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 80093afb..3440c3e0 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
@@ -110,15 +110,15 @@ describe("Peggy parse", () => {
   })
 
   describe("arrays", () => {
-    testParse("[]", "{(::$_endOfOuterBlock_$ () (::$_constructArray_$ ()))}")
-    testParse("[0, 1, 2]", "{(::$_endOfOuterBlock_$ () (::$_constructArray_$ (0 1 2)))}")
+    testParse("[]", "{(::$_endOfOuterBlock_$ () (::$_constructArray_$))}")
+    testParse("[0, 1, 2]", "{(::$_endOfOuterBlock_$ () (::$_constructArray_$ 0 1 2))}")
     testParse(
       "['hello', 'world']",
-      "{(::$_endOfOuterBlock_$ () (::$_constructArray_$ ('hello' 'world')))}",
+      "{(::$_endOfOuterBlock_$ () (::$_constructArray_$ 'hello' 'world'))}",
     )
     testParse(
       "([0,1,2])[1]",
-      "{(::$_endOfOuterBlock_$ () (::$_atIndex_$ (::$_constructArray_$ (0 1 2)) 1))}",
+      "{(::$_endOfOuterBlock_$ () (::$_atIndex_$ (::$_constructArray_$ 0 1 2) 1))}",
     )
   })
 
@@ -315,7 +315,7 @@ describe("Peggy parse", () => {
     )
     testParse(
       "myadd(x,y)=x+y; z=[myadd]; z",
-      "{:myadd = {|:x,:y| {(::add :x :y)}}; :z = {(::$_constructArray_$ (:myadd))}; (::$_endOfOuterBlock_$ () :z)}",
+      "{:myadd = {|:x,:y| {(::add :x :y)}}; :z = {(::$_constructArray_$ :myadd)}; (::$_endOfOuterBlock_$ () :z)}",
     )
     testParse(
       "myaddd(x,y)=x+y; z={x: myaddd}; z",
@@ -328,11 +328,11 @@ describe("Peggy parse", () => {
     )
     testParse(
       "map([1,2,3], {|x| x+1})",
-      "{(::$_endOfOuterBlock_$ () (::map (::$_constructArray_$ (1 2 3)) {|:x| {(::add :x 1)}}))}",
+      "{(::$_endOfOuterBlock_$ () (::map (::$_constructArray_$ 1 2 3) {|:x| {(::add :x 1)}}))}",
     )
     testParse(
       "[1,2,3]->map({|x| x+1})",
-      "{(::$_endOfOuterBlock_$ () (::map (::$_constructArray_$ (1 2 3)) {|:x| {(::add :x 1)}}))}",
+      "{(::$_endOfOuterBlock_$ () (::map (::$_constructArray_$ 1 2 3) {|:x| {(::add :x 1)}}))}",
     )
   })
   describe("unit", () => {
diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_Parse_type_test.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_Parse_type_test.res
index 010486be..d6425b66 100644
--- a/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_Parse_type_test.res
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_Parse_type_test.res
@@ -14,29 +14,29 @@ describe("Peggy parse type", () => {
   describe("type or", () => {
     testParse(
       "answer: number|string",
-      "{(::$_typeOf_$ :answer (::$_typeOr_$ (::$_constructArray_$ (#number #string)))); (::$_endOfOuterBlock_$ () ())}",
+      "{(::$_typeOf_$ :answer (::$_typeOr_$ (::$_constructArray_$ #number #string))); (::$_endOfOuterBlock_$ () ())}",
     )
   })
   describe("type function", () => {
     testParse(
       "f: number=>number=>number",
-      "{(::$_typeOf_$ :f (::$_typeFunction_$ (::$_constructArray_$ (#number #number #number)))); (::$_endOfOuterBlock_$ () ())}",
+      "{(::$_typeOf_$ :f (::$_typeFunction_$ (::$_constructArray_$ #number #number #number))); (::$_endOfOuterBlock_$ () ())}",
     )
   })
   describe("high priority contract", () => {
     testParse(
       "answer: number<-min<-max(100)|string",
-      "{(::$_typeOf_$ :answer (::$_typeOr_$ (::$_constructArray_$ ((::$_typeModifier_max_$ (::$_typeModifier_min_$ #number) 100) #string)))); (::$_endOfOuterBlock_$ () ())}",
+      "{(::$_typeOf_$ :answer (::$_typeOr_$ (::$_constructArray_$ (::$_typeModifier_max_$ (::$_typeModifier_min_$ #number) 100) #string))); (::$_endOfOuterBlock_$ () ())}",
     )
     testParse(
       "answer: number<-memberOf([1,3,5])",
-      "{(::$_typeOf_$ :answer (::$_typeModifier_memberOf_$ #number (::$_constructArray_$ (1 3 5)))); (::$_endOfOuterBlock_$ () ())}",
+      "{(::$_typeOf_$ :answer (::$_typeModifier_memberOf_$ #number (::$_constructArray_$ 1 3 5))); (::$_endOfOuterBlock_$ () ())}",
     )
   })
   describe("low priority contract", () => {
     testParse(
       "answer: number | string $ opaque",
-      "{(::$_typeOf_$ :answer (::$_typeModifier_opaque_$ (::$_typeOr_$ (::$_constructArray_$ (#number #string))))); (::$_endOfOuterBlock_$ () ())}",
+      "{(::$_typeOf_$ :answer (::$_typeModifier_opaque_$ (::$_typeOr_$ (::$_constructArray_$ #number #string)))); (::$_endOfOuterBlock_$ () ())}",
     )
   })
   describe("type array", () => {
@@ -54,32 +54,32 @@ describe("Peggy parse type", () => {
   describe("type constructor", () => {
     testParse(
       "answer: Age(number)",
-      "{(::$_typeOf_$ :answer (::$_typeConstructor_$ #Age (::$_constructArray_$ (#number)))); (::$_endOfOuterBlock_$ () ())}",
+      "{(::$_typeOf_$ :answer (::$_typeConstructor_$ #Age (::$_constructArray_$ #number))); (::$_endOfOuterBlock_$ () ())}",
     )
     testParse(
       "answer: Complex(number, number)",
-      "{(::$_typeOf_$ :answer (::$_typeConstructor_$ #Complex (::$_constructArray_$ (#number #number)))); (::$_endOfOuterBlock_$ () ())}",
+      "{(::$_typeOf_$ :answer (::$_typeConstructor_$ #Complex (::$_constructArray_$ #number #number))); (::$_endOfOuterBlock_$ () ())}",
     )
     testParse(
       "answer: Person({age: number, name: string})",
-      "{(::$_typeOf_$ :answer (::$_typeConstructor_$ #Person (::$_constructArray_$ ((::$_typeRecord_$ (::$_constructRecord_$ ('age': #number 'name': #string))))))); (::$_endOfOuterBlock_$ () ())}",
+      "{(::$_typeOf_$ :answer (::$_typeConstructor_$ #Person (::$_constructArray_$ (::$_typeRecord_$ (::$_constructRecord_$ ('age': #number 'name': #string)))))); (::$_endOfOuterBlock_$ () ())}",
     )
     testParse(
       "weekend: Saturday | Sunday",
-      "{(::$_typeOf_$ :weekend (::$_typeOr_$ (::$_constructArray_$ ((::$_typeConstructor_$ #Saturday (::$_constructArray_$ ())) (::$_typeConstructor_$ #Sunday (::$_constructArray_$ ())))))); (::$_endOfOuterBlock_$ () ())}",
+      "{(::$_typeOf_$ :weekend (::$_typeOr_$ (::$_constructArray_$ (::$_typeConstructor_$ #Saturday (::$_constructArray_$)) (::$_typeConstructor_$ #Sunday (::$_constructArray_$))))); (::$_endOfOuterBlock_$ () ())}",
     )
   })
   describe("type parenthesis", () => {
     //$ is introduced to avoid parenthesis
     testParse(
       "answer: (number|string)<-opaque",
-      "{(::$_typeOf_$ :answer (::$_typeModifier_opaque_$ (::$_typeOr_$ (::$_constructArray_$ (#number #string))))); (::$_endOfOuterBlock_$ () ())}",
+      "{(::$_typeOf_$ :answer (::$_typeModifier_opaque_$ (::$_typeOr_$ (::$_constructArray_$ #number #string)))); (::$_endOfOuterBlock_$ () ())}",
     )
   })
   describe("squiggle expressions in type contracts", () => {
     testParse(
       "odds1 = [1,3,5]; odds2 = [7, 9]; type odds = number<-memberOf(concat(odds1, odds2))",
-      "{:odds1 = {(::$_constructArray_$ (1 3 5))}; :odds2 = {(::$_constructArray_$ (7 9))}; (::$_typeAlias_$ #odds (::$_typeModifier_memberOf_$ #number (::concat :odds1 :odds2))); (::$_endOfOuterBlock_$ () ())}",
+      "{:odds1 = {(::$_constructArray_$ 1 3 5)}; :odds2 = {(::$_constructArray_$ 7 9)}; (::$_typeAlias_$ #odds (::$_typeModifier_memberOf_$ #number (::concat :odds1 :odds2))); (::$_endOfOuterBlock_$ () ())}",
     )
   })
 })
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 3b20fafc..eefa2294 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
@@ -54,22 +54,22 @@ describe("Peggy to Expression", () => {
   })
 
   describe("arrays", () => {
-    testToExpression("[]", "{(:$_endOfOuterBlock_$ () (:$_constructArray_$ ()))}", ~v="[]", ())
+    testToExpression("[]", "{(:$_endOfOuterBlock_$ () (:$_constructArray_$))}", ~v="[]", ())
     testToExpression(
       "[0, 1, 2]",
-      "{(:$_endOfOuterBlock_$ () (:$_constructArray_$ (0 1 2)))}",
+      "{(:$_endOfOuterBlock_$ () (:$_constructArray_$ 0 1 2))}",
       ~v="[0,1,2]",
       (),
     )
     testToExpression(
       "['hello', 'world']",
-      "{(:$_endOfOuterBlock_$ () (:$_constructArray_$ ('hello' 'world')))}",
+      "{(:$_endOfOuterBlock_$ () (:$_constructArray_$ 'hello' 'world'))}",
       ~v="['hello','world']",
       (),
     )
     testToExpression(
       "([0,1,2])[1]",
-      "{(:$_endOfOuterBlock_$ () (:$_atIndex_$ (:$_constructArray_$ (0 1 2)) 1))}",
+      "{(:$_endOfOuterBlock_$ () (:$_atIndex_$ (:$_constructArray_$ 0 1 2) 1))}",
       ~v="1",
       (),
     )
diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_type_test.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_type_test.res
index b0cfb676..9c4e7918 100644
--- a/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_type_test.res
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_type_test.res
@@ -21,7 +21,7 @@ describe("Peggy Types to Expression", () => {
   describe("type or", () => {
     testToExpression(
       "answer: number|string|distribution",
-      "{(:$_typeOf_$ :answer (:$_typeOr_$ (:$_constructArray_$ (#number #string #distribution)))); (:$_endOfOuterBlock_$ () ())}",
+      "{(:$_typeOf_$ :answer (:$_typeOr_$ (:$_constructArray_$ #number #string #distribution))); (:$_endOfOuterBlock_$ () ())}",
       // ~v="@{_typeReferences_: {answer: {typeOr: [#number,#string,#distribution],typeTag: 'typeOr'}}}",
       (),
     )
@@ -29,13 +29,13 @@ describe("Peggy Types to Expression", () => {
   describe("type function", () => {
     testToExpression(
       "f: number=>number=>number",
-      "{(:$_typeOf_$ :f (:$_typeFunction_$ (:$_constructArray_$ (#number #number #number)))); (:$_endOfOuterBlock_$ () ())}",
+      "{(:$_typeOf_$ :f (:$_typeFunction_$ (:$_constructArray_$ #number #number #number))); (:$_endOfOuterBlock_$ () ())}",
       // ~v="@{_typeReferences_: {f: {inputs: [#number,#number],output: #number,typeTag: 'typeFunction'}}}",
       (),
     )
     testToExpression(
       "f: number=>number",
-      "{(:$_typeOf_$ :f (:$_typeFunction_$ (:$_constructArray_$ (#number #number)))); (:$_endOfOuterBlock_$ () ())}",
+      "{(:$_typeOf_$ :f (:$_typeFunction_$ (:$_constructArray_$ #number #number))); (:$_endOfOuterBlock_$ () ())}",
       // ~v="@{_typeReferences_: {f: {inputs: [#number],output: #number,typeTag: 'typeFunction'}}}",
       (),
     )
@@ -43,13 +43,13 @@ describe("Peggy Types to Expression", () => {
   describe("high priority contract", () => {
     testToExpression(
       "answer: number<-min(1)<-max(100)|string",
-      "{(:$_typeOf_$ :answer (:$_typeOr_$ (:$_constructArray_$ ((:$_typeModifier_max_$ (:$_typeModifier_min_$ #number 1) 100) #string)))); (:$_endOfOuterBlock_$ () ())}",
+      "{(:$_typeOf_$ :answer (:$_typeOr_$ (:$_constructArray_$ (:$_typeModifier_max_$ (:$_typeModifier_min_$ #number 1) 100) #string))); (:$_endOfOuterBlock_$ () ())}",
       // ~v="@{_typeReferences_: {answer: {typeOr: [{max: 100,min: 1,typeIdentifier: #number,typeTag: 'typeIdentifier'},#string],typeTag: 'typeOr'}}}",
       (),
     )
     testToExpression(
       "answer: number<-memberOf([1,3,5])",
-      "{(:$_typeOf_$ :answer (:$_typeModifier_memberOf_$ #number (:$_constructArray_$ (1 3 5)))); (:$_endOfOuterBlock_$ () ())}",
+      "{(:$_typeOf_$ :answer (:$_typeModifier_memberOf_$ #number (:$_constructArray_$ 1 3 5))); (:$_endOfOuterBlock_$ () ())}",
       // ~v="@{_typeReferences_: {answer: {memberOf: [1,3,5],typeIdentifier: #number,typeTag: 'typeIdentifier'}}}",
       (),
     )
@@ -81,7 +81,7 @@ describe("Peggy Types to Expression", () => {
   describe("low priority contract", () => {
     testToExpression(
       "answer: number | string $ opaque",
-      "{(:$_typeOf_$ :answer (:$_typeModifier_opaque_$ (:$_typeOr_$ (:$_constructArray_$ (#number #string))))); (:$_endOfOuterBlock_$ () ())}",
+      "{(:$_typeOf_$ :answer (:$_typeModifier_opaque_$ (:$_typeOr_$ (:$_constructArray_$ #number #string)))); (:$_endOfOuterBlock_$ () ())}",
       // ~v="@{_typeReferences_: {answer: {opaque: true,typeOr: [#number,#string],typeTag: 'typeOr'}}}",
       (),
     )
@@ -89,7 +89,7 @@ describe("Peggy Types to Expression", () => {
   describe("squiggle expressions in type contracts", () => {
     testToExpression(
       "odds1 = [1,3,5]; odds2 = [7, 9]; type odds = number<-memberOf(concat(odds1, odds2))",
-      "{(:$_let_$ :odds1 {(:$_constructArray_$ (1 3 5))}); (:$_let_$ :odds2 {(:$_constructArray_$ (7 9))}); (:$_typeAlias_$ #odds (:$_typeModifier_memberOf_$ #number (:concat :odds1 :odds2))); (:$_endOfOuterBlock_$ () ())}",
+      "{(:$_let_$ :odds1 {(:$_constructArray_$ 1 3 5)}); (:$_let_$ :odds2 {(:$_constructArray_$ 7 9)}); (:$_typeAlias_$ #odds (:$_typeModifier_memberOf_$ #number (:concat :odds1 :odds2))); (:$_endOfOuterBlock_$ () ())}",
       // ~v="@{_typeAliases_: {odds: {memberOf: [1,3,5,7,9],typeIdentifier: #number,typeTag: 'typeIdentifier'}},odds1: [1,3,5],odds2: [7,9]}",
       (),
     )
diff --git a/packages/squiggle-lang/__tests__/Reducer/Reducer_constructArray_test.res b/packages/squiggle-lang/__tests__/Reducer/Reducer_constructArray_test.res
new file mode 100644
index 00000000..205d4883
--- /dev/null
+++ b/packages/squiggle-lang/__tests__/Reducer/Reducer_constructArray_test.res
@@ -0,0 +1,13 @@
+open Jest
+open Reducer_Peggy_TestHelpers
+
+describe("Construct Array", () => {
+  testToExpression("[1,2]", "{(:$_endOfOuterBlock_$ () (:$_constructArray_$ 1 2))}", ~v="[1,2]", ())
+  testToExpression("[]", "{(:$_endOfOuterBlock_$ () (:$_constructArray_$))}", ~v="[]", ())
+  testToExpression(
+    "f(x)=x; g(x)=x; [f, g]",
+    "{(:$_let_$ :f (:$$_lambda_$$ [x] {:x})); (:$_let_$ :g (:$$_lambda_$$ [x] {:x})); (:$_endOfOuterBlock_$ () (:$_constructArray_$ :f :g))}",
+    ~v="[lambda(x=>internal code),lambda(x=>internal code)]",
+    (),
+  )
+})
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
index bead1a93..bec4a0da 100644
--- 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
@@ -147,7 +147,7 @@ let callInternal = (
   | ("$_atIndex_$", [IEvArray(aValueArray), IEvNumber(fIndex)]) => arrayAtIndex(aValueArray, fIndex)
   | ("$_atIndex_$", [IEvBindings(dict), IEvString(sIndex)]) => moduleAtIndex(dict, sIndex)
   | ("$_atIndex_$", [IEvRecord(dict), IEvString(sIndex)]) => recordAtIndex(dict, sIndex)
-  | ("$_constructArray_$", [IEvArray(aValueArray)]) => IEvArray(aValueArray)->Ok
+  | ("$_constructArray_$", args) => IEvArray(args)->Ok
   | ("$_constructRecord_$", [IEvArray(arrayOfPairs)]) => constructRecord(arrayOfPairs)
   | ("$_exportBindings_$", [IEvBindings(nameSpace)]) => doExportBindings(nameSpace)
   | ("$_exportBindings_$", [evValue]) => doIdentity(evValue)
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 94975233..394796f5 100644
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Peggy/helpers.ts
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Peggy/helpers.ts
@@ -137,7 +137,7 @@ export function apply(fn: string, arg: AnyPeggyNode) {
   return makeFunctionCall(fn, [arg]);
 }
 export function constructArray(elems: AnyPeggyNode[]) {
-  return apply("$_constructArray_$", nodeExpression(elems));
+  return makeFunctionCall("$_constructArray_$", elems);
 }
 export function constructRecord(elems: AnyPeggyNode[]) {
   return apply("$_constructRecord_$", nodeExpression(elems));