Merged with develop

.prettierignore

@@ -11,3 +11,4 @@ packages/squiggle-lang/.nyc_output/
 packages/squiggle-lang/coverage/
 packages/squiggle-lang/.cache/
 packages/website/build/
+packages/squiggle-lang/src/rescript/Reducer/Reducer_Peggy/Reducer_Peggy_GeneratedParser.js

packages/components/package.json

@@ -19,13 +19,13 @@
   "devDependencies": {
     "@babel/plugin-proposal-private-property-in-object": "^7.17.12",
     "@storybook/addon-actions": "^6.5.3",
-    "@storybook/addon-essentials": "^6.5.3",
-    "@storybook/addon-links": "^6.5.3",
-    "@storybook/builder-webpack5": "^6.5.3",
-    "@storybook/manager-webpack5": "^6.5.3",
-    "@storybook/node-logger": "^6.4.22",
-    "@storybook/preset-create-react-app": "^4.1.0",
-    "@storybook/react": "^6.5.3",
+    "@storybook/addon-essentials": "^6.5.4",
+    "@storybook/addon-links": "^6.5.4",
+    "@storybook/builder-webpack5": "^6.5.4",
+    "@storybook/manager-webpack5": "^6.5.4",
+    "@storybook/node-logger": "^6.5.4",
+    "@storybook/preset-create-react-app": "^4.1.1",
+    "@storybook/react": "^6.5.4",
     "@testing-library/jest-dom": "^5.16.4",
     "@testing-library/react": "^13.2.0",
     "@testing-library/user-event": "^14.2.0",

packages/squiggle-lang/.gitignore

@@ -21,3 +21,4 @@ dist
 _coverage
 coverage
 .nyc_output/
+src/rescript/Reducer/Reducer_Peggy/Reducer_Peggy_GeneratedParser.js

packages/squiggle-lang/.prettierignore

@@ -4,4 +4,5 @@ lib
 *.gen.tsx
 .nyc_output/
 coverage/
-.cache/
+.cache/
+Reducer_Peggy_GeneratedParser.js

packages/squiggle-lang/__tests__/ReducerInterface/ReducerInterface_Distribution_test.res

@@ -23,7 +23,7 @@ describe("eval on distribution functions", () => {
     testEval("-normal(5,2)", "Ok(Normal(-5,2))")
   })
   describe("to", () => {
-    testEval("5 to 2", "Error(Distribution Math Error: Low value must be less than high value.)")
+    testEval("5 to 2", "Error(TODO: Low value must be less than high value.)")
     testEval("to(2,5)", "Ok(Lognormal(1.1512925464970227,0.27853260523016377))")
     testEval("to(-2,2)", "Ok(Normal(0,1.2159136638235384))")
   })

packages/squiggle-lang/package.json

@@ -4,9 +4,9 @@
   "homepage": "https://squiggle-language.com",
   "license": "MIT",
   "scripts": {
-    "peggy": "peggy --cache ",
-    "build:peggy": "find . -type f -name *.peggy -exec yarn run peggy {} \\;",
-    "build": "yarn build:rescript && yarn build:typescript",
+    "peggy": "peggy --cache",
+    "build": "yarn build:peggy && yarn build:rescript && yarn build:typescript",
+    "build:peggy": "find . -type f -name *.peggy -exec yarn peggy {} \\;",
     "build:rescript": "rescript build -with-deps",
     "build:typescript": "tsc",
     "bundle": "webpack",
@@ -61,7 +61,7 @@
     "rescript-fast-check": "^1.1.1",
     "ts-jest": "^27.1.4",
     "ts-loader": "^9.3.0",
-    "ts-node": "^10.7.0",
+    "ts-node": "^10.8.0",
     "typescript": "^4.6.3",
     "webpack": "^5.72.1",
     "webpack-cli": "^4.9.2"

packages/squiggle-lang/src/rescript/Distributions/GenericDist.res

@@ -31,6 +31,8 @@ let sampleN = (t: t, n) =>
   | SampleSet(r) => SampleSetDist.sampleN(r, n)
   }
 
+let sample = (t: t) => sampleN(t, 1)->E.A.first |> E.O.toExn("Should not have happened")
+
 let toSampleSetDist = (t: t, n) =>
   SampleSetDist.make(sampleN(t, n))->E.R2.errMap(DistributionTypes.Error.sampleErrorToDistErr)
 

packages/squiggle-lang/src/rescript/Distributions/GenericDist.resi

@@ -6,6 +6,7 @@ type scaleMultiplyFn = (t, float) => result<t, error>
 type pointwiseAddFn = (t, t) => result<t, error>
 
 let sampleN: (t, int) => array<float>
+let sample: t => float
 
 let toSampleSetDist: (t, int) => Belt.Result.t<QuriSquiggleLang.SampleSetDist.t, error>
 

packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res

@@ -0,0 +1,301 @@
+type expressionValue = ReducerInterface_ExpressionValue.expressionValue
+
+/*
+  Function Registry "Type". A type, without any other information.
+  Like, #Float
+*/
+type rec frType =
+  | FRTypeNumber
+  | FRTypeNumeric
+  | FRTypeDistOrNumber
+  | FRTypeRecord(frTypeRecord)
+  | FRTypeArray(array<frType>)
+  | FRTypeOption(frType)
+and frTypeRecord = array<frTypeRecordParam>
+and frTypeRecordParam = (string, frType)
+
+/*
+  Function Registry "Value". A type, with the information of that type.
+  Like, #Float(40.0)
+*/
+type rec frValue =
+  | FRValueNumber(float)
+  | FRValueDist(DistributionTypes.genericDist)
+  | FRValueOption(option<frValue>)
+  | FRValueDistOrNumber(frValueDistOrNumber)
+  | FRValueRecord(frValueRecord)
+and frValueRecord = array<frValueRecordParam>
+and frValueRecordParam = (string, frValue)
+and frValueDistOrNumber = FRValueNumber(float) | FRValueDist(DistributionTypes.genericDist)
+
+type fnDefinition = {
+  name: string,
+  inputs: array<frType>,
+  run: (array<frValue>, DistributionOperation.env) => result<expressionValue, string>,
+}
+
+type function = {
+  name: string,
+  definitions: array<fnDefinition>,
+}
+
+type registry = array<function>
+
+module FRType = {
+  type t = frType
+  let rec toString = (t: t) =>
+    switch t {
+    | FRTypeNumber => "number"
+    | FRTypeNumeric => "numeric"
+    | FRTypeDistOrNumber => "frValueDistOrNumber"
+    | FRTypeRecord(r) => {
+        let input = ((name, frType): frTypeRecordParam) => `${name}: ${toString(frType)}`
+        `record({${r->E.A2.fmap(input)->E.A2.joinWith(", ")}})`
+      }
+    | FRTypeArray(r) => `record(${r->E.A2.fmap(toString)->E.A2.joinWith(", ")})`
+    | FRTypeOption(v) => `option(${toString(v)})`
+    }
+
+  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)))) =>
+      Some(FRValueDistOrNumber(FRValueNumber(f)))
+    | (FRTypeDistOrNumber, EvDistribution(f)) => Some(FRValueDistOrNumber(FRValueDist(f)))
+    | (FRTypeNumeric, EvNumber(f)) => Some(FRValueNumber(f))
+    | (FRTypeNumeric, EvDistribution(Symbolic(#Float(f)))) => Some(FRValueNumber(f))
+    | (FRTypeOption(v), _) => Some(FRValueOption(matchWithExpressionValue(v, r)))
+    | (FRTypeRecord(recordParams), EvRecord(record)) => {
+        let getAndMatch = (name, input) =>
+          E.Dict.get(record, name)->E.O.bind(matchWithExpressionValue(input))
+        //All names in the type must be present. If any are missing, the corresponding
+        //value will be None, and this function would return None.
+        let namesAndValues: array<option<(Js.Dict.key, frValue)>> =
+          recordParams->E.A2.fmap(((name, input)) =>
+            getAndMatch(name, input)->E.O2.fmap(match => (name, match))
+          )
+        namesAndValues->E.A.O.openIfAllSome->E.O2.fmap(r => FRValueRecord(r))
+      }
+    | _ => None
+    }
+
+  let matchWithExpressionValueArray = (inputs: array<t>, args: array<expressionValue>): option<
+    array<frValue>,
+  > => {
+    let isSameLength = E.A.length(inputs) == E.A.length(args)
+    if !isSameLength {
+      None
+    } else {
+      E.A.zip(inputs, args)
+      ->E.A2.fmap(((input, arg)) => matchWithExpressionValue(input, arg))
+      ->E.A.O.openIfAllSome
+    }
+  }
+}
+
+/*
+  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
+
+    let isFullMatch = (match: t) =>
+      switch match {
+      | FullMatch => true
+      | _ => false
+      }
+
+    let isNameMatchOnly = (match: t) =>
+      switch match {
+      | SameNameDifferentArguments => true
+      | _ => false
+      }
+  }
+
+  module Match = {
+    type t<'a, 'b> = DifferentName | SameNameDifferentArguments('a) | FullMatch('b)
+
+    let isFullMatch = (match: t<'a, 'b>): bool =>
+      switch match {
+      | FullMatch(_) => true
+      | _ => false
+      }
+
+    let isNameMatchOnly = (match: t<'a, 'b>) =>
+      switch match {
+      | SameNameDifferentArguments(_) => true
+      | _ => false
+      }
+  }
+
+  module FnDefinition = {
+    let matchAssumingSameName = (f: fnDefinition, args: array<expressionValue>) => {
+      switch FRType.matchWithExpressionValueArray(f.inputs, args) {
+      | Some(_) => MatchSimple.FullMatch
+      | None => MatchSimple.SameNameDifferentArguments
+      }
+    }
+
+    let match = (f: fnDefinition, fnName: string, args: array<expressionValue>) => {
+      if f.name !== fnName {
+        MatchSimple.DifferentName
+      } else {
+        matchAssumingSameName(f, args)
+      }
+    }
+  }
+
+  module Function = {
+    type definitionId = int
+    type match = Match.t<array<definitionId>, definitionId>
+
+    let match = (f: function, fnName: string, args: array<expressionValue>): match => {
+      let matchedDefinition = () =>
+        E.A.getIndexBy(f.definitions, r =>
+          MatchSimple.isFullMatch(FnDefinition.match(r, fnName, args))
+        ) |> E.O.fmap(r => Match.FullMatch(r))
+      let getMatchedNameOnlyDefinition = () => {
+        let nameMatchIndexes =
+          f.definitions
+          ->E.A2.fmapi((index, r) =>
+            MatchSimple.isNameMatchOnly(FnDefinition.match(r, fnName, args)) ? Some(index) : None
+          )
+          ->E.A.O.concatSomes
+        switch nameMatchIndexes {
+        | [] => None
+        | elements => Some(Match.SameNameDifferentArguments(elements))
+        }
+      }
+
+      E.A.O.firstSomeFnWithDefault(
+        [matchedDefinition, getMatchedNameOnlyDefinition],
+        Match.DifferentName,
+      )
+    }
+  }
+
+  module RegistryMatch = {
+    type match = {
+      fnName: string,
+      inputIndex: int,
+    }
+    let makeMatch = (fnName: string, inputIndex: int) => {fnName: fnName, inputIndex: inputIndex}
+  }
+
+  module Registry = {
+    let _findExactMatches = (r: registry, fnName: string, args: array<expressionValue>) => {
+      let functionMatchPairs = r->E.A2.fmap(l => (l, Function.match(l, fnName, args)))
+      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
+        }
+      )
+    }
+
+    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
+        ->E.A2.fmap(((fn, match)) => Match.isNameMatchOnly(match) ? Some((fn, match)) : None)
+        ->E.A.O.concatSomes
+      let matches =
+        getNameMatches
+        ->E.A2.fmap(((fn, match)) =>
+          switch match {
+          | SameNameDifferentArguments(indexes) =>
+            indexes->E.A2.fmap(index => RegistryMatch.makeMatch(fn.name, index))
+          | _ => []
+          }
+        )
+        ->Belt.Array.concatMany
+      E.A.toNoneIfEmpty(matches)
+    }
+
+    let findMatches = (r: registry, fnName: string, args: array<expressionValue>) => {
+      switch _findExactMatches(r, fnName, args) {
+      | Some(r) => Match.FullMatch(r)
+      | None =>
+        switch _findNameMatches(r, fnName, args) {
+        | Some(r) => Match.SameNameDifferentArguments(r)
+        | None => Match.DifferentName
+        }
+      }
+    }
+
+    let matchToDef = (registry: registry, {fnName, inputIndex}: RegistryMatch.match): option<
+      fnDefinition,
+    > =>
+      registry
+      ->E.A.getBy(fn => fn.name === fnName)
+      ->E.O.bind(fn => E.A.get(fn.definitions, inputIndex))
+  }
+}
+
+module FnDefinition = {
+  type t = fnDefinition
+
+  let toString = (t: t) => {
+    let inputs = t.inputs->E.A2.fmap(FRType.toString)->E.A2.joinWith(", ")
+    t.name ++ `(${inputs})`
+  }
+
+  let run = (t: t, args: array<expressionValue>, env: DistributionOperation.env) => {
+    let argValues = FRType.matchWithExpressionValueArray(t.inputs, args)
+    switch argValues {
+    | Some(values) => t.run(values, env)
+    | None => Error("Incorrect Types")
+    }
+  }
+
+  let make = (~name, ~inputs, ~run): t => {
+    name: name,
+    inputs: inputs,
+    run: run,
+  }
+}
+
+module Function = {
+  type t = function
+
+  let make = (~name, ~definitions): t => {
+    name: name,
+    definitions: definitions,
+  }
+}
+
+module Registry = {
+  /*
+  There's a (potential+minor) bug here: If a function definition is called outside of the calls 
+  to the registry, then it's possible that there could be a match after the registry is 
+  called. However, for now, we could just call the registry last.
+ */
+  let matchAndRun = (
+    ~registry: registry,
+    ~fnName: string,
+    ~args: array<expressionValue>,
+    ~env: DistributionOperation.env,
+  ) => {
+    let matchToDef = m => Matcher.Registry.matchToDef(registry, m)
+    let showNameMatchDefinitions = matches => {
+      let defs =
+        matches
+        ->E.A2.fmap(matchToDef)
+        ->E.A.O.concatSomes
+        ->E.A2.fmap(FnDefinition.toString)
+        ->E.A2.fmap(r => `[${r}]`)
+        ->E.A2.joinWith("; ")
+      `There are function matches for ${fnName}(), but with different arguments: ${defs}`
+    }
+    switch Matcher.Registry.findMatches(registry, fnName, args) {
+    | Matcher.Match.FullMatch(match) => match->matchToDef->E.O2.fmap(FnDefinition.run(_, args, env))
+    | SameNameDifferentArguments(m) => Some(Error(showNameMatchDefinitions(m)))
+    | _ => None
+    }
+  }
+}

packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.resi

@@ -0,0 +1,58 @@
+type expressionValue = ReducerInterface_ExpressionValue.expressionValue
+
+type rec frType =
+  | FRTypeNumber
+  | FRTypeNumeric
+  | FRTypeDistOrNumber
+  | FRTypeRecord(frTypeRecord)
+  | FRTypeArray(array<frType>)
+  | FRTypeOption(frType)
+and frTypeRecord = array<frTypeRecordParam>
+and frTypeRecordParam = (string, frType)
+
+type rec frValue =
+  | FRValueNumber(float)
+  | FRValueDist(DistributionTypes.genericDist)
+  | FRValueOption(option<frValue>)
+  | FRValueDistOrNumber(frValueDistOrNumber)
+  | FRValueRecord(frValueRecord)
+and frValueRecord = array<frValueRecordParam>
+and frValueRecordParam = (string, frValue)
+and frValueDistOrNumber = FRValueNumber(float) | FRValueDist(DistributionTypes.genericDist)
+
+type fnDefinition = {
+  name: string,
+  inputs: array<frType>,
+  run: (array<frValue>, DistributionOperation.env) => result<expressionValue, string>,
+}
+
+type function = {
+  name: string,
+  definitions: array<fnDefinition>,
+}
+
+type registry = array<function>
+
+// Note: The function "name" is just used for documentation purposes
+module Function: {
+  type t = function
+  let make: (~name: string, ~definitions: array<fnDefinition>) => t
+}
+
+module FnDefinition: {
+  type t = fnDefinition
+  let make: (
+    ~name: string,
+    ~inputs: array<frType>,
+    ~run: (array<frValue>, DistributionOperation.env) => result<expressionValue, string>,
+  ) => t
+}
+
+module Registry: {
+  let matchAndRun: (
+    ~registry: registry,
+    ~fnName: string,
+    ~args: array<expressionValue>,
+    ~env: QuriSquiggleLang.DistributionOperation.env,
+  ) => option<result<expressionValue, string>>
+}

packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Helpers.res

@@ -0,0 +1,156 @@
+open FunctionRegistry_Core
+
+let impossibleError = "Wrong inputs / Logically impossible"
+
+module Wrappers = {
+  let symbolic = r => DistributionTypes.Symbolic(r)
+  let evDistribution = r => ReducerInterface_ExpressionValue.EvDistribution(r)
+  let symbolicEvDistribution = r => r->DistributionTypes.Symbolic->evDistribution
+}
+
+module Prepare = {
+  type ts = array<frValue>
+  type err = string
+
+  module ToValueArray = {
+    module Record = {
+      let twoArgs = (inputs: ts): result<ts, err> =>
+        switch inputs {
+        | [FRValueRecord([(_, n1), (_, n2)])] => Ok([n1, n2])
+        | _ => Error(impossibleError)
+        }
+    }
+  }
+
+  module ToValueTuple = {
+    let twoDistOrNumber = (values: ts): result<(frValueDistOrNumber, frValueDistOrNumber), err> => {
+      switch values {
+      | [FRValueDistOrNumber(a1), FRValueDistOrNumber(a2)] => Ok(a1, a2)
+      | _ => Error(impossibleError)
+      }
+    }
+
+    let oneDistOrNumber = (values: ts): result<frValueDistOrNumber, err> => {
+      switch values {
+      | [FRValueDistOrNumber(a1)] => Ok(a1)
+      | _ => Error(impossibleError)
+      }
+    }
+
+    module Record = {
+      let twoDistOrNumber = (values: ts): result<(frValueDistOrNumber, frValueDistOrNumber), err> =>
+        values->ToValueArray.Record.twoArgs->E.R.bind(twoDistOrNumber)
+    }
+  }
+}
+
+module Process = {
+  module DistOrNumberToDist = {
+    module Helpers = {
+      let toSampleSet = (r, env: DistributionOperation.env) =>
+        GenericDist.toSampleSetDist(r, env.sampleCount)
+
+      let mapFnResult = r =>
+        switch r {
+        | Ok(r) => Ok(GenericDist.sample(r))
+        | Error(r) => Error(Operation.Other(r))
+        }
+
+      let wrapSymbolic = (fn, r) => r->fn->E.R2.fmap(Wrappers.symbolic)
+
+      let singleVarSample = (dist, fn, env) => {
+        switch toSampleSet(dist, env) {
+        | Ok(dist) =>
+          switch SampleSetDist.samplesMap(~fn=f => fn(f)->mapFnResult, dist) {
+          | Ok(r) => Ok(DistributionTypes.SampleSet(r))
+          | Error(r) => Error(DistributionTypes.Error.toString(DistributionTypes.SampleSetError(r)))
+          }
+        | Error(r) => Error(DistributionTypes.Error.toString(r))
+        }
+      }
+
+      let twoVarSample = (dist1, dist2, fn, env) => {
+        let altFn = (a, b) => fn((a, b))->mapFnResult
+        switch E.R.merge(toSampleSet(dist1, env), toSampleSet(dist2, env)) {
+        | Ok((t1, t2)) =>
+          switch SampleSetDist.map2(~fn=altFn, ~t1, ~t2) {
+          | Ok(r) => Ok(DistributionTypes.SampleSet(r))
+          | Error(r) => Error(Operation.Error.toString(r))
+          }
+        | Error(r) => Error(DistributionTypes.Error.toString(r))
+        }
+      }
+    }
+
+    let oneValue = (
+      ~fn: float => result<DistributionTypes.genericDist, string>,
+      ~value: frValueDistOrNumber,
+      ~env: DistributionOperation.env,
+    ): result<DistributionTypes.genericDist, string> => {
+      switch value {
+      | FRValueNumber(a1) => fn(a1)
+      | FRValueDist(a1) => Helpers.singleVarSample(a1, r => fn(r), env)
+      }
+    }
+
+    let oneValueUsingSymbolicDist = (~fn, ~value) => oneValue(~fn=Helpers.wrapSymbolic(fn), ~value)
+
+    let twoValues = (
+      ~fn: ((float, float)) => result<DistributionTypes.genericDist, string>,
+      ~values: (frValueDistOrNumber, frValueDistOrNumber),
+      ~env: DistributionOperation.env,
+    ): result<DistributionTypes.genericDist, string> => {
+      switch values {
+      | (FRValueNumber(a1), FRValueNumber(a2)) => fn((a1, a2))
+      | (FRValueDist(a1), FRValueNumber(a2)) => Helpers.singleVarSample(a1, r => fn((r, a2)), env)
+      | (FRValueNumber(a1), FRValueDist(a2)) => Helpers.singleVarSample(a2, r => fn((a1, r)), env)
+      | (FRValueDist(a1), FRValueDist(a2)) => Helpers.twoVarSample(a1, a2, fn, env)
+      }
+    }
+
+    let twoValuesUsingSymbolicDist = (~fn, ~values) =>
+      twoValues(~fn=Helpers.wrapSymbolic(fn), ~values)
+  }
+}
+
+module TwoArgDist = {
+  let process = (~fn, ~env, r) =>
+    r
+    ->E.R.bind(Process.DistOrNumberToDist.twoValuesUsingSymbolicDist(~fn, ~values=_, ~env))
+    ->E.R2.fmap(Wrappers.evDistribution)
+
+  let make = (name, fn) => {
+    FnDefinition.make(~name, ~inputs=[FRTypeDistOrNumber, FRTypeDistOrNumber], ~run=(inputs, env) =>
+      inputs->Prepare.ToValueTuple.twoDistOrNumber->process(~fn, ~env)
+    )
+  }
+
+  let makeRecordP5P95 = (name, fn) => {
+    FnDefinition.make(
+      ~name,
+      ~inputs=[FRTypeRecord([("p5", FRTypeDistOrNumber), ("p95", FRTypeDistOrNumber)])],
+      ~run=(inputs, env) => inputs->Prepare.ToValueTuple.Record.twoDistOrNumber->process(~fn, ~env),
+    )
+  }
+
+  let makeRecordMeanStdev = (name, fn) => {
+    FnDefinition.make(
+      ~name,
+      ~inputs=[FRTypeRecord([("mean", FRTypeDistOrNumber), ("stdev", FRTypeDistOrNumber)])],
+      ~run=(inputs, env) => inputs->Prepare.ToValueTuple.Record.twoDistOrNumber->process(~fn, ~env),
+    )
+  }
+}
+
+module OneArgDist = {
+  let process = (~fn, ~env, r) =>
+    r
+    ->E.R.bind(Process.DistOrNumberToDist.oneValueUsingSymbolicDist(~fn, ~value=_, ~env))
+    ->E.R2.fmap(Wrappers.evDistribution)
+
+  let make = (name, fn) => {
+    FnDefinition.make(~name, ~inputs=[FRTypeDistOrNumber], ~run=(inputs, env) =>
+      inputs->Prepare.ToValueTuple.oneDistOrNumber->process(~fn, ~env)
+    )
+  }
+}

packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res

@@ -0,0 +1,65 @@
+open FunctionRegistry_Core
+open FunctionRegistry_Helpers
+
+let twoArgs = E.Tuple2.toFnCall
+
+let registry = [
+  Function.make(
+    ~name="Normal",
+    ~definitions=[
+      TwoArgDist.make("normal", twoArgs(SymbolicDist.Normal.make)),
+      TwoArgDist.makeRecordP5P95("normal", r =>
+        twoArgs(SymbolicDist.Normal.from90PercentCI, r)->Ok
+      ),
+      TwoArgDist.makeRecordMeanStdev("normal", twoArgs(SymbolicDist.Normal.make)),
+    ],
+  ),
+  Function.make(
+    ~name="Lognormal",
+    ~definitions=[
+      TwoArgDist.make("lognormal", twoArgs(SymbolicDist.Lognormal.make)),
+      TwoArgDist.makeRecordP5P95("lognormal", r =>
+        twoArgs(SymbolicDist.Lognormal.from90PercentCI, r)->Ok
+      ),
+      TwoArgDist.makeRecordMeanStdev("lognormal", twoArgs(SymbolicDist.Lognormal.fromMeanAndStdev)),
+    ],
+  ),
+  Function.make(
+    ~name="Uniform",
+    ~definitions=[TwoArgDist.make("uniform", twoArgs(SymbolicDist.Uniform.make))],
+  ),
+  Function.make(
+    ~name="Beta",
+    ~definitions=[TwoArgDist.make("beta", twoArgs(SymbolicDist.Beta.make))],
+  ),
+  Function.make(
+    ~name="Cauchy",
+    ~definitions=[TwoArgDist.make("cauchy", twoArgs(SymbolicDist.Cauchy.make))],
+  ),
+  Function.make(
+    ~name="Gamma",
+    ~definitions=[TwoArgDist.make("gamma", twoArgs(SymbolicDist.Gamma.make))],
+  ),
+  Function.make(
+    ~name="Logistic",
+    ~definitions=[TwoArgDist.make("logistic", twoArgs(SymbolicDist.Logistic.make))],
+  ),
+  Function.make(
+    ~name="To",
+    ~definitions=[
+      TwoArgDist.make("to", twoArgs(SymbolicDist.From90thPercentile.make)),
+      TwoArgDist.make(
+        "credibleIntervalToDistribution",
+        twoArgs(SymbolicDist.From90thPercentile.make),
+      ),
+    ],
+  ),
+  Function.make(
+    ~name="Exponential",
+    ~definitions=[OneArgDist.make("exponential", SymbolicDist.Exponential.make)],
+  ),
+  Function.make(
+    ~name="Bernoulli",
+    ~definitions=[OneArgDist.make("bernoulli", SymbolicDist.Bernoulli.make)],
+  ),
+]

packages/squiggle-lang/src/rescript/FunctionRegistry/README.md

@@ -0,0 +1,46 @@
+# Function Registry
+
+The function registry is a library for organizing function definitions.
+
+The main interface is fairly constrained. Basically, write functions like the following, and add them to a big array.
+
+```rescript
+  Function.make(
+    ~name="Normal",
+    ~definitions=[
+        FnDefinition.make(
+            ~name="Normal",
+            ~definitions=[
+                FnDefinition.make(~name="normal", ~inputs=[FRTypeDistOrNumber, FRTypeDistOrNumber], ~run=(
+                    inputs,
+                    env,
+                ) =>
+                    inputs
+                    ->Prepare.ToValueTuple.twoDistOrNumber
+                    ->E.R.bind(
+                    Process.twoDistsOrNumbersToDistUsingSymbolicDist(
+                        ~fn=E.Tuple2.toFnCall(SymbolicDist.Normal.make),
+                        ~env,
+                        ~values=_,
+                    ),
+                    )
+                    ->E.R2.fmap(Wrappers.evDistribution)
+                ),
+            ],
+        )
+    ],
+  )
+```
+
+The Function name is just there for future documentation. The function defintions
+
+## Key Files
+
+**FunctionRegistry_Core**
+Key types, internal functionality, and a `Registry` module with a `matchAndRun` function to call function definitions.
+
+**FunctionRegistry_Library**
+A list of all the Functions defined in the Function Registry.
+
+**FunctionRegistry_Helpers**
+A list of helper functions for the FunctionRegistry_Library.

packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_GenericDistribution.res

@@ -179,27 +179,6 @@ module Helpers = {
 }
 
 module SymbolicConstructors = {
-  let oneFloat = name =>
-    switch name {
-    | "exponential" => Ok(SymbolicDist.Exponential.make)
-    | "bernoulli" => Ok(SymbolicDist.Bernoulli.make)
-    | _ => Error("Unreachable state")
-    }
-
-  let twoFloat = name =>
-    switch name {
-    | "beta" => Ok(SymbolicDist.Beta.make)
-    | "cauchy" => Ok(SymbolicDist.Cauchy.make)
-    | "credibleIntervalToDistribution" => Ok(SymbolicDist.From90thPercentile.make)
-    | "gamma" => Ok(SymbolicDist.Gamma.make)
-    | "logistic" => Ok(SymbolicDist.Logistic.make)
-    | "lognormal" => Ok(SymbolicDist.Lognormal.make)
-    | "normal" => Ok(SymbolicDist.Normal.make)
-    | "to" => Ok(SymbolicDist.From90thPercentile.make) // as credibleIntervalToDistribution is defined "to" might be redundant
-    | "uniform" => Ok(SymbolicDist.Uniform.make)
-    | _ => Error("Unreachable state")
-    }
-
   let threeFloat = name =>
     switch name {
     | "triangular" => Ok(SymbolicDist.Triangular.make)
@@ -221,27 +200,8 @@ let dispatchToGenericOutput = (
 ): option<DistributionOperation.outputType> => {
   let (fnName, args) = call
   switch (fnName, args) {
-  | (("exponential" | "bernoulli") as fnName, [EvNumber(f)]) =>
-    SymbolicConstructors.oneFloat(fnName)
-    ->E.R.bind(r => r(f))
-    ->SymbolicConstructors.symbolicResultToOutput
   | ("delta", [EvNumber(f)]) =>
     SymbolicDist.Float.makeSafe(f)->SymbolicConstructors.symbolicResultToOutput
-  | (
-      ("normal"
-      | "uniform"
-      | "beta"
-      | "lognormal"
-      | "cauchy"
-      | "gamma"
-      | "credibleIntervalToDistribution"
-      | "to"
-      | "logistic") as fnName,
-      [EvNumber(f1), EvNumber(f2)],
-    ) =>
-    SymbolicConstructors.twoFloat(fnName)
-    ->E.R.bind(r => r(f1, f2))
-    ->SymbolicConstructors.symbolicResultToOutput
   | ("triangular" as fnName, [EvNumber(f1), EvNumber(f2), EvNumber(f3)]) =>
     SymbolicConstructors.threeFloat(fnName)
     ->E.R.bind(r => r(f1, f2, f3))
@@ -390,6 +350,20 @@ let genericOutputToReducerValue = (o: DistributionOperation.outputType): result<
   | GenDistError(err) => Error(REDistributionError(err))
   }
 
-let dispatch = (call, environment) => {
-  dispatchToGenericOutput(call, environment)->E.O2.fmap(genericOutputToReducerValue)
+// I expect that it's important to build this first, so it doesn't get recalculated for each tryRegistry() call.
+let registry = FunctionRegistry_Library.registry
+
+let tryRegistry = ((fnName, args): ExpressionValue.functionCall, env) => {
+  FunctionRegistry_Core.Registry.matchAndRun(~registry, ~fnName, ~args, ~env)->E.O2.fmap(
+    E.R2.errMap(_, s => Reducer_ErrorValue.RETodo(s)),
+  )
+}
+
+let dispatch = (call: ExpressionValue.functionCall, environment) => {
+  let regularDispatch =
+    dispatchToGenericOutput(call, environment)->E.O2.fmap(genericOutputToReducerValue)
+  switch regularDispatch {
+  | Some(x) => Some(x)
+  | None => tryRegistry(call, environment)
+  }
 }

packages/squiggle-lang/src/rescript/Utility/E.res

@@ -2,6 +2,9 @@
 Some functions from modules `L`, `O`, and `R` below were copied directly from
 running `rescript convert -all` on Rationale https://github.com/jonlaing/rationale
 */
+
+let equals = (a, b) => a === b
+
 module FloatFloatMap = {
   module Id = Belt.Id.MakeComparable({
     type t = float
@@ -49,6 +52,7 @@ module Tuple2 = {
     let (_, b) = v
     b
   }
+  let toFnCall = (fn, (a1, a2)) => fn(a1, a2)
 }
 
 module O = {
@@ -525,6 +529,7 @@ module A = {
   let unsafe_get = Array.unsafe_get
   let get = Belt.Array.get
   let getBy = Belt.Array.getBy
+  let getIndexBy = Belt.Array.getIndexBy
   let last = a => get(a, length(a) - 1)
   let first = get(_, 0)
   let hasBy = (r, fn) => Belt.Array.getBy(r, fn) |> O.isSome
@@ -538,6 +543,7 @@ module A = {
   let reducei = Belt.Array.reduceWithIndex
   let isEmpty = r => length(r) < 1
   let stableSortBy = Belt.SortArray.stableSortBy
+  let toNoneIfEmpty = r => isEmpty(r) ? None : Some(r)
   let toRanges = (a: array<'a>) =>
     switch a |> Belt.Array.length {
     | 0
@@ -552,6 +558,12 @@ module A = {
       |> (x => Ok(x))
     }
 
+  let getByOpen = (a, op, bin) =>
+    switch getBy(a, r => bin(op(r))) {
+    | Some(r) => Some(op(r))
+    | None => None
+    }
+
   let tail = Belt.Array.sliceToEnd(_, 1)
 
   let zip = Belt.Array.zip
@@ -636,6 +648,19 @@ module A = {
       }
     }
     let firstSome = x => Belt.Array.getBy(x, O.isSome)
+
+    let firstSomeFn = (r: array<unit => option<'a>>): option<'a> =>
+      O.flatten(getByOpen(r, l => l(), O.isSome))
+
+    let firstSomeFnWithDefault = (r, default) => firstSomeFn(r)->O2.default(default)
+
+    let openIfAllSome = (optionals: array<option<'a>>): option<array<'a>> => {
+      if all(O.isSome, optionals) {
+        Some(optionals |> fmap(O.toExn("Warning: This should not have happened")))
+      } else {
+        None
+      }
+    }
   }
 
   module R = {
@@ -822,6 +847,7 @@ module A = {
 
 module A2 = {
   let fmap = (a, b) => A.fmap(b, a)
+  let fmapi = (a, b) => A.fmapi(b, a)
   let joinWith = (a, b) => A.joinWith(b, a)
   let filter = (a, b) => A.filter(b, a)
 }
@@ -832,4 +858,10 @@ module JsArray = {
     |> Js.Array.filter(O.isSome)
     |> Js.Array.map(O.toExn("Warning: This should not have happened"))
   let filter = Js.Array.filter
-}
+}
+
+module Dict = {
+  type t<'a> = Js.Dict.t<'a>
+  let get = Js.Dict.get
+  let keys = Js.Dict.keys
+}

packages/squiggle-lang/src/rescript/Utility/Operation.res

@@ -58,6 +58,7 @@ type operationError =
   | SampleMapNeedsNtoNFunction
   | PdfInvalidError
   | NotYetImplemented // should be removed when `klDivergence` for mixed and discrete is implemented.
+  | Other(string)
 
 @genType
 module Error = {
@@ -73,6 +74,7 @@ module Error = {
     | SampleMapNeedsNtoNFunction => "SampleMap needs a function that converts a number to a number"
     | PdfInvalidError => "This Pdf is invalid"
     | NotYetImplemented => "This pathway is not yet implemented"
+    | Other(t) => t
     }
 }