diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res
index 99ecc78f..a88ce239 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res
@@ -8,9 +8,12 @@ type rec frType =
   | FRTypeNumber
   | FRTypeNumeric
   | FRTypeDistOrNumber
+  | FRTLambda
   | FRTypeRecord(frTypeRecord)
-  | FRTypeArray(array<frType>)
+  | FRTypeArray(frType)
   | FRTypeOption(frType)
+  | FRTypeString
+  | FRTypeVariant(array<string>)
 and frTypeRecord = array<frTypeRecordParam>
 and frTypeRecordParam = (string, frType)
 
@@ -22,8 +25,12 @@ type rec frValue =
   | FRValueNumber(float)
   | FRValueDist(DistributionTypes.genericDist)
   | FRValueOption(option<frValue>)
+  | FRValueArray(array<frValue>)
   | FRValueDistOrNumber(frValueDistOrNumber)
   | FRValueRecord(frValueRecord)
+  | FRValueLambda(ReducerInterface_ExpressionValue.lambdaValue)
+  | FRValueString(string)
+  | FRValueVariant(string)
 and frValueRecord = array<frValueRecordParam>
 and frValueRecordParam = (string, frValue)
 and frValueDistOrNumber = FRValueNumber(float) | FRValueDist(DistributionTypes.genericDist)
@@ -52,8 +59,9 @@ module FRType = {
         let input = ((name, frType): frTypeRecordParam) => `${name}: ${toString(frType)}`
         `record({${r->E.A2.fmap(input)->E.A2.joinWith(", ")}})`
       }
-    | FRTypeArray(r) => `record(${r->E.A2.fmap(toString)->E.A2.joinWith(", ")})`
+    | FRTypeArray(r) => `record(${toString(r)})`
     | FRTypeOption(v) => `option(${toString(v)})`
+    | FRTLambda => `lambda`
     }
 
   let rec matchWithExpressionValue = (t: t, r: expressionValue): option<frValue> =>
@@ -66,6 +74,7 @@ module FRType = {
     | (FRTypeNumeric, EvNumber(f)) => Some(FRValueNumber(f))
     | (FRTypeNumeric, EvDistribution(Symbolic(#Float(f)))) => Some(FRValueNumber(f))
     | (FRTypeOption(v), _) => Some(FRValueOption(matchWithExpressionValue(v, r)))
+    | (FRTLambda, EvLambda(f)) => Some(FRValueLambda(f))
     | (FRTypeRecord(recordParams), EvRecord(record)) => {
         let getAndMatch = (name, input) =>
           E.Dict.get(record, name)->E.O.bind(matchWithExpressionValue(input))
@@ -80,6 +89,24 @@ module FRType = {
     | _ => None
     }
 
+  let rec matchReverse = (e: frValue): expressionValue =>
+  switch(e){
+    | FRValueNumber(f) => (EvNumber(f))
+    | FRValueDistOrNumber(FRValueNumber(n)) => EvNumber(n)
+    | FRValueDistOrNumber(FRValueDist(n)) => EvDistribution(n)
+    | FRValueDist(dist) => EvDistribution(dist)
+    | FRValueOption(Some(r)) => matchReverse(r)
+    | FRValueArray(elements) => EvArray(elements->E.A2.fmap(matchReverse))
+    | FRValueRecord(frValueRecord) => {
+      let record = frValueRecord->E.A2.fmap(((name, value)) => (name, matchReverse(value)))->E.Dict.fromArray
+      EvRecord(record)
+    }
+    | FRValueLambda(l) => EvLambda(l)
+    | FRValueString(string) => EvString(string)
+    | FRValueVariant(string) => EvString(string)
+  }
+
+    // | FRValueOption(None) => break
   let matchWithExpressionValueArray = (inputs: array<t>, args: array<expressionValue>): option<
     array<frValue>,
   > => {
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.resi b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.resi
deleted file mode 100644
index 5ca8c708..00000000
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.resi
+++ /dev/null
@@ -1,58 +0,0 @@
-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>>
-}
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Helpers.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Helpers.res
index 118a15d2..2d21d07a 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Helpers.res
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Helpers.res
@@ -30,6 +30,13 @@ module Prepare = {
       }
     }
 
+    let twoNumbers = (values: ts): result<(float, float), err> => {
+      switch values {
+      | [FRValueNumber(a1), FRValueNumber(a2)] => Ok(a1, a2)
+      | _ => Error(impossibleError)
+      }
+    }
+
     let oneDistOrNumber = (values: ts): result<frValueDistOrNumber, err> => {
       switch values {
       | [FRValueDistOrNumber(a1)] => Ok(a1)
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res
index 43be7118..5a12e496 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res
@@ -3,7 +3,27 @@ open FunctionRegistry_Helpers
 
 let twoArgs = E.Tuple2.toFnCall
 
+// ~run=(inputs, env) => switch(inputs->FunctionRegistry_Helpers.Prepare.ToValueArray.Record.twoArgs){
+//   | (FRTypeArray(records), FRValueLambdaValue(fn)) => {
+//     records->E.A.fmap2(r => r->FunctionRegistry_Helpers.Prepare.ToValueArray.Record.twoArgs->FunctionRegistry_Helpers.Prepare)
+//     })
+//   }
+// let variant = FRTypeVariant(["Numeric", "Date"])
+let recordType = FRTypeRecord([("min", FRTypeNumber), ("max", FRTypeNumber)])
 let registry = [
+  Function.make(
+    ~name="FnMake",
+    ~definitions=[
+      FnDefinition.make(
+        ~name="declareFn",
+        ~inputs=[FRTypeRecord([("inputs", FRTypeArray(recordType))])],
+        ~run=(inputs, _) => {
+          let foo = FunctionRegistry_Core.FRType.matchReverse(inputs->E.A.unsafe_get(0))
+          foo->Ok
+        }
+      ),
+    ],
+  ),
   Function.make(
     ~name="Normal",
     ~definitions=[
diff --git a/packages/squiggle-lang/src/rescript/Utility/E.res b/packages/squiggle-lang/src/rescript/Utility/E.res
index 3357f4f4..35d9fe4d 100644
--- a/packages/squiggle-lang/src/rescript/Utility/E.res
+++ b/packages/squiggle-lang/src/rescript/Utility/E.res
@@ -864,4 +864,5 @@ module Dict = {
   type t<'a> = Js.Dict.t<'a>
   let get = Js.Dict.get
   let keys = Js.Dict.keys
+  let fromArray = Js.Dict.fromArray
 }