namespace.res
index 638bdbcd..5793fe07 100644
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Namespace.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Namespace.res
@@ -1,9 +1,12 @@
+/*
+  Namespace is a flat mapping of names to Squiggle values.
+  The full context of variables accessible to Squiggle is called "bindings"; see Reducer_Bindings module for details on it.
+*/
 type t = Reducer_T.namespace
 
 let make = (): t => Belt.Map.String.empty
 
-let get = (namespace: t, id: string): option<Reducer_T.value> =>
-  namespace->Belt.Map.String.get(id)
+let get = (namespace: t, id: string): option<Reducer_T.value> => namespace->Belt.Map.String.get(id)
 
 let set = (namespace: t, id: string, value): t => {
   namespace->Belt.Map.String.set(id, value)
@@ -16,19 +19,18 @@ let mergeFrom = (from: t, to: t): t => {
 }
 
 let mergeMany = (namespaces: array<t>): t =>
-    Belt.Array.reduce(namespaces, make(), (acc, ns) => acc->mergeFrom(ns))
+  Belt.Array.reduce(namespaces, make(), (acc, ns) => acc->mergeFrom(ns))
 
 let toString = (namespace: t) =>
   namespace
   ->Belt.Map.String.toArray
-  ->Belt.Array.map(((eachKey, eachValue)) => `${eachKey}: ${eachValue->ReducerInterface_InternalExpressionValue.toString}`)
+  ->Belt.Array.map(((eachKey, eachValue)) =>
+    `${eachKey}: ${eachValue->ReducerInterface_InternalExpressionValue.toString}`
+  )
   ->Js.Array2.toString
 
-let fromArray = (a): t =>
-    Belt.Map.String.fromArray(a)
+let fromArray = (a): t => Belt.Map.String.fromArray(a)
 
-let toMap = (namespace: t): Reducer_T.map =>
-  namespace
+let toMap = (namespace: t): Reducer_T.map => namespace
 
-let toRecord = (namespace: t): Reducer_T.value =>
-    namespace->toMap->IEvRecord
+let toRecord = (namespace: t): Reducer_T.value => namespace->toMap->IEvRecord
diff --git a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Peggy/Reducer_Peggy_GeneratedParser.peggy b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Peggy/Reducer_Peggy_GeneratedParser.peggy
index 469fcba1..3bf11162 100644
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Peggy/Reducer_Peggy_GeneratedParser.peggy
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Peggy/Reducer_Peggy_GeneratedParser.peggy
@@ -11,7 +11,7 @@ zeroOMoreArgumentsBlockOrExpression = innerBlockOrExpression / lambda
 
 outerBlock 
   = statements:array_statements  finalExpression: (statementSeparator @expression)?
-    { if (finalExpression) statements.push(finalExpression) 
+    { if (finalExpression) statements.push(finalExpression)
       return h.nodeProgram(statements) }
   / finalExpression: expression
     { return h.nodeProgram([finalExpression]) }
@@ -23,7 +23,7 @@ innerBlockOrExpression
 
 quotedInnerBlock  
   = '{' _nl statements:array_statements  finalExpression: (statementSeparator @expression)  _nl '}'
-      { if (finalExpression) statements.push(finalExpression) 
+      { if (finalExpression) statements.push(finalExpression)
         return h.nodeBlock(statements) }
   / '{' _nl finalExpression: expression  _nl '}'
       { return h.nodeBlock([finalExpression]) }
diff --git a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Peggy/helpers.ts b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Peggy/helpers.ts
index 4dd66205..f24fd819 100644
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Peggy/helpers.ts
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Peggy/helpers.ts
@@ -1,8 +1,8 @@
 import { LocationRange } from "peggy";
 
 export const toFunction = {
+  "+": "add",
   "-": "subtract",
-  "->": "pipe",
   "!=": "unequal",
   ".-": "dotSubtract",
   ".*": "dotMultiply",
@@ -13,7 +13,6 @@ export const toFunction = {
   "/": "divide",
   "&&": "and",
   "^": "pow", // or xor
-  "+": "add",
   "<": "smaller",
   "<=": "smallerEq",
   "==": "equal",
diff --git a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExternalLibrary.res b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExternalLibrary.res
index 4ce11eea..0922c8a7 100644
--- a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExternalLibrary.res
+++ b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExternalLibrary.res
@@ -9,12 +9,11 @@ let dispatch = (
   reducer: Reducer_T.reducerFn,
   chain,
 ): result<Reducer_T.value, 'e> => {
-  E.A.O.firstSomeFn([
-    // () => ReducerInterface_GenericDistribution.dispatch(call, environment),
-    // () => ReducerInterface_Date.dispatch(call, environment),
-    // () => ReducerInterface_Duration.dispatch(call, environment),
-    // () => ReducerInterface_Number.dispatch(call, environment),
-    // () => FunctionRegistry_Library.dispatch(call, environment, reducer),
+  E.A.O.firstSomeFn([// () => ReducerInterface_GenericDistribution.dispatch(call, environment),
+  // () => ReducerInterface_Date.dispatch(call, environment),
+  // () => ReducerInterface_Duration.dispatch(call, environment),
+  // () => ReducerInterface_Number.dispatch(call, environment),
+  // () => FunctionRegistry_Library.dispatch(call, environment, reducer),
   ])->E.O2.defaultFn(() => chain(call, environment, reducer))
 }
 
diff --git a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_InternalExpressionValue.res b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_InternalExpressionValue.res
index 27b0a546..dd0d6e51 100644
--- a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_InternalExpressionValue.res
+++ b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_InternalExpressionValue.res
@@ -2,7 +2,6 @@
 // (value methods should be moved to Reducer_Value.res)
 
 module ErrorValue = Reducer_ErrorValue
-module Extra_Array = Reducer_Extra_Array
 type environment = GenericDist.env
 module T = Reducer_T
 
diff --git a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_StdLib.res b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_StdLib.res
index dc74135a..18957474 100644
--- a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_StdLib.res
+++ b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_StdLib.res
@@ -10,49 +10,37 @@ let internalStdLib: Reducer_T.namespace = {
     "$_atIndex_$",
     Reducer_Expression_Lambda.makeFFILambda((inputs, _, _) => {
       switch inputs {
-      | [IEvArray(aValueArray), IEvNumber(fIndex)] => switch Belt.Array.get(
-          aValueArray,
-          Belt.Int.fromFloat(fIndex),
-        ) {
+      | [IEvArray(aValueArray), IEvNumber(fIndex)] => {
+        let index = Belt.Int.fromFloat(fIndex) // TODO - fail on non-integer indices?
+
+        switch Belt.Array.get(aValueArray, index) {
         | Some(value) => value
         | None =>
-          REArrayIndexNotFound("Array index not found", Belt.Int.fromFloat(fIndex))
+          REArrayIndexNotFound("Array index not found", index)
           ->ErrorException
           ->raise
         }
-      | [IEvRecord(dict), IEvString(sIndex)] => switch Belt.Map.String.get(dict, sIndex) {
+      }
+      | [IEvRecord(dict), IEvString(sIndex)] =>
+        switch Belt.Map.String.get(dict, sIndex) {
         | Some(value) => value
-        | None => RERecordPropertyNotFound("Record property not found", sIndex)->ErrorException->raise
+        | None =>
+          RERecordPropertyNotFound("Record property not found", sIndex)->ErrorException->raise
         }
       | _ => REOther("Trying to access key on wrong value")->ErrorException->raise
       }
     })->Reducer_T.IEvLambda,
   )
 
-  let res = FunctionRegistry_Library.nonRegistryLambdas->Belt.Array.reduce(
-    res,
-    (cur, (name, lambda)) => {
-      cur->Reducer_Namespace.set(name, lambda->Reducer_T.IEvLambda)
-    }
-  )
-
-  // TODO:
-  // () => ReducerInterface_GenericDistribution.dispatch(call, environment),
-  // () => ReducerInterface_Date.dispatch(call, environment),
-  // () => ReducerInterface_Duration.dispatch(call, environment),
-  // () => ReducerInterface_Number.dispatch(call, environment),
+  let res = FunctionRegistry_Library.nonRegistryLambdas->Belt.Array.reduce(res, (
+    cur,
+    (name, lambda),
+  ) => {
+    cur->Reducer_Namespace.set(name, lambda->Reducer_T.IEvLambda)
+  })
 
   // Reducer_Dispatch_BuiltIn:
 
-  // [x] | ("$_atIndex_$", [IEvArray(aValueArray), IEvNumber(fIndex)]) => arrayAtIndex(aValueArray, fIndex)
-  // [ ] | ("$_atIndex_$", [IEvBindings(dict), IEvString(sIndex)]) => moduleAtIndex(dict, sIndex)
-  // [x] | ("$_atIndex_$", [IEvRecord(dict), IEvString(sIndex)]) => recordAtIndex(dict, sIndex)
-  // [x] | ("$_constructArray_$", args) => IEvArray(args)->Ok
-  // [x] | ("$_constructRecord_$", [IEvArray(arrayOfPairs)]) => constructRecord(arrayOfPairs)
-  // [ ] | ("concat", [IEvArray(aValueArray), IEvArray(bValueArray)]) => doAddArray(aValueArray, bValueArray)
-  // [ ] | ("concat", [IEvString(aValueString), IEvString(bValueString)]) => doAddString(aValueString, bValueString)
-  // [ ] | ("inspect", [value, IEvString(label)]) => inspectLabel(value, label)
-  // [ ] | ("inspect", [value]) => inspect(value)
   // [ ] | (_, [IEvBool(_)])
   // [ ] | (_, [IEvNumber(_)])
   // [ ] | (_, [IEvString(_)])
@@ -60,19 +48,20 @@ let internalStdLib: Reducer_T.namespace = {
   // [ ] | (_, [IEvNumber(_), IEvNumber(_)])
   // [ ] | (_, [IEvString(_), IEvString(_)]) => callMathJs(call)
 
-  let res = FunctionRegistry_Library.registry
-  ->FunctionRegistry_Core.Registry.allNames
-  ->Belt.Array.reduce(res, (cur, name) => {
-    cur->Reducer_Namespace.set(
-      name,
-      Reducer_Expression_Lambda.makeFFILambda((arguments, environment, reducer) => {
-        switch FunctionRegistry_Library.call(name, arguments, environment, reducer) {
-        | Ok(value) => value
-        | Error(error) => error->Reducer_ErrorValue.ErrorException->raise
-        }
-      })->Reducer_T.IEvLambda,
-    )
-  })
+  let res =
+    FunctionRegistry_Library.registry
+    ->FunctionRegistry_Core.Registry.allNames
+    ->Belt.Array.reduce(res, (cur, name) => {
+      cur->Reducer_Namespace.set(
+        name,
+        Reducer_Expression_Lambda.makeFFILambda((arguments, environment, reducer) => {
+          switch FunctionRegistry_Library.call(name, arguments, environment, reducer) {
+          | Ok(value) => value
+          | Error(error) => error->Reducer_ErrorValue.ErrorException->raise
+          }
+        })->Reducer_T.IEvLambda,
+      )
+    })
 
   res
 }
diff --git a/packages/squiggle-lang/src/rescript/ReducerProject/ReducerProject.res b/packages/squiggle-lang/src/rescript/ReducerProject/ReducerProject.res
index 12933e21..01996b32 100644
--- a/packages/squiggle-lang/src/rescript/ReducerProject/ReducerProject.res
+++ b/packages/squiggle-lang/src/rescript/ReducerProject/ReducerProject.res
@@ -166,23 +166,25 @@ let linkDependencies = (project: t, sourceId: string): Reducer_T.namespace => {
     Belt.Array.concatMany([
       [project->getStdLib],
       pastChain->Belt.Array.map(project->getBindings),
-      pastChain->Belt.Array.map(
-        id => Reducer_Namespace.fromArray([
-          ("__result__",
-          switch project->getResult(id) {
+      pastChain->Belt.Array.map(id =>
+        Reducer_Namespace.fromArray([
+          (
+            "__result__",
+            switch project->getResult(id) {
             | Ok(result) => result
             | Error(error) => error->Reducer_ErrorValue.ErrorException->raise
-          })
+            },
+          ),
         ])
       ),
-    ])
+    ]),
   )
 
   let includesAsVariables = project->getIncludesAsVariables(sourceId)
   Belt.Array.reduce(includesAsVariables, namespace, (acc, (variable, includeFile)) =>
     acc->Reducer_Namespace.set(
       variable,
-      project->getBindings(includeFile)->Reducer_Namespace.toRecord
+      project->getBindings(includeFile)->Reducer_Namespace.toRecord,
     )
   )
 }
@@ -190,7 +192,7 @@ let linkDependencies = (project: t, sourceId: string): Reducer_T.namespace => {
 let doLinkAndRun = (project: t, sourceId: string): unit => {
   let context = Reducer_Context.createContext(
     project->linkDependencies(sourceId),
-    project->getEnvironment
+    project->getEnvironment,
   )
   let newItem = project->getItem(sourceId)->ProjectItem.run(context)
   // Js.log("after run " ++ newItem.continuation->Reducer_Bindings.toString)
diff --git a/packages/squiggle-lang/src/rescript/ReducerProject/ReducerProject_ProjectItem.res b/packages/squiggle-lang/src/rescript/ReducerProject/ReducerProject_ProjectItem.res
index e51f7d4b..93d434a3 100644
--- a/packages/squiggle-lang/src/rescript/ReducerProject/ReducerProject_ProjectItem.res
+++ b/packages/squiggle-lang/src/rescript/ReducerProject/ReducerProject_ProjectItem.res
@@ -172,10 +172,14 @@ let failRun = (this: t, e: Reducer_ErrorValue.errorValue): t =>
 
 let doRun = (this: t, context: Reducer_T.context): t =>
   switch this->getExpression {
-  | Some(expressionResult) => switch expressionResult {
-    | Ok(expression) => try {
+  | Some(expressionResult) =>
+    switch expressionResult {
+    | Ok(expression) =>
+      try {
         let (result, contextAfterEvaluation) = Reducer_Expression.evaluate(expression, context)
-        this->setResult(result->Ok)->setContinuation(contextAfterEvaluation.bindings->Reducer_Bindings.locals)
+        this
+        ->setResult(result->Ok)
+        ->setContinuation(contextAfterEvaluation.bindings->Reducer_Bindings.locals)
       } catch {
       | Reducer_ErrorValue.ErrorException(e) => this->failRun(e)
       | _ => this->failRun(RETodo("unhandled rescript exception"))
diff --git a/packages/squiggle-lang/src/rescript/SquiggleLibrary/SquiggleLibrary_Math.res b/packages/squiggle-lang/src/rescript/SquiggleLibrary/SquiggleLibrary_Math.res
index 4682fa01..631b05fb 100644
--- a/packages/squiggle-lang/src/rescript/SquiggleLibrary/SquiggleLibrary_Math.res
+++ b/packages/squiggle-lang/src/rescript/SquiggleLibrary/SquiggleLibrary_Math.res
@@ -12,4 +12,6 @@ let availableNumbers: array<(string, float)> = [
 ]
 
 let make = (): Reducer_Namespace.t =>
-  availableNumbers->E.A2.fmap(((name, v)) => (name, Reducer_T.IEvNumber(v)))->Reducer_Namespace.fromArray
+  availableNumbers
+  ->E.A2.fmap(((name, v)) => (name, Reducer_T.IEvNumber(v)))
+  ->Reducer_Namespace.fromArray