diff --git a/packages/components/src/components/SquiggleChart.tsx b/packages/components/src/components/SquiggleChart.tsx
index 1a3c4414..2971a3e1 100644
--- a/packages/components/src/components/SquiggleChart.tsx
+++ b/packages/components/src/components/SquiggleChart.tsx
@@ -11,14 +11,15 @@ import {
   defaultImports,
   defaultBindings,
   defaultEnvironment,
-  continuousDeclaration,
+  declarationArg,
+  declaration
 } from "@quri/squiggle-lang";
 import { NumberShower } from "./NumberShower";
 import { DistributionChart } from "./DistributionChart";
 import { ErrorBox } from "./ErrorBox";
 import { FunctionChart, FunctionChartSettings } from "./FunctionChart";
 
-function getRange<a>(x: continuousDeclaration<a>) {
+function getRange<a>(x: declaration<a>) {
   let first = x.args[0];
   switch (first.tag) {
     case "Float": {
@@ -30,7 +31,7 @@ function getRange<a>(x: continuousDeclaration<a>) {
   }
 }
 function getChartSettings<a>(
-  x: continuousDeclaration<a>
+  x: declaration<a>
 ): FunctionChartSettings {
   let range = getRange(x);
   let min = range.floats ? range.floats.min : 0;
@@ -240,27 +241,17 @@ const SquiggleItem: React.FC<SquiggleItemProps> = ({
         />
       );
     case "lambdaDeclaration": {
-      switch (expression.value.tag) {
-        case "Continuous": {
           return (
             <FunctionChart
-              fn={expression.value.value.fn}
-              chartSettings={getChartSettings(expression.value.value)}
+              fn={expression.value.fn}
+              chartSettings={getChartSettings(expression.value)}
               environment={{
                 sampleCount: environment.sampleCount / 10,
                 xyPointLength: environment.xyPointLength / 10,
               }}
             />
           );
-        }
-        case "RelativeComparison": {
-          return <>"Relative"</>;
-        }
-        default: {
-          return <>LambdaDeclaration: Should be unreachable</>;
-        }
       }
-    }
     default: {
       return <>Should be unreachable</>;
     }
diff --git a/packages/squiggle-lang/src/js/index.ts b/packages/squiggle-lang/src/js/index.ts
index f06dac99..03068a51 100644
--- a/packages/squiggle-lang/src/js/index.ts
+++ b/packages/squiggle-lang/src/js/index.ts
@@ -14,9 +14,8 @@ export {
   errorValueToString,
   distributionErrorToString,
   distributionError,
-  continuousDeclaration,
-  relativeComparisonDeclaration,
-  declarationContinuousArg,
+  declarationArg,
+  declaration,
 } from "../rescript/TypescriptInterface.gen";
 export type { errorValue, externalBindings as bindings, jsImports };
 import {
diff --git a/packages/squiggle-lang/src/js/rescript_interop.ts b/packages/squiggle-lang/src/js/rescript_interop.ts
index 9d521927..64e7a64f 100644
--- a/packages/squiggle-lang/src/js/rescript_interop.ts
+++ b/packages/squiggle-lang/src/js/rescript_interop.ts
@@ -9,7 +9,8 @@ import {
   discreteShape,
   continuousShape,
   lambdaValue,
-  lambdaDeclaration
+  lambdaDeclaration,
+  declarationArg,
 } from "../rescript/TypescriptInterface.gen";
 import { Distribution } from "./distribution";
 import { tagged, tag } from "./types";
@@ -67,7 +68,7 @@ export type rescriptExport =
     }
   | {
       TAG: 12; // EvDeclaration
-      _0: lambdaDeclaration;
+      _0: rescriptLambdaDeclaration;
     };
 
 type rescriptDist =
@@ -89,6 +90,23 @@ type rescriptPointSetDist =
       _0: continuousShape;
     };
 
+type rescriptLambdaDeclaration = {
+  readonly fn: lambdaValue;
+  readonly args: rescriptDeclarationArg[];
+};
+
+type rescriptDeclarationArg =
+  | {
+      TAG: 0; // Float
+      min: number;
+      max: number;
+    }
+  | {
+      TAG: 1; // Float
+      min: Date;
+      max: Date;
+    };
+
 export type squiggleExpression =
   | tagged<"symbol", string>
   | tagged<"string", string>
@@ -148,7 +166,21 @@ export function convertRawToTypescript(
     case 11: // EvTimeDuration
       return tag("number", result._0);
     case 12: // EvDeclaration
-      return tag("lambdaDeclaration", result._0);
+      return tag("lambdaDeclaration", {
+        fn: result._0.fn,
+        args: result._0.args.map(convertDeclaration),
+      });
+  }
+}
+
+function convertDeclaration(
+  declarationArg: rescriptDeclarationArg
+): declarationArg {
+  switch (declarationArg.TAG) {
+    case 0: // Float
+      return tag("Float", { min: declarationArg.min, max: declarationArg.max });
+    case 1: // Date
+      return tag("Date", { min: declarationArg.min, max: declarationArg.max });
   }
 }
 
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res
index da5260c6..582df17d 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res
@@ -78,9 +78,9 @@ module FRType = {
     | (FRTypeOption(v), _) => Some(FRValueOption(matchWithExpressionValue(v, r)))
     | (FRTypeLambda, EvLambda(f)) => Some(FRValueLambda(f))
     | (FRTypeArray(intendedType), EvArray(elements)) => {
-      let el = elements->E.A2.fmap(matchWithExpressionValue(intendedType))
-      E.A.O.openIfAllSome(el)->E.O2.fmap(r => FRValueArray(r))
-    }
+        let el = elements->E.A2.fmap(matchWithExpressionValue(intendedType))
+        E.A.O.openIfAllSome(el)->E.O2.fmap(r => FRValueArray(r))
+      }
     | (FRTypeRecord(recordParams), EvRecord(record)) => {
         let getAndMatch = (name, input) =>
           E.Dict.get(record, name)->E.O.bind(matchWithExpressionValue(input))
@@ -96,23 +96,24 @@ module FRType = {
     }
 
   let rec matchReverse = (e: frValue): expressionValue =>
-  switch(e){
-    | FRValueNumber(f) => (EvNumber(f))
+    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)
-    }
+        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
+  // | FRValueOption(None) => break
   let matchWithExpressionValueArray = (inputs: array<t>, args: array<expressionValue>): option<
     array<frValue>,
   > => {
diff --git a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res
index 39f20d4d..54933d20 100644
--- a/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res
+++ b/packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res
@@ -21,7 +21,7 @@ module Declaration = {
         ->E.A2.fmap(getMinMax)
         ->E.A.R.firstErrorOrOpen
         ->E.R2.fmap(args => ReducerInterface_ExpressionValue.EvDeclaration(
-          Declaration.ContinuousDeclaration.make(lambda, args),
+          Declaration.make(lambda, args),
         ))
       }
     | _ => Error("Error")
@@ -35,8 +35,7 @@ let registry = [
     ~definitions=[
       FnDefinition.make(~name="declareFn", ~inputs=[Declaration.frType], ~run=(inputs, _) => {
         inputs->E.A.unsafe_get(0)->Declaration.fromExpressionValue
-      }
-      ),
+      }),
     ],
   ),
   Function.make(
diff --git a/packages/squiggle-lang/src/rescript/TypescriptInterface.res b/packages/squiggle-lang/src/rescript/TypescriptInterface.res
index e6170366..932edaa1 100644
--- a/packages/squiggle-lang/src/rescript/TypescriptInterface.res
+++ b/packages/squiggle-lang/src/rescript/TypescriptInterface.res
@@ -92,13 +92,7 @@ let defaultEnvironment = ReducerInterface_ExpressionValue.defaultEnvironment
 let foreignFunctionInterface = Reducer.foreignFunctionInterface
 
 @genType
-type declarationContinuousArg = Declaration.continuousArg
-
-@genType
-type continuousDeclaration<'a> = Declaration.continuousDeclaration<'a>
-
-@genType
-type relativeComparisonDeclaration<'a> = Declaration.relativeComparisonDeclaration<'a>
+type declarationArg = Declaration.arg
 
 @genType
 type declaration<'a> = Declaration.declaration<'a>
diff --git a/packages/squiggle-lang/src/rescript/Utility/Declaration.res b/packages/squiggle-lang/src/rescript/Utility/Declaration.res
index 188f01ca..d26e1833 100644
--- a/packages/squiggle-lang/src/rescript/Utility/Declaration.res
+++ b/packages/squiggle-lang/src/rescript/Utility/Declaration.res
@@ -1,33 +1,24 @@
 @genType
-type continuousArg = Float({min: float, max: float}) | Time({min: Js.Date.t, max: Js.Date.t})
+type arg = Float({min: float, max: float}) | Date({min: Js.Date.t, max: Js.Date.t})
+
 @genType
-type continuousDeclaration<'a> = {fn: 'a, args: array<continuousArg>}
-@genType
-type relativeComparisonDeclaration<'a> = {fn: 'a, options: array<string>}
-@genType
-type declaration<'a> =
-  Continuous(continuousDeclaration<'a>) | RelativeComparison(relativeComparisonDeclaration<'a>)
+type declaration<'a> = {
+  fn: 'a,
+  args: array<arg>,
+}
 
 module ContinuousFloatArg = {
-  let make = (min: float, max: float): continuousArg => {
+  let make = (min: float, max: float): arg => {
     Float({min: min, max: max})
   }
 }
 
 module ContinuousTimeArg = {
-  let make = (min: Js.Date.t, max: Js.Date.t): continuousArg => {
-    Time({min: min, max: max})
+  let make = (min: Js.Date.t, max: Js.Date.t): arg => {
+    Date({min: min, max: max})
   }
 }
 
-module ContinuousDeclaration = {
-  let make = (fn: 'a, args: array<continuousArg>): declaration<'a> => {
-    Continuous({fn: fn, args: args})
-  }
-}
-
-module RelativeComparisonDeclaration = {
-  let make = (fn: 'a, options: array<string>): declaration<'a> => {
-    RelativeComparison({fn: fn, options: options})
-  }
+let make = (fn: 'a, args: array<arg>): declaration<'a> => {
+  {fn: fn, args: args}
 }