diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry.res b/packages/squiggle-lang/src/rescript/FunctionRegistry.res
index df04cef9..a1138129 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry.res
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry.res
@@ -130,11 +130,12 @@ module Function = {
   type definitionId = int
   type match = Match.t<array<definitionId>, definitionId>
 
-  let make = (name, definitions): function => {
+  let make = (~name, ~definitions): function => {
     name: name,
     definitions: definitions,
   }
-  let makeDefinition = (name, inputs, run): fnDefinition => {
+
+  let makeDefinition = (~name, ~inputs, ~run): fnDefinition => {
     name: name,
     inputs: inputs,
     run: run,
@@ -239,39 +240,50 @@ module Registry = {
 
 let impossibleError = "Wrong inputs / Logically impossible"
 
-let twoNumberInputs = (inputs: array<value>) => {
-  switch inputs {
-  | [Number(n1), Number(n2)] => Ok(n1, n2)
-  | _ => Error(impossibleError)
+module Prepare = {
+  let twoNumberInputs = (inputs: array<value>) => {
+    switch inputs {
+    | [Number(n1), Number(n2)] => Ok(n1, n2)
+    | _ => Error(impossibleError)
+    }
   }
+
+  let twoDistOrNumber = (values: array<value>) => {
+    switch values {
+    | [DistOrNumber(a1), DistOrNumber(a2)] => Ok(a1, a2)
+    | _ => Error(impossibleError)
+    }
+  }
+
+  let twoNumberInputsRecord = (v1: string, v2: string, inputs: array<value>) =>
+    switch inputs {
+    | [Record([(name1, n1), (name2, n2)])] if name1 == v1 && name2 == v2 =>
+      twoNumberInputs([n1, n2])
+    | _ => Error(impossibleError)
+    }
+
+  let twoNumberInputsRecord2 = (inputs: array<value>) =>
+    switch inputs {
+    | [Record([(_, n1), (_, n2)])] => twoNumberInputs([n1, n2])
+    | _ => Error(impossibleError)
+    }
+
+  let twoNumberInputsRecord3 = (inputs: array<value>) =>
+    switch inputs {
+    | [Record([(_, n1), (_, n2)])] => Ok([n1, n2])
+    | _ => Error(impossibleError)
+    }
 }
 
-let twoNumberInputsRecord = (v1, v2, inputs: array<value>) =>
-  switch inputs {
-  | [Record([(name1, n1), (name2, n2)])] if name1 == v1 && name2 == v2 => twoNumberInputs([n1, n2])
-  | _ => Error(impossibleError)
-  }
-
-let contain = r => ReducerInterface_ExpressionValue.EvDistribution(Symbolic(r))
-
-let meanStdev = (mean, stdev) => SymbolicDist.Normal.make(mean, stdev)->E.R2.fmap(contain)
-
-let p5and95 = (p5, p95) => contain(SymbolicDist.Normal.from90PercentCI(p5, p95))
-
-let convertTwoInputs = (inputs: array<value>): result<expressionValue, string> =>
-  twoNumberInputs(inputs)->E.R.bind(((mean, stdev)) => meanStdev(mean, stdev))
-
-let twoDistOrStdev = (a1: value, a2: value) => {
-  switch (a1, a2) {
-  | (DistOrNumber(a1), DistOrNumber(a2)) => Ok(a1, a2)
-  | _ => Error(impossibleError)
-  }
+module Wrappers = {
+  let symbolic = r => DistributionTypes.Symbolic(r)
+  let evDistribution = r => ReducerInterface_ExpressionValue.EvDistribution(r)
+  let symbolicEvDistribution = r => r->Symbolic->evDistribution
 }
 
-let distTwo = (
+let twoDistsOrNumbers = (
   ~fn: (float, float) => result<DistributionTypes.genericDist, string>,
-  a1: value,
-  a2: value,
+  ~values: (distOrNumber, distOrNumber),
 ) => {
   let toSampleSet = r => GenericDist.toSampleSetDist(r, 1000)
   let sampleSetToExpressionValue = (
@@ -299,12 +311,11 @@ let distTwo = (
     sampleSetResult->sampleSetToExpressionValue
   }
 
-  switch (a1, a2) {
-  | (DistOrNumber(Number(a1)), DistOrNumber(Number(a2))) =>
-    fn(a1, a2)->E.R2.fmap(r => ReducerInterface_ExpressionValue.EvDistribution(r))
-  | (DistOrNumber(Dist(a1)), DistOrNumber(Number(a2))) => singleVarSample(a1, r => fn(r, a2))
-  | (DistOrNumber(Number(a1)), DistOrNumber(Dist(a2))) => singleVarSample(a2, r => fn(a1, r))
-  | (DistOrNumber(Dist(a1)), DistOrNumber(Dist(a2))) => {
+  switch values {
+  | (Number(a1), Number(a2)) => fn(a1, a2)->E.R2.fmap(Wrappers.evDistribution)
+  | (Dist(a1), Number(a2)) => singleVarSample(a1, r => fn(r, a2))
+  | (Number(a1), Dist(a2)) => singleVarSample(a2, r => fn(a1, r))
+  | (Dist(a1), Dist(a2)) => {
       let altFn = (a, b) => fn(a, b)->mapFnResult
       let sampleSetResult =
         E.R.merge(toSampleSet(a1), toSampleSet(a2))
@@ -315,57 +326,87 @@ let distTwo = (
         ->E.R2.errMap(r => DistributionTypes.OtherError(r))
       sampleSetResult->sampleSetToExpressionValue
     }
-  | _ => Error(impossibleError)
   }
 }
 
-let normal = Function.make(
-  "Normal",
-  [
-    Function.makeDefinition("normal", [I_DistOrNumber, I_DistOrNumber], inputs => {
-      let combine = (a1: float, a2: float) =>
-        SymbolicDist.Normal.make(a1, a2)->E.R2.fmap(r => DistributionTypes.Symbolic(r))
-      distTwo(~fn=combine, inputs[0], inputs[1])
-    }),
-    Function.makeDefinition(
-      "normal",
-      [I_Record([("mean", I_Numeric), ("stdev", I_Numeric)])],
-      inputs =>
-        twoNumberInputsRecord("mean", "stdev", inputs)->E.R.bind(((mean, stdev)) =>
-          meanStdev(mean, stdev)
-        ),
-    ),
-    Function.makeDefinition("normal", [I_Record([("p5", I_Numeric), ("p95", I_Numeric)])], inputs =>
-      twoNumberInputsRecord("p5", "p95", inputs)->E.R.bind(((v1, v2)) => Ok(p5and95(v1, v2)))
-    ),
-  ],
-)
+module NormalFn = {
+  let fnName = "normal"
+  let twoFloatsToSymoblic = (a1: float, a2: float) =>
+    SymbolicDist.Normal.make(a1, a2)->E.R2.fmap(Wrappers.symbolic)
+  let twoFloatsToSymbolic90P = (a1: float, a2: float) =>
+    SymbolicDist.Normal.from90PercentCI(a1, a2)->Wrappers.symbolic->Ok
 
-let logNormal = Function.make(
-  "Lognormal",
-  [
-    Function.makeDefinition("lognormal", [I_Numeric, I_Numeric], inputs =>
-      twoNumberInputs(inputs)->E.R.bind(((mu, sigma)) =>
-        SymbolicDist.Lognormal.make(mu, sigma)->E.R2.fmap(contain)
-      )
-    ),
-    Function.makeDefinition(
-      "lognormal",
-      [I_Record([("p5", I_Numeric), ("p95", I_Numeric)])],
-      inputs =>
-        twoNumberInputsRecord("p5", "p95", inputs)->E.R.bind(((p5, p95)) => Ok(
-          contain(SymbolicDist.Lognormal.from90PercentCI(p5, p95)),
-        )),
-    ),
-    Function.makeDefinition(
-      "lognormal",
-      [I_Record([("mean", I_Numeric), ("stdev", I_Numeric)])],
-      inputs =>
-        twoNumberInputsRecord("mean", "stdev", inputs)->E.R.bind(((mean, stdev)) =>
-          SymbolicDist.Lognormal.fromMeanAndStdev(mean, stdev)->E.R2.fmap(contain)
-        ),
-    ),
-  ],
-)
+  let toFn = Function.make(
+    ~name="Normal",
+    ~definitions=[
+      Function.makeDefinition(
+        ~name=fnName,
+        ~inputs=[I_DistOrNumber, I_DistOrNumber],
+        ~run=inputs => {
+          inputs
+          ->Prepare.twoDistOrNumber
+          ->E.R.bind(twoDistsOrNumbers(~fn=twoFloatsToSymoblic, ~values=_))
+        },
+      ),
+      Function.makeDefinition(
+        ~name=fnName,
+        ~inputs=[I_Record([("mean", I_DistOrNumber), ("stdev", I_DistOrNumber)])],
+        ~run=inputs =>
+          inputs
+          ->Prepare.twoNumberInputsRecord3
+          ->E.R.bind(Prepare.twoDistOrNumber)
+          ->E.R.bind(twoDistsOrNumbers(~fn=twoFloatsToSymoblic, ~values=_)),
+      ),
+      Function.makeDefinition(
+        ~name=fnName,
+        ~inputs=[I_Record([("p5", I_DistOrNumber), ("p95", I_DistOrNumber)])],
+        ~run=inputs =>
+          inputs
+          ->Prepare.twoNumberInputsRecord3
+          ->E.R.bind(Prepare.twoDistOrNumber)
+          ->E.R.bind(twoDistsOrNumbers(~fn=twoFloatsToSymbolic90P, ~values=_)),
+      ),
+    ],
+  )
+}
 
-let allFunctions = [normal, logNormal]
+module LognormalFn = {
+  let fnName = "lognormal"
+  let twoFloatsToSymoblic = (a1, a2) =>
+    SymbolicDist.Lognormal.make(a1, a2)->E.R2.fmap(Wrappers.symbolic)
+  let twoFloatsToSymbolic90P = (a1, a2) =>
+    SymbolicDist.Lognormal.from90PercentCI(a1, a2)->Wrappers.symbolic->Ok
+  let twoFloatsToMeanStdev = (a1, a2) =>
+    SymbolicDist.Lognormal.fromMeanAndStdev(a1, a2)->E.R2.fmap(Wrappers.symbolic)
+
+  let toFn = Function.make(
+    ~name="Lognormal",
+    ~definitions=[
+      Function.makeDefinition(~name=fnName, ~inputs=[I_DistOrNumber, I_DistOrNumber], ~run=inputs =>
+        inputs
+        ->Prepare.twoDistOrNumber
+        ->E.R.bind(twoDistsOrNumbers(~fn=twoFloatsToSymoblic, ~values=_))
+      ),
+      Function.makeDefinition(
+        ~name=fnName,
+        ~inputs=[I_Record([("p5", I_DistOrNumber), ("p95", I_DistOrNumber)])],
+        ~run=inputs =>
+          inputs
+          ->Prepare.twoNumberInputsRecord3
+          ->E.R.bind(Prepare.twoDistOrNumber)
+          ->E.R.bind(twoDistsOrNumbers(~fn=twoFloatsToSymbolic90P, ~values=_)),
+      ),
+      Function.makeDefinition(
+        ~name=fnName,
+        ~inputs=[I_Record([("mean", I_DistOrNumber), ("stdev", I_DistOrNumber)])],
+        ~run=inputs =>
+          inputs
+          ->Prepare.twoNumberInputsRecord3
+          ->E.R.bind(Prepare.twoDistOrNumber)
+          ->E.R.bind(twoDistsOrNumbers(~fn=twoFloatsToMeanStdev, ~values=_)),
+      ),
+    ],
+  )
+}
+
+let allFunctions = [NormalFn.toFn, LognormalFn.toFn]