diff --git a/packages/squiggle-lang/src/js/SqProject.ts b/packages/squiggle-lang/src/js/SqProject.ts
index eb54bc4a..9e79b564 100644
--- a/packages/squiggle-lang/src/js/SqProject.ts
+++ b/packages/squiggle-lang/src/js/SqProject.ts
@@ -111,4 +111,8 @@ export class SqProject {
   setEnvironment(environment: environment) {
     RSProject.setEnvironment(this._value, environment);
   }
+
+  getEnvironment(): environment {
+    return RSProject.getEnvironment(this._value);
+  }
 }
diff --git a/packages/squiggle-lang/src/rescript/ForTS/ForTS_ReducerProject.res b/packages/squiggle-lang/src/rescript/ForTS/ForTS_ReducerProject.res
index 5b48b8f7..dabd72a5 100644
--- a/packages/squiggle-lang/src/rescript/ForTS/ForTS_ReducerProject.res
+++ b/packages/squiggle-lang/src/rescript/ForTS/ForTS_ReducerProject.res
@@ -211,6 +211,10 @@ let evaluate = (sourceCode: string): (
 let setEnvironment = (project: reducerProject, environment: environment): unit =>
   project->Private.setEnvironment(environment)
 
+@genType
+let getEnvironment = (project: reducerProject): environment =>
+  project->Private.getEnvironment
+
 /*
 Foreign function interface is intentionally demolished.
 There is another way to do that: Umur.
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res
index 96f5b0a8..714456a8 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res
@@ -10,6 +10,8 @@ type rec frType =
   | FRTypeNumber
   | FRTypeBool
   | FRTypeNumeric
+  | FRTypeDate
+  | FRTypeTimeDuration
   | FRTypeDistOrNumber
   | FRTypeDist
   | FRTypeLambda
@@ -29,6 +31,8 @@ and frTypeRecordParam = (string, frType)
 type rec frValue =
   | FRValueNumber(float)
   | FRValueBool(bool)
+  | FRValueDate(Js.Date.t)
+  | FRValueTimeDuration(float)
   | FRValueDist(DistributionTypes.genericDist)
   | FRValueArray(array<frValue>)
   | FRValueDistOrNumber(frValueDistOrNumber)
@@ -65,15 +69,14 @@ type function = {
   isExperimental: bool,
 }
 
-type fnNameDict = Js.Dict.t<array<fnDefinition>>
-type registry = {functions: array<function>, fnNameDict: fnNameDict}
-
 module FRType = {
   type t = frType
   let rec toString = (t: t) =>
     switch t {
     | FRTypeNumber => "number"
     | FRTypeBool => "bool"
+    | FRTypeDate => "date"
+    | FRTypeTimeDuration => "duration"
     | FRTypeNumeric => "numeric"
     | FRTypeDist => "distribution"
     | FRTypeDistOrNumber => "distribution|number"
@@ -90,6 +93,7 @@ module FRType = {
     }
 
   let rec toFrValue = (r: internalExpressionValue): option<frValue> =>
+    // not all value variants are supported, but it's not important (we'll probably deprecate frValues soon anyway)
     switch r {
     | IEvNumber(f) => Some(FRValueNumber(f))
     | IEvString(f) => Some(FRValueString(f))
@@ -111,6 +115,8 @@ module FRType = {
     | (FRTypeString, IEvString(f)) => Some(FRValueString(f))
     | (FRTypeNumber, IEvNumber(f)) => Some(FRValueNumber(f))
     | (FRTypeBool, IEvBool(f)) => Some(FRValueBool(f))
+    | (FRTypeDate, IEvDate(f)) => Some(FRValueDate(f))
+    | (FRTypeTimeDuration, IEvTimeDuration(f)) => Some(FRValueTimeDuration(f))
     | (FRTypeDistOrNumber, IEvNumber(f)) => Some(FRValueDistOrNumber(FRValueNumber(f)))
     | (FRTypeDistOrNumber, IEvDistribution(Symbolic(#Float(f)))) =>
       Some(FRValueDistOrNumber(FRValueNumber(f)))
@@ -147,6 +153,8 @@ module FRType = {
     switch e {
     | FRValueNumber(f) => IEvNumber(f)
     | FRValueBool(f) => IEvBool(f)
+    | FRValueDate(f) => IEvDate(f)
+    | FRValueTimeDuration(f) => IEvTimeDuration(f)
     | FRValueDistOrNumber(FRValueNumber(n)) => IEvNumber(n)
     | FRValueDistOrNumber(FRValueDist(n)) => IEvDistribution(n)
     | FRValueDist(dist) => IEvDistribution(dist)
@@ -265,33 +273,44 @@ module Function = {
 }
 
 module Registry = {
+  type fnNameDict = Belt.Map.String.t<array<fnDefinition>>
+  type registry = {functions: array<function>, fnNameDict: fnNameDict}
+
   let toJson = (r: registry) => r.functions->E.A2.fmap(Function.toJson)
   let allExamples = (r: registry) => r.functions->E.A2.fmap(r => r.examples)->E.A.concatMany
   let allExamplesWithFns = (r: registry) =>
     r.functions->E.A2.fmap(fn => fn.examples->E.A2.fmap(example => (fn, example)))->E.A.concatMany
 
+  let allNames = (r: registry) => r.fnNameDict->Belt.Map.String.keysToArray
+
   let _buildFnNameDict = (r: array<function>): fnNameDict => {
-    // Sorry for the imperative style of this. But it's much easier/less buggy than the previous version.
-    let res: fnNameDict = Js.Dict.empty()
-    r->Js.Array2.forEach(fn =>
-      fn.definitions->Js.Array2.forEach(def => {
+    // Three layers of reduce:
+    // 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) => {
         let names =
           [
             fn.nameSpace == "" ? [] : [`${fn.nameSpace}.${def.name}`],
             fn.requiresNamespace ? [] : [def.name],
           ]->E.A.concatMany
 
-        names->Js.Array2.forEach(name => {
-          switch res->Js.Dict.get(name) {
+        names->Belt.Array.reduce(acc, (acc, name) => {
+          switch acc->Belt.Map.String.get(name) {
           | Some(fns) => {
-              let _ = fns->Js.Array2.push(def)
+              let _ = fns->Js.Array2.push(def) // mutates the array, no need to update acc
+              acc
             }
-          | None => res->Js.Dict.set(name, [def])
+          | None => acc->Belt.Map.String.set(name, [def])
           }
         })
       })
     )
-    res
   }
 
   let make = (fns: array<function>): registry => {
@@ -306,7 +325,7 @@ module Registry = {
     env: Reducer_T.environment,
     reducer: Reducer_T.reducerFn,
   ): result<internalExpressionValue, errorValue> => {
-    switch Js.Dict.get(registry.fnNameDict, fnName) {
+    switch Belt.Map.String.get(registry.fnNameDict, fnName) {
     | Some(definitions) => {
         let showNameMatchDefinitions = () => {
           let defsString =
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res
index ce14c6da..34de2e2b 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res
@@ -11,6 +11,8 @@ let fnList = Belt.Array.concatMany([
   FR_Scoring.library,
   FR_GenericDist.library,
   FR_Units.library,
+  FR_Date.library,
+  FR_Mathjs.library,
 ])
 
 let registry = FunctionRegistry_Core.Registry.make(fnList)
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Builtin.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Builtin.res
index d5b79fc8..b3103add 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Builtin.res
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Builtin.res
@@ -51,8 +51,20 @@ let makeBinaryCmpFn = (name: string, fn: (float, float) => bool) => {
   )
 }
 
+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 = [
-  // TODO - other MathJS
   makeBinaryFn("add", (x, y) => x +. y),
   makeBinaryFn("subtract", (x, y) => x -. y),
   makeBinaryFn("multiply", (x, y) => x *. y),
@@ -63,6 +75,8 @@ let library = [
   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],
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Date.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Date.res
new file mode 100644
index 00000000..0e79d8cd
--- /dev/null
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Date.res
@@ -0,0 +1,155 @@
+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_GenericDist.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_GenericDist.res
index adb510cb..5b7d5dca 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_GenericDist.res
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_GenericDist.res
@@ -310,8 +310,6 @@ module Old = {
     | String(d) => Ok(IEvString(d))
     | Bool(d) => Ok(IEvBool(d))
     | FloatArray(d) => Ok(IEvArray(d |> E.A.fmap(r => Reducer_T.IEvNumber(r))))
-    // // FIXME - can't propagate error objects through FunctionRegistry
-    // | GenDistError(err) => Error(REDistributionError(err))
     | GenDistError(err) => Error(REDistributionError(err))
     }
 
@@ -370,8 +368,7 @@ let library = E.A.concatMany([
     makeProxyFn("max", [FRTypeDist]),
     makeProxyFn("mode", [FRTypeDist]),
     makeProxyFn("integralSum", [FRTypeDist]),
-    // // FIXME: doesn't work with Js.Dict in FunctionRegistry_Core
-    // makeProxyFn("toString", [FRTypeDist]),
+    makeProxyFn("toString", [FRTypeDist]),
     makeProxyFn("sparkline", [FRTypeDist]),
     makeProxyFn("sparkline", [FRTypeDist, FRTypeNumber]),
     makeProxyFn("exp", [FRTypeDist]),
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Mathjs.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Mathjs.res
new file mode 100644
index 00000000..c1141545
--- /dev/null
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Mathjs.res
@@ -0,0 +1,38 @@
+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/Reducer/Reducer_Expression/Reducer_Expression.res b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression.res
index bfaf993a..1136990b 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
@@ -93,7 +93,7 @@ let rec evaluate: T.reducerFn = (expression, context): (T.value, T.context) => {
       })
       switch lambda {
       | T.IEvLambda(lambda) => (Lambda.doLambdaCall(lambda, argValues, context.environment, evaluate), context)
-      | _ => REExpectedType("Lambda", "")->Reducer_ErrorValue.ErrorException->raise
+      | _ =>  RENotAFunction(lambda->ReducerInterface_InternalExpressionValue.toString)->Reducer_ErrorValue.ErrorException->raise
       }
     }
   }
diff --git a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_Date.res b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_Date.res
deleted file mode 100644
index bde1459f..00000000
--- a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_Date.res
+++ /dev/null
@@ -1,27 +0,0 @@
-module T = Reducer_T
-
-let dispatch = (
-  call: ReducerInterface_InternalExpressionValue.functionCall,
-  _: GenericDist.env,
-): option<result<T.value, Reducer_ErrorValue.errorValue>> => {
-  switch call {
-  | ("toString", [IEvDate(t)]) => T.IEvString(DateTime.Date.toString(t))->Ok->Some
-  | ("makeDateFromYear", [IEvNumber(year)]) =>
-    switch DateTime.Date.makeFromYear(year) {
-    | Ok(t) => T.IEvDate(t)->Ok->Some
-    | Error(e) => Reducer_ErrorValue.RETodo(e)->Error->Some
-    }
-  | ("dateFromNumber", [IEvNumber(f)]) => T.IEvDate(DateTime.Date.fromFloat(f))->Ok->Some
-  | ("toNumber", [IEvDate(f)]) => T.IEvNumber(DateTime.Date.toFloat(f))->Ok->Some
-  | ("subtract", [IEvDate(d1), IEvDate(d2)]) =>
-    switch DateTime.Date.subtract(d1, d2) {
-    | Ok(d) => T.IEvTimeDuration(d)->Ok
-    | Error(e) => Error(RETodo(e))
-    }->Some
-  | ("subtract", [IEvDate(d1), IEvTimeDuration(d2)]) =>
-    T.IEvDate(DateTime.Date.subtractDuration(d1, d2))->Ok->Some
-  | ("add", [IEvDate(d1), IEvTimeDuration(d2)]) =>
-    T.IEvDate(DateTime.Date.addDuration(d1, d2))->Ok->Some
-  | _ => None
-  }
-}
diff --git a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_Duration.res b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_Duration.res
deleted file mode 100644
index 889df52a..00000000
--- a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_Duration.res
+++ /dev/null
@@ -1,36 +0,0 @@
-module IEV = ReducerInterface_InternalExpressionValue
-module T = Reducer_T
-type internalExpressionValue = IEV.t
-
-let dispatch = (call: IEV.functionCall, _: T.environment): option<
-  result<Reducer_T.value, Reducer_ErrorValue.errorValue>,
-> => {
-  switch call {
-  | ("toString", [IEvTimeDuration(t)]) => T.IEvString(DateTime.Duration.toString(t))->Ok->Some
-  | ("minutes", [IEvNumber(f)]) => T.IEvTimeDuration(DateTime.Duration.fromMinutes(f))->Ok->Some
-  | ("fromUnit_minutes", [IEvNumber(f)]) =>
-    T.IEvTimeDuration(DateTime.Duration.fromMinutes(f))->Ok->Some
-  | ("hours", [IEvNumber(f)]) => T.IEvTimeDuration(DateTime.Duration.fromHours(f))->Ok->Some
-  | ("fromUnit_hours", [IEvNumber(f)]) =>
-    T.IEvTimeDuration(DateTime.Duration.fromHours(f))->Ok->Some
-  | ("days", [IEvNumber(f)]) => T.IEvTimeDuration(DateTime.Duration.fromDays(f))->Ok->Some
-  | ("fromUnit_days", [IEvNumber(f)]) => T.IEvTimeDuration(DateTime.Duration.fromDays(f))->Ok->Some
-  | ("years", [IEvNumber(f)]) => T.IEvTimeDuration(DateTime.Duration.fromYears(f))->Ok->Some
-  | ("fromUnit_years", [IEvNumber(f)]) =>
-    T.IEvTimeDuration(DateTime.Duration.fromYears(f))->Ok->Some
-  | ("toHours", [IEvTimeDuration(f)]) => T.IEvNumber(DateTime.Duration.toHours(f))->Ok->Some
-  | ("toMinutes", [IEvTimeDuration(f)]) => T.IEvNumber(DateTime.Duration.toMinutes(f))->Ok->Some
-  | ("toDays", [IEvTimeDuration(f)]) => T.IEvNumber(DateTime.Duration.toDays(f))->Ok->Some
-  | ("toYears", [IEvTimeDuration(f)]) => T.IEvNumber(DateTime.Duration.toYears(f))->Ok->Some
-  | ("add", [IEvTimeDuration(d1), IEvTimeDuration(d2)]) =>
-    T.IEvTimeDuration(DateTime.Duration.add(d1, d2))->Ok->Some
-  | ("subtract", [IEvTimeDuration(d1), IEvTimeDuration(d2)]) =>
-    T.IEvTimeDuration(DateTime.Duration.subtract(d1, d2))->Ok->Some
-  | ("multiply", [IEvTimeDuration(d1), IEvNumber(d2)]) =>
-    T.IEvTimeDuration(DateTime.Duration.multiply(d1, d2))->Ok->Some
-  | ("divide", [IEvTimeDuration(d1), IEvNumber(d2)]) =>
-    T.IEvTimeDuration(DateTime.Duration.divide(d1, d2))->Ok->Some
-  | ("divide", [IEvTimeDuration(d1), IEvTimeDuration(d2)]) => T.IEvNumber(d1 /. d2)->Ok->Some
-  | _ => None
-  }
-}
diff --git a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExternalLibrary.res b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExternalLibrary.res
index 6976471a..4ce11eea 100644
--- a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExternalLibrary.res
+++ b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExternalLibrary.res
@@ -11,8 +11,8 @@ let dispatch = (
 ): 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_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_StdLib.res b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_StdLib.res
index a3d41106..dc74135a 100644
--- a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_StdLib.res
+++ b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_StdLib.res
@@ -60,8 +60,8 @@ let internalStdLib: Reducer_T.namespace = {
   // [ ] | (_, [IEvNumber(_), IEvNumber(_)])
   // [ ] | (_, [IEvString(_), IEvString(_)]) => callMathJs(call)
 
-  let res = FunctionRegistry_Library.registry.fnNameDict
-  ->Js.Dict.keys
+  let res = FunctionRegistry_Library.registry
+  ->FunctionRegistry_Core.Registry.allNames
   ->Belt.Array.reduce(res, (cur, name) => {
     cur->Reducer_Namespace.set(
       name,
diff --git a/packages/squiggle-lang/src/rescript/Utility/Mathjs.res b/packages/squiggle-lang/src/rescript/Utility/Mathjs.res
deleted file mode 100644
index ccf43100..00000000
--- a/packages/squiggle-lang/src/rescript/Utility/Mathjs.res
+++ /dev/null
@@ -1,10 +0,0 @@
-// @module("./MathjsWrapper.js")
-// external parseMathExt: string => Js.Json.t = "parseMath"
-
-// let parseMath = (str: string): result<Js.Json.t, string> =>
-//   switch parseMathExt(str) {
-//   | exception Js.Exn.Error(err) => Error(Js.Exn.message(err) |> E.O.default("MathJS Parse Error"))
-//   | exception _ => Error("MathJS Parse Error")
-//   | j => Ok(j)
-//   }
-
diff --git a/packages/squiggle-lang/src/rescript/Utility/MathjsWrapper.js b/packages/squiggle-lang/src/rescript/Utility/MathjsWrapper.js
deleted file mode 100644
index 99bb3776..00000000
--- a/packages/squiggle-lang/src/rescript/Utility/MathjsWrapper.js
+++ /dev/null
@@ -1,9 +0,0 @@
-const math = require("mathjs");
-
-function parseMath(f) {
-  return JSON.parse(JSON.stringify(math.parse(f)));
-}
-
-module.exports = {
-  parseMath,
-};