diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res
index 5e9e877e..fcb27cbe 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res
@@ -56,8 +56,8 @@ module FRType = {
     | FRTypeOption(v) => `option(${toString(v)})`
     }
 
-  let rec matchWithExpressionValue = (input: t, r: expressionValue): option<frValue> =>
-    switch (input, r) {
+  let rec matchWithExpressionValue = (t: t, r: expressionValue): option<frValue> =>
+    switch (t, r) {
     | (FRTypeNumber, EvNumber(f)) => Some(FRValueNumber(f))
     | (FRTypeDistOrNumber, EvNumber(f)) => Some(FRValueDistOrNumber(FRValueNumber(f)))
     | (FRTypeDistOrNumber, EvDistribution(Symbolic(#Float(f)))) =>
@@ -94,6 +94,11 @@ module FRType = {
   }
 }
 
+/*
+  This module, Matcher, is fairly lengthy. However, only two functions from it
+  are meant to be used outside of it. These are findMatches and matchToDef in Matches.Registry.
+  The rest of it is just called from those two functions.
+*/
 module Matcher = {
   module MatchSimple = {
     type t = DifferentName | SameNameDifferentArguments | FullMatch
@@ -185,21 +190,18 @@ module Matcher = {
   }
 
   module Registry = {
-    let findExactMatches = (r: registry, fnName: string, args: array<expressionValue>) => {
+    let _findExactMatches = (r: registry, fnName: string, args: array<expressionValue>) => {
       let functionMatchPairs = r->E.A2.fmap(l => (l, Function.match(l, fnName, args)))
-      let getFullMatch = E.A.getBy(functionMatchPairs, ((_, match: Function.match)) =>
-        Match.isFullMatch(match)
-      )
-      let fullMatch: option<RegistryMatch.match> = getFullMatch->E.O.bind(((fn, match)) =>
+      let fullMatch = functionMatchPairs->E.A.getBy(((_, match)) => Match.isFullMatch(match))
+      fullMatch->E.O.bind(((fn, match)) =>
         switch match {
         | FullMatch(index) => Some(RegistryMatch.makeMatch(fn.name, index))
         | _ => None
         }
       )
-      fullMatch
     }
 
-    let findNameMatches = (r: registry, fnName: string, args: array<expressionValue>) => {
+    let _findNameMatches = (r: registry, fnName: string, args: array<expressionValue>) => {
       let functionMatchPairs = r->E.A2.fmap(l => (l, Function.match(l, fnName, args)))
       let getNameMatches =
         functionMatchPairs
@@ -219,10 +221,10 @@ module Matcher = {
     }
 
     let findMatches = (r: registry, fnName: string, args: array<expressionValue>) => {
-      switch findExactMatches(r, fnName, args) {
+      switch _findExactMatches(r, fnName, args) {
       | Some(r) => Match.FullMatch(r)
       | None =>
-        switch findNameMatches(r, fnName, args) {
+        switch _findNameMatches(r, fnName, args) {
         | Some(r) => Match.SameNameDifferentArguments(r)
         | None => Match.DifferentName
         }
@@ -241,7 +243,10 @@ module Matcher = {
 module FnDefinition = {
   type t = fnDefinition
 
-  let defToString = (t: t) => t.inputs->E.A2.fmap(FRType.toString)->E.A2.joinWith(", ")
+  let toString = (t: t) => {
+    let inputs = t.inputs->E.A2.fmap(FRType.toString)->E.A2.joinWith(", ")
+    t.name ++ `(${inputs})`
+  }
 
   let run = (t: t, args: array<expressionValue>) => {
     let argValues = FRType.matchWithExpressionValueArray(t.inputs, args)
@@ -251,7 +256,7 @@ module FnDefinition = {
     }
   }
 
-  let make = (~name, ~inputs, ~run): fnDefinition => {
+  let make = (~name, ~inputs, ~run): t => {
     name: name,
     inputs: inputs,
     run: run,
@@ -259,7 +264,9 @@ module FnDefinition = {
 }
 
 module Function = {
-  let make = (~name, ~definitions): function => {
+  type t = function
+
+  let make = (~name, ~definitions): t => {
     name: name,
     definitions: definitions,
   }
@@ -278,7 +285,8 @@ module Registry = {
         matches
         ->E.A2.fmap(matchToDef)
         ->E.A.O.concatSomes
-        ->E.A2.fmap(r => `[${fnName}(${FnDefinition.defToString(r)})]`)
+        ->E.A2.fmap(FnDefinition.toString)
+        ->E.A2.fmap(r => `[${r}]`)
         ->E.A2.joinWith("; ")
       `There are function matches for ${fnName}(), but with different arguments: ${defs}`
     }
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Helpers.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Helpers.res
index 8ef27a6c..6daeace1 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Helpers.res
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Helpers.res
@@ -9,44 +9,43 @@ module Wrappers = {
 }
 
 module Prepare = {
-  let recordWithTwoArgsToValues = (inputs: array<frValue>): result<array<frValue>, string> =>
-    switch inputs {
-    | [FRValueRecord([(_, n1), (_, n2)])] => Ok([n1, n2])
-    | _ => Error(impossibleError)
-    }
+  type ts = array<frValue>
+  type err = string
 
-  let twoNumberInputs = (inputs: array<frValue>): result<(float, float), string> => {
-    switch inputs {
-    | [FRValueNumber(n1), FRValueNumber(n2)] => Ok(n1, n2)
-    | _ => Error(impossibleError)
+  module ToValueArray = {
+    module Record = {
+      let twoArgs = (inputs: ts): result<ts, err> =>
+        switch inputs {
+        | [FRValueRecord([(_, n1), (_, n2)])] => Ok([n1, n2])
+        | _ => Error(impossibleError)
+        }
     }
   }
 
-  let twoDistOrNumber = (values: array<frValue>): result<
-    (frValueDistOrNumber, frValueDistOrNumber),
-    string,
-  > => {
-    switch values {
-    | [FRValueDistOrNumber(a1), FRValueDistOrNumber(a2)] => Ok(a1, a2)
-    | _ => Error(impossibleError)
+  module ToValueTuple = {
+    let twoDistOrNumber = (values: ts): result<(frValueDistOrNumber, frValueDistOrNumber), err> => {
+      switch values {
+      | [FRValueDistOrNumber(a1), FRValueDistOrNumber(a2)] => Ok(a1, a2)
+      | _ => Error(impossibleError)
+      }
+    }
+
+    module Record = {
+      let twoDistOrNumber = (values: ts): result<(frValueDistOrNumber, frValueDistOrNumber), err> =>
+        values->ToValueArray.Record.twoArgs->E.R.bind(twoDistOrNumber)
     }
   }
-
-  let twoDistOrNumberFromRecord = (values: array<frValue>) =>
-    values->recordWithTwoArgsToValues->E.R.bind(twoDistOrNumber)
 }
 
 module Process = {
   let twoDistsOrNumbersToDist = (
     ~fn: ((float, float)) => result<DistributionTypes.genericDist, string>,
     ~values: (frValueDistOrNumber, frValueDistOrNumber),
-  ) => {
+  ): result<DistributionTypes.genericDist, string> => {
     let toSampleSet = r => GenericDist.toSampleSetDist(r, 1000)
-    let sampleSetToExpressionValue = (
-      b: Belt.Result.t<QuriSquiggleLang.SampleSetDist.t, QuriSquiggleLang.DistributionTypes.error>,
-    ) =>
+    let sampleSetToExpressionValue = (b: Belt.Result.t<SampleSetDist.t, DistributionTypes.error>) =>
       switch b {
-      | Ok(r) => Ok(ReducerInterface_ExpressionValue.EvDistribution(SampleSet(r)))
+      | Ok(r) => Ok(DistributionTypes.SampleSet(r))
       | Error(d) => Error(DistributionTypes.Error.toString(d))
       }
 
@@ -56,9 +55,11 @@ module Process = {
       | Error(r) => Error(Operation.Other(r))
       }
 
-    let singleVarSample = (a, fn) => {
+    let singleVarSample = (dist, fn) => {
       let sampleSetResult =
-        toSampleSet(a) |> E.R2.bind(dist =>
+        dist
+        ->toSampleSet
+        ->E.R.bind(dist =>
           SampleSetDist.samplesMap(
             ~fn=f => fn(f)->mapFnResult,
             dist,
@@ -68,7 +69,7 @@ module Process = {
     }
 
     switch values {
-    | (FRValueNumber(a1), FRValueNumber(a2)) => fn((a1, a2))->E.R2.fmap(Wrappers.evDistribution)
+    | (FRValueNumber(a1), FRValueNumber(a2)) => fn((a1, a2))
     | (FRValueDist(a1), FRValueNumber(a2)) => singleVarSample(a1, r => fn((r, a2)))
     | (FRValueNumber(a1), FRValueDist(a2)) => singleVarSample(a2, r => fn((a1, r)))
     | (FRValueDist(a1), FRValueDist(a2)) => {
@@ -89,17 +90,20 @@ module Process = {
     ~fn: ((float, float)) => result<SymbolicDistTypes.symbolicDist, string>,
     ~values,
   ) => {
-    twoDistsOrNumbersToDist(~fn=r => r->fn->E.R2.fmap(Wrappers.symbolic), ~values)
+    let newFn = r => fn(r)->E.R2.fmap(Wrappers.symbolic)
+    twoDistsOrNumbersToDist(~fn=newFn, ~values)
   }
 }
 
 module TwoArgDist = {
   let process = (~fn, r) =>
-    r->E.R.bind(Process.twoDistsOrNumbersToDistUsingSymbolicDist(~fn, ~values=_))
+    r
+    ->E.R.bind(Process.twoDistsOrNumbersToDistUsingSymbolicDist(~fn, ~values=_))
+    ->E.R2.fmap(Wrappers.evDistribution)
 
   let mkRegular = (name, fn) => {
     FnDefinition.make(~name, ~inputs=[FRTypeDistOrNumber, FRTypeDistOrNumber], ~run=inputs =>
-      inputs->Prepare.twoDistOrNumber->process(~fn)
+      inputs->Prepare.ToValueTuple.twoDistOrNumber->process(~fn)
     )
   }
 
@@ -107,7 +111,7 @@ module TwoArgDist = {
     FnDefinition.make(
       ~name,
       ~inputs=[FRTypeRecord([("p5", FRTypeDistOrNumber), ("p95", FRTypeDistOrNumber)])],
-      ~run=inputs => inputs->Prepare.twoDistOrNumberFromRecord->process(~fn),
+      ~run=inputs => inputs->Prepare.ToValueTuple.Record.twoDistOrNumber->process(~fn),
     )
   }
 
@@ -115,7 +119,7 @@ module TwoArgDist = {
     FnDefinition.make(
       ~name,
       ~inputs=[FRTypeRecord([("mean", FRTypeDistOrNumber), ("stdev", FRTypeDistOrNumber)])],
-      ~run=inputs => inputs->Prepare.twoDistOrNumberFromRecord->process(~fn),
+      ~run=inputs => inputs->Prepare.ToValueTuple.Record.twoDistOrNumber->process(~fn),
     )
   }
 }
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res
index d998191f..705da963 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res
@@ -1,7 +1,7 @@
 open FunctionRegistry_Core
 open FunctionRegistry_Helpers
 
-let twoArgs = (fn, (a1, a2)) => fn(a1, a2)
+let twoArgs = E.Tuple2.toFnCall
 
 module NormalFn = {
   let fnName = "normal"
@@ -56,4 +56,4 @@ let more = [
   ),
 ]
 
-let allFunctions = [NormalFn.toFn, LognormalFn.toFn]
+let allFunctions = E.A.append([NormalFn.toFn, LognormalFn.toFn], more)
diff --git a/packages/squiggle-lang/src/rescript/Utility/E.res b/packages/squiggle-lang/src/rescript/Utility/E.res
index 1916b8b1..3357f4f4 100644
--- a/packages/squiggle-lang/src/rescript/Utility/E.res
+++ b/packages/squiggle-lang/src/rescript/Utility/E.res
@@ -52,6 +52,7 @@ module Tuple2 = {
     let (_, b) = v
     b
   }
+  let toFnCall = (fn, (a1, a2)) => fn(a1, a2)
 }
 
 module O = {