diff --git a/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Continuous.res b/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Continuous.res
index 05d94ca9..2297a3e3 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Continuous.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Continuous.res
@@ -250,7 +250,7 @@ module T = Dist({
 
   let downsample = (length, t): t =>
     t |> shapeMap(XYShape.XsConversion.proportionByProbabilityMass(length, integral(t).xyShape))
-  let integralEndY = (t: t) => t.integralSumCache |> E.O.default(t |> integral |> lastY)
+  let integralEndY = (t: t) => t.integralSumCache |> E.O.defaultFn(() => t |> integral |> lastY)
   let integralXtoY = (f, t: t) => t |> integral |> shapeFn(XYShape.XtoY.linear(f))
   let integralYtoX = (f, t: t) => t |> integral |> shapeFn(XYShape.YtoX.linear(f))
   let toContinuous = t => Some(t)
diff --git a/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Discrete.res b/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Discrete.res
index 7e7c4981..b7d5ffd4 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Discrete.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Discrete.res
@@ -158,7 +158,8 @@ module T = Dist({
       Continuous.make(~interpolation=#Stepwise, integralShape)
     }
 
-  let integralEndY = (t: t) => t.integralSumCache |> E.O.default(t |> integral |> Continuous.lastY)
+  let integralEndY = (t: t) =>
+    t.integralSumCache |> E.O.defaultFn(() => t |> integral |> Continuous.lastY)
   let minX = shapeFn(XYShape.T.minX)
   let maxX = shapeFn(XYShape.T.maxX)
   let toDiscreteProbabilityMassFraction = _ => 1.0
diff --git a/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/MixedShapeBuilder.res b/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/MixedShapeBuilder.res
index 89273283..f4407ba8 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/MixedShapeBuilder.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/MixedShapeBuilder.res
@@ -13,9 +13,11 @@ let buildSimple = (
   ~discrete: option<PointSetTypes.discreteShape>,
 ): option<PointSetTypes.pointSetDist> => {
   let continuous =
-    continuous |> E.O.default(Continuous.make(~integralSumCache=Some(0.0), {xs: [], ys: []}))
+    continuous |> E.O.defaultFn(() =>
+      Continuous.make(~integralSumCache=Some(0.0), {xs: [], ys: []})
+    )
   let discrete =
-    discrete |> E.O.default(Discrete.make(~integralSumCache=Some(0.0), {xs: [], ys: []}))
+    discrete |> E.O.defaultFn(() => Discrete.make(~integralSumCache=Some(0.0), {xs: [], ys: []}))
   let cLength = continuous |> Continuous.getShape |> XYShape.T.xs |> E.A.length
   let dLength = discrete |> Discrete.getShape |> XYShape.T.xs |> E.A.length
   switch (cLength, dLength) {
diff --git a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExternalLibrary.res b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExternalLibrary.res
index fc0a2821..7ae6ace9 100644
--- a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExternalLibrary.res
+++ b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExternalLibrary.res
@@ -16,7 +16,7 @@ let dispatch = (
     () => ReducerInterface_Duration.dispatch(call, environment),
     () => ReducerInterface_Number.dispatch(call, environment),
     () => FunctionRegistry_Library.dispatch(call, environment, reducer),
-  ])->E.O2.default(chain(call, environment, reducer))
+  ])->E.O2.defaultFn(() => chain(call, environment, reducer))
 }
 
 /*
diff --git a/packages/squiggle-lang/src/rescript/Utility/E.res b/packages/squiggle-lang/src/rescript/Utility/E.res
index 50a28382..22c8c525 100644
--- a/packages/squiggle-lang/src/rescript/Utility/E.res
+++ b/packages/squiggle-lang/src/rescript/Utility/E.res
@@ -82,6 +82,11 @@ module O = {
     | None => d
     | Some(a) => a
     }
+  let defaultFn = (d, o) =>
+    switch o {
+    | None => d()
+    | Some(a) => a
+    }
   let isSome = o =>
     switch o {
     | Some(_) => true
@@ -158,6 +163,7 @@ module O = {
 
 module O2 = {
   let default = (a, b) => O.default(b, a)
+  let defaultFn = (a, b) => O.defaultFn(b, a)
   let toExn = (a, b) => O.toExn(b, a)
   let fmap = (a, b) => O.fmap(b, a)
   let toResult = (a, b) => O.toResult(b, a)