diff --git a/src/distPlus/expressionTree/ExpressionTree.re b/src/distPlus/expressionTree/ExpressionTree.re
index 86e65fbb..2611a432 100644
--- a/src/distPlus/expressionTree/ExpressionTree.re
+++ b/src/distPlus/expressionTree/ExpressionTree.re
@@ -24,7 +24,6 @@ let rec toString: node => string =
     ++ toString(internal)
     ++ ")]"
   | `Array(_) => "Array"
-  | `MultiModal(_) => "Multimodal"
   | `Hash(_) => "Hash"
 
 let envs = (samplingInputs, environment) => {
diff --git a/src/distPlus/expressionTree/ExpressionTreeEvaluator.re b/src/distPlus/expressionTree/ExpressionTreeEvaluator.re
index 9f3702e9..82eb99c2 100644
--- a/src/distPlus/expressionTree/ExpressionTreeEvaluator.re
+++ b/src/distPlus/expressionTree/ExpressionTreeEvaluator.re
@@ -307,6 +307,5 @@ let rec toLeaf =
     Js.log3("In function call", name, args);
     callableFunction(evaluationParams, name, args)
     |> E.R.bind(_, toLeaf(evaluationParams));
-  | `MultiModal(r) => Error("Multimodal?")
   };
 };
diff --git a/src/distPlus/expressionTree/ExpressionTypes.re b/src/distPlus/expressionTree/ExpressionTypes.re
index 33d1d0d1..07428c85 100644
--- a/src/distPlus/expressionTree/ExpressionTypes.re
+++ b/src/distPlus/expressionTree/ExpressionTypes.re
@@ -30,16 +30,18 @@ module ExpressionTree = {
     | `Render(node)
     | `Truncate(option(float), option(float), node)
     | `FunctionCall(string, array(node))
-    | `MultiModal(array((node, float)))
   ];
 
   module Hash = {
     type t('a) = array((string, 'a));
-    let getByName = (t:t('a), name) =>
+    let getByName = (t: t('a), name) =>
       E.A.getBy(t, ((n, _)) => n == name) |> E.O.fmap(((_, r)) => r);
 
-    let getByNames = (hash: t('a), names:array(string)) =>
-      names |> E.A.fmap(name => (name, getByName(hash, name)))
+    let getByNameResult = (t: t('a), name) =>
+      getByName(t, name) |> E.O.toResult(name ++ " expected and not found");
+
+    let getByNames = (hash: t('a), names: array(string)) =>
+      names |> E.A.fmap(name => (name, getByName(hash, name)));
   };
   // Have nil as option
   let getFloat = (node: node) =>
diff --git a/src/distPlus/expressionTree/Fns.re b/src/distPlus/expressionTree/Fns.re
index 4fdbc519..9d5983c5 100644
--- a/src/distPlus/expressionTree/Fns.re
+++ b/src/distPlus/expressionTree/Fns.re
@@ -107,6 +107,80 @@ let verticalScaling = (scaleOp, rs, scaleBy) => {
   );
 };
 
+module Multimodal = {
+  let getByNameResult = ExpressionTypes.ExpressionTree.Hash.getByNameResult;
+
+  let _paramsToDistsAndWeights = (r: array(typedValue)) =>
+    switch (r) {
+    | [|`Named(r)|] =>
+      let dists =
+        getByNameResult(r, "dists")
+        ->E.R.bind(TypeSystem.TypedValue.toArray)
+        ->E.R.bind(r =>
+            r
+            |> E.A.fmap(TypeSystem.TypedValue.toDist)
+            |> E.A.R.firstErrorOrOpen
+          );
+      let weights =
+        getByNameResult(r, "weights")
+        ->E.R.bind(TypeSystem.TypedValue.toArray)
+        ->E.R.bind(r =>
+            r
+            |> E.A.fmap(TypeSystem.TypedValue.toFloat)
+            |> E.A.R.firstErrorOrOpen
+          );
+
+      E.R.merge(dists, weights)
+      |> E.R.fmap(((a, b)) =>
+           E.A.zipMaxLength(a, b)
+           |> E.A.fmap(((a, b)) =>
+                (a |> E.O.toExn(""), b |> E.O.default(1.0))
+              )
+         );
+    | _ => Error("Needs items")
+    };
+  let _runner: array(typedValue) => result(node, string) =
+    r => {
+      let paramsToDistsAndWeights =
+        _paramsToDistsAndWeights(r)
+        |> E.R.fmap(
+             E.A.fmap(((dist, weight)) =>
+               `FunctionCall((
+                 "scaleMultiply",
+                 [|dist, `SymbolicDist(`Float(weight))|],
+               ))
+             ),
+           );
+      let pointwiseSum: result(node, string) =
+        paramsToDistsAndWeights->E.R.bind(
+          E.R.errorIfCondition(E.A.isEmpty, "Needs one input"),
+        )
+        |> E.R.fmap(r =>
+             r
+             |> Js.Array.sliceFrom(1)
+             |> E.A.fold_left(
+                  (acc, x) => {`PointwiseCombination((`Add, acc, x))},
+                  E.A.unsafe_get(r, 0),
+                )
+           );
+      pointwiseSum;
+    };
+
+  let _function =
+    Function.T.make(
+      ~name="multimodal",
+      ~outputType=`SamplingDistribution,
+      ~inputTypes=[|
+        `Named([|
+          ("dists", `Array(`SamplingDistribution)),
+          ("weights", `Array(`Float)),
+        |]),
+      |],
+      ~run=_runner,
+      (),
+    );
+};
+
 let functions = [|
   makeSymbolicFromTwoFloats("normal", SymbolicDist.Normal.make),
   makeSymbolicFromTwoFloats("uniform", SymbolicDist.Uniform.make),
@@ -175,98 +249,5 @@ let functions = [|
   makeRenderedDistFloat("scaleLog", (dist, float) =>
     verticalScaling(`Log, dist, float)
   ),
-  Function.T.make(
-    ~name="multimodal",
-    ~outputType=`SamplingDistribution,
-    ~inputTypes=[|
-      `Named([|
-        ("dists", `Array(`SamplingDistribution)),
-        ("weights", `Array(`Float)),
-      |]),
-    |],
-    ~run=
-      fun
-      | [|`Named(r)|] => {
-          let foo =
-              (r: TypeSystem.typedValue)
-              : result(ExpressionTypes.ExpressionTree.node, string) =>
-            switch (r) {
-            | `SamplingDist(`SymbolicDist(c)) => Ok(`SymbolicDist(c))
-            | `SamplingDist(`RenderedDist(c)) => Ok(`RenderedDist(c))
-            | `Float(x) =>
-              Ok(`RenderedDist(SymbolicDist.T.toShape(1000, `Float(x))))
-            | _ => Error("")
-            };
-          let weight = (r: TypeSystem.typedValue) =>
-            switch (r) {
-            | `Float(x) => Ok(x)
-            | _ => Error("Wrong Type")
-            };
-          let dists =
-            switch (ExpressionTypes.ExpressionTree.Hash.getByName(r, "dists")) {
-            | Some(`Array(r)) => r |> E.A.fmap(foo) |> E.A.R.firstErrorOrOpen
-            | _ => Error("")
-            };
-          let weights =
-            (
-              switch (
-                ExpressionTypes.ExpressionTree.Hash.getByName(r, "weights")
-              ) {
-              | Some(`Array(r)) =>
-                r |> E.A.fmap(weight) |> E.A.R.firstErrorOrOpen
-              | _ => Error("")
-              }
-            )
-            |> (
-              fun
-              | Ok(r) => r
-              | _ => [||]
-            );
-          let withWeights =
-            dists
-            |> E.R.fmap(d => {
-                 let iis =
-                   d |> E.A.length |> Belt.Array.makeUninitializedUnsafe;
-                 for (i in 0 to (d |> E.A.length) - 1) {
-                   Belt.Array.set(
-                     iis,
-                     i,
-                     (
-                       E.A.unsafe_get(d, i),
-                       E.A.get(weights, i) |> E.O.default(1.0),
-                     ),
-                   )
-                   |> ignore;
-                 };
-                 iis;
-               });
-          let components: result(array(node), string) =
-            withWeights
-            |> E.R.fmap(
-                 E.A.fmap(((dist, weight)) =>
-                   `FunctionCall((
-                     "scaleMultiply",
-                     [|dist, `SymbolicDist(`Float(weight))|],
-                   ))
-                 ),
-               );
-          let pointwiseSum =
-            components
-            |> E.R.bind(_, r => {
-                 E.A.length(r) > 0
-                   ? Ok(r) : Error("Invalid argument length")
-               })
-            |> E.R.fmap(r =>
-                 r
-                 |> Js.Array.sliceFrom(1)
-                 |> E.A.fold_left(
-                      (acc, x) => {`PointwiseCombination((`Add, acc, x))},
-                      E.A.unsafe_get(r, 0),
-                    )
-               );
-          pointwiseSum;
-        }
-      | _ => Error(""),
-    (),
-  ),
+  Multimodal._function
 |];
diff --git a/src/distPlus/expressionTree/TypeSystem.re b/src/distPlus/expressionTree/TypeSystem.re
index cda9ad27..4e39e753 100644
--- a/src/distPlus/expressionTree/TypeSystem.re
+++ b/src/distPlus/expressionTree/TypeSystem.re
@@ -54,7 +54,6 @@ module TypedValue = {
 
   // todo: Arrays and hashes
   let rec fromNodeWithTypeCoercion = (evaluationParams, _type: _type, node) => {
-    Js.log3("With Coersion!", _type, node);
     switch (_type, node) {
     | (`Float, _) =>
       switch (getFloat(node)) {
@@ -76,7 +75,6 @@ module TypedValue = {
       |> E.A.R.firstErrorOrOpen
       |> E.R.fmap(r => `Array(r))
     | (`Named(named), `Hash(r)) =>
-      Js.log3("Named", named, r);
       let foo =
         named
         |> E.A.fmap(((name, intendedType)) =>
@@ -86,7 +84,6 @@ module TypedValue = {
                ExpressionTypes.ExpressionTree.Hash.getByName(r, name),
              )
            );
-      Js.log("Named: part 2");
       let bar =
         foo
         |> E.A.fmap(((name, intendedType, optionNode)) =>
@@ -99,11 +96,33 @@ module TypedValue = {
            )
         |> E.A.R.firstErrorOrOpen
         |> E.R.fmap(r => `Named(r));
-      Js.log3("Named!", foo, bar);
       bar;
     | _ => Error("fromNodeWithTypeCoercion error, sorry.")
     };
   };
+
+  let toFloat =
+    fun
+    | `Float(x) => Ok(x)
+    | _ => Error("Not a float");
+
+  let toArray =
+    fun
+    | `Array(x) => Ok(x)
+    | _ => Error("Not an array");
+
+  let toNamed =
+    fun
+    | `Named(x) => Ok(x)
+    | _ => Error("Not a named item");
+
+  let toDist =
+    fun
+    | `SamplingDist(`SymbolicDist(c)) => Ok(`SymbolicDist(c))
+    | `SamplingDist(`RenderedDist(c)) => Ok(`RenderedDist(c))
+    | `Float(x) =>
+      Ok(`RenderedDist(SymbolicDist.T.toShape(1000, `Float(x))))
+    | _ => Error("");
 };
 
 module Function = {
diff --git a/src/distPlus/renderers/DistPlusRenderer.re b/src/distPlus/renderers/DistPlusRenderer.re
index 70f720e0..10c37ea7 100644
--- a/src/distPlus/renderers/DistPlusRenderer.re
+++ b/src/distPlus/renderers/DistPlusRenderer.re
@@ -144,7 +144,6 @@ let renderIfNeeded =
   node
   |> (
     fun
-    | `MultiModal(_) as n
     | `Normalize(_) as n
     | `SymbolicDist(_) as n => {
         `Render(n)
diff --git a/src/distPlus/utility/E.re b/src/distPlus/utility/E.re
index 175c2847..505b1d0d 100644
--- a/src/distPlus/utility/E.re
+++ b/src/distPlus/utility/E.re
@@ -26,6 +26,9 @@ module FloatFloatMap = {
   let fmap = (fn, t: t) => Belt.MutableMap.map(t, fn);
 };
 
+module Int = {
+  let max = (i1: int, i2: int) => i1 > i2 ? i1 : i2;
+};
 /* Utils */
 module U = {
   let isEqual = (a, b) => a == b;
@@ -146,6 +149,11 @@ module R = {
   let fmap = Rationale.Result.fmap;
   let bind = Rationale.Result.bind;
   let toExn = Belt.Result.getExn;
+  let default = (default, res: Belt.Result.t('a, 'b)) =>
+    switch (res) {
+    | Ok(r) => r
+    | Error(_) => default
+    };
   let merge = (a, b) =>
     switch (a, b) {
     | (Error(e), _) => Error(e)
@@ -157,6 +165,9 @@ module R = {
     | Ok(r) => Some(r)
     | Error(_) => None
     };
+
+  let errorIfCondition = (errorCondition, errorMessage, r) =>
+    errorCondition(r) ? Error(errorMessage) : Ok(r);
 };
 
 let safe_fn_of_string = (fn, s: string): option('a) =>
@@ -263,6 +274,7 @@ module A = {
   let init = Array.init;
   let reduce = Belt.Array.reduce;
   let reducei = Belt.Array.reduceWithIndex;
+  let isEmpty = r => length(r) < 1;
   let min = a =>
     get(a, 0)
     |> O.fmap(first => Belt.Array.reduce(a, first, (i, j) => i < j ? i : j));
@@ -285,6 +297,16 @@ module A = {
       |> Rationale.Result.return
     };
 
+  // This zips while taking the longest elements of each array.
+  let zipMaxLength = (array1, array2) => {
+    let maxLength = Int.max(length(array1), length(array2));
+    let result = maxLength |> Belt.Array.makeUninitializedUnsafe;
+    for (i in 0 to maxLength - 1) {
+      Belt.Array.set(result, i, (get(array1, i), get(array2, i))) |> ignore;
+    };
+    result;
+  };
+
   let asList = (f: list('a) => list('a), r: array('a)) =>
     r |> to_list |> f |> of_list;
   /* TODO: Is there a better way of doing this? */