diff --git a/packages/squiggle-lang/benchmark/Benchmark_Array.res b/packages/squiggle-lang/benchmark/Benchmark_Array.res
new file mode 100644
index 00000000..61562732
--- /dev/null
+++ b/packages/squiggle-lang/benchmark/Benchmark_Array.res
@@ -0,0 +1,76 @@
+module Map: Benchmark_Helpers.BenchmarkTopic = {
+  let arraySize = 1000
+  let iterations = 300_000
+
+  let beltArray = () => {
+    let x = Belt.Array.make(arraySize, 0.)
+    Belt.Range.forEach(1, iterations, _ => {
+      let _ = x->Belt.Array.map(v => v)
+    })
+  }
+
+  let jsArray2 = () => {
+    let x = Belt.Array.make(arraySize, 0.)
+    Belt.Range.forEach(1, iterations, _ => {
+      let _ = x->Js.Array2.map(v => v)
+    })
+  }
+
+  let ocamlArray = () => {
+    let x = Belt.Array.make(arraySize, 0.)
+    Belt.Range.forEach(1, iterations, _ => {
+      let _ = x->Array.map(v => v, _)
+    })
+  }
+
+  let runAll = () => {
+    Js.log(`Mapping identity function over arrays of size ${arraySize->Js.Int.toString} (${iterations->Js.Int.toString} iterations)`)
+    Benchmark_Helpers.measure("Belt.Array.map", beltArray)
+    Benchmark_Helpers.measure("Js.Array2.map", jsArray2)
+    Benchmark_Helpers.measure("Array.map", ocamlArray)
+  }
+}
+
+module Sort: Benchmark_Helpers.BenchmarkTopic = {
+  let arraySize = 1000
+  let iterations = 30000
+
+  let jsArray2 = () => {
+    let x = Belt.Array.make(arraySize, 0.)
+    let compare = (a: float, b: float) => {
+      if a < b {
+        -1
+      } else {
+        1
+      }
+    }
+
+    Belt.Range.forEach(1, iterations, _ => {
+      let _ = x->Js.Array2.sortInPlaceWith(compare)
+    })
+  }
+
+  let jsArray2withOcamlCompare = () => {
+    let x = Belt.Array.make(arraySize, 0.)
+    Belt.Range.forEach(1, iterations, _ => {
+      let _ = x->Js.Array2.sortInPlaceWith(Pervasives.compare)
+    })
+  }
+
+  let ocamlArray = () => {
+    let x = Belt.Array.make(arraySize, 0.)
+    Belt.Range.forEach(1, iterations, _ => {
+      let _ = x->Array.fast_sort(compare, _)
+    })
+  }
+
+  let runAll = () => {
+    Js.log(`Sorting arrays of size ${arraySize->Js.Int.toString} (${iterations->Js.Int.toString} iterations)`)
+    Benchmark_Helpers.measure("Js.Array2.sort", jsArray2)
+    Benchmark_Helpers.measure("Js.Array2.sort with Ocaml compare", jsArray2withOcamlCompare)
+    Benchmark_Helpers.measure("Array.fast_sort", ocamlArray)
+  }
+}
+
+Map.runAll()
+Sort.runAll()
diff --git a/packages/squiggle-lang/benchmark/Benchmark_Helpers.res b/packages/squiggle-lang/benchmark/Benchmark_Helpers.res
new file mode 100644
index 00000000..0e889d15
--- /dev/null
+++ b/packages/squiggle-lang/benchmark/Benchmark_Helpers.res
@@ -0,0 +1,11 @@
+module type BenchmarkTopic = {
+  let runAll: () => unit
+}
+
+let measure = (name: string, f: () => unit) => {
+    let start = Js.Date.make()->Js.Date.valueOf
+    f()
+    let end = Js.Date.make()->Js.Date.valueOf
+    let duration = (end -. start) /. 1000.
+    Js.log2(duration, name)
+}
diff --git a/packages/squiggle-lang/benchmark/Benchmark_Map.res b/packages/squiggle-lang/benchmark/Benchmark_Map.res
new file mode 100644
index 00000000..d04d501d
--- /dev/null
+++ b/packages/squiggle-lang/benchmark/Benchmark_Map.res
@@ -0,0 +1,65 @@
+module StringMap: Benchmark_Helpers.BenchmarkTopic = {
+  let size = 1000
+  let iterations = 10_000
+
+    let kv = Belt.Array.range(1, size)->Belt.Array.map(
+        v => ("key" ++ v->Belt.Int.toString, v)
+    )
+
+  let beltMap = () => {
+    Belt.Range.forEach(1, iterations, _ => {
+        let m = Belt.Map.String.empty
+        let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => acc->Belt.Map.String.set(k, v))
+    })
+  }
+
+  let beltMutableMap = () => {
+    Belt.Range.forEach(1, iterations, _ => {
+        let m = Belt.MutableMap.String.make()
+        let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => {
+            acc->Belt.MutableMap.String.set(k, v)
+            acc
+        })
+    })
+  }
+
+  let beltHashMap = () => {
+    Belt.Range.forEach(1, iterations, _ => {
+        let m = Belt.HashMap.String.make(~hintSize=100)
+        let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => {
+            acc->Belt.HashMap.String.set(k, v)
+            acc
+        })
+    })
+  }
+
+  let jsDict = () => {
+    Belt.Range.forEach(1, iterations, _ => {
+        let m = Js.Dict.empty()
+        let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => {
+            acc->Js.Dict.set(k, v)
+            acc
+        })
+    })
+  }
+
+  let jsMap = () => {
+    Belt.Range.forEach(1, iterations, _ => {
+        let m = Js_map.make()
+        let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) =>
+            acc->Js_map.set(k, v)
+        )
+    })
+  }
+
+  let runAll = () => {
+      Js.log(`Filling a map with ("key{i}" => "i") key-value pairs, size ${size->Js.Int.toString} (${iterations->Js.Int.toString} iterations)`)
+      Benchmark_Helpers.measure("Belt.Map.String", beltMap)
+      Benchmark_Helpers.measure("Belt.MutableMap.String", beltMutableMap)
+      Benchmark_Helpers.measure("Belt.HashMap.String", beltHashMap)
+      Benchmark_Helpers.measure("Js.Dict", jsDict)
+      Benchmark_Helpers.measure("Js.Map", jsMap)
+  }
+}
+
+let runAll = StringMap.runAll()
diff --git a/packages/squiggle-lang/bsconfig.json b/packages/squiggle-lang/bsconfig.json
index 1fa663ac..a05df290 100644
--- a/packages/squiggle-lang/bsconfig.json
+++ b/packages/squiggle-lang/bsconfig.json
@@ -9,6 +9,11 @@
       "dir": "__tests__",
       "type": "dev",
       "subdirs": true
+    },
+    {
+      "dir": "benchmark",
+      "type": "dev",
+      "subdirs": true
     }
   ],
   "bsc-flags": ["-bs-super-errors", "-bs-no-version-header", "-bs-g"],
@@ -21,7 +26,12 @@
   "suffix": ".bs.js",
   "namespace": true,
   "bs-dependencies": ["bisect_ppx"],
-  "bs-dev-dependencies": ["@glennsl/rescript-jest", "rescript-fast-check"],
+  "bs-dev-dependencies": [
+    "@glennsl/rescript-jest",
+    "rescript-fast-check",
+    "rescript-js-map",
+    "rescript-js-iterator"
+  ],
   "gentypeconfig": {
     "language": "typescript",
     "module": "commonjs",
diff --git a/packages/squiggle-lang/examples/integrate.squiggle b/packages/squiggle-lang/examples/integrate.squiggle
new file mode 100644
index 00000000..d41e18c7
--- /dev/null
+++ b/packages/squiggle-lang/examples/integrate.squiggle
@@ -0,0 +1,13 @@
+integrate(fun, min, max) = {
+    // assume that min and max are integers.
+    epsilon = 1
+    l = max - min
+    meanF(t) = fun(t)
+    intervals = map(List.upTo(0, (l/epsilon)), ({|n| min + n*epsilon}))
+    values = map(intervals, ({ |x | meanF(x)}))
+    result = reduce(values, 0, ({|acc, x| acc + x})) * epsilon
+    result
+}
+
+f(x) = x
+integrate(f, 1, 100k)
diff --git a/packages/squiggle-lang/package.json b/packages/squiggle-lang/package.json
index 80c542f5..89ea4432 100644
--- a/packages/squiggle-lang/package.json
+++ b/packages/squiggle-lang/package.json
@@ -66,6 +66,7 @@
     "reanalyze": "^2.23.0",
     "rescript": "^9.1.4",
     "rescript-fast-check": "^1.1.1",
+    "rescript-js-map": "^1.1.0",
     "ts-jest": "^27.1.4",
     "ts-loader": "^9.3.0",
     "ts-node": "^10.9.1",
diff --git a/packages/squiggle-lang/scripts/README.md b/packages/squiggle-lang/scripts/README.md
new file mode 100644
index 00000000..e8dea081
--- /dev/null
+++ b/packages/squiggle-lang/scripts/README.md
@@ -0,0 +1,3 @@
+Various scripts used for development, benchmarking and testing.
+
+None of these are bundled in NPM package yet.
diff --git a/packages/squiggle-lang/bench.js b/packages/squiggle-lang/scripts/bench-map-reduce.js
similarity index 61%
rename from packages/squiggle-lang/bench.js
rename to packages/squiggle-lang/scripts/bench-map-reduce.js
index effccdfa..ffada066 100755
--- a/packages/squiggle-lang/bench.js
+++ b/packages/squiggle-lang/scripts/bench-map-reduce.js
@@ -1,5 +1,5 @@
 #!/usr/bin/env node
-const s = require("./dist/src/js");
+const s = require("@quri/squiggle-lang");
 
 const measure = (cb, times = 1) => {
   const t1 = new Date();
@@ -11,17 +11,17 @@ const measure = (cb, times = 1) => {
   return (t2 - t1) / 1000;
 };
 
-const maxP = 7;
+const maxP = 5;
 
 for (let p = 0; p <= maxP; p++) {
   const size = Math.pow(10, p);
   const prj = s.SqProject.create();
-  prj.setSource("list", `l = List.upTo(1,${size})`);
-  prj.run("list");
-  prj.setSource("map", "l |> map({|x| x})");
-  prj.setContinues("map", ["list"]);
+  prj.setSource(
+    "main",
+    `List.upTo(1, ${size}) |> map({|x| List.upTo(1, 100) |> reduce(0, {|a,b|a+b})})`
+  );
   const t = measure(() => {
-    prj.run("map");
+    prj.run("main");
   });
   console.log(`1e${p}`, "\t", t);
 }
diff --git a/packages/squiggle-lang/scripts/bench-map.js b/packages/squiggle-lang/scripts/bench-map.js
new file mode 100755
index 00000000..befa1a7b
--- /dev/null
+++ b/packages/squiggle-lang/scripts/bench-map.js
@@ -0,0 +1,27 @@
+#!/usr/bin/env node
+const s = require("@quri/squiggle-lang");
+
+const measure = (cb, times = 1) => {
+  const t1 = new Date();
+
+  for (let i = 1; i <= times; i++) {
+    cb();
+  }
+  const t2 = new Date();
+  return (t2 - t1) / 1000;
+};
+
+const maxP = 7;
+
+for (let p = 0; p <= maxP; p++) {
+  const size = Math.pow(10, p);
+  const project = s.SqProject.create();
+  project.setSource("list", `l = List.upTo(1,${size})`);
+  project.run("list");
+  project.setSource("map", "l |> map({|x| x})");
+  project.setContinues("map", ["list"]);
+  const time = measure(() => {
+    project.run("map");
+  });
+  console.log(`1e${p}`, "\t", time);
+}
diff --git a/packages/squiggle-lang/scripts/run-file.js b/packages/squiggle-lang/scripts/run-file.js
new file mode 100755
index 00000000..fb09aa23
--- /dev/null
+++ b/packages/squiggle-lang/scripts/run-file.js
@@ -0,0 +1,38 @@
+#!/usr/bin/env node
+const s = require("@quri/squiggle-lang");
+const fs = require("fs");
+
+const measure = (cb, times = 1) => {
+  const t1 = new Date();
+
+  for (let i = 1; i <= times; i++) {
+    cb();
+  }
+  const t2 = new Date();
+  return (t2 - t1) / 1000;
+};
+
+const project = s.SqProject.create();
+const sampleCount = process.env.SAMPLE_COUNT;
+if (sampleCount) {
+  project.setEnvironment({
+    sampleCount,
+    xyPointLength: sampleCount,
+  });
+}
+
+const src = fs.readFileSync(process.argv[2], "utf-8");
+if (!src) {
+  throw new Error("Expected src");
+}
+console.log(`Running ${src}`);
+project.setSource("a", src);
+
+const t = measure(() => project.run("a"));
+console.log(`Time: ${t}`);
+
+const result = project.getResult("a");
+console.log("Result:", result.tag, result.value.toString());
+
+const bindings = project.getBindings("a");
+console.log("Bindings:", bindings.asValue().toString());
diff --git a/packages/squiggle-lang/scripts/run.js b/packages/squiggle-lang/scripts/run.js
new file mode 100755
index 00000000..e77b953b
--- /dev/null
+++ b/packages/squiggle-lang/scripts/run.js
@@ -0,0 +1,18 @@
+#!/usr/bin/env node
+const s = require("@quri/squiggle-lang");
+
+const p = s.SqProject.create();
+
+const src = process.argv[2];
+if (!src) {
+  throw new Error("Expected src");
+}
+console.log(`Running ${src}`);
+p.setSource("a", src);
+p.run("a");
+
+const result = p.getResult("a");
+console.log(result.tag, result.value.toString());
+
+const bindings = p.getBindings("a");
+console.log(bindings.asValue().toString());
diff --git a/yarn.lock b/yarn.lock
index 9a156c50..f4ed4bd8 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -4797,10 +4797,10 @@
     "@types/history" "^4.7.11"
     "@types/react" "*"
 
-"@types/react@*", "@types/react@^18.0.1", "@types/react@^18.0.18":
-  version "18.0.19"
-  resolved "https://registry.yarnpkg.com/@types/react/-/react-18.0.19.tgz#269a5f35b9a73c69dfb0c7189017013ab02acbaa"
-  integrity sha512-BDc3Q+4Q3zsn7k9xZrKfjWyJsSlEDMs38gD1qp2eDazLCdcPqAT+vq1ND+Z8AGel/UiwzNUk8ptpywgNQcJ1MQ==
+"@types/react@*", "@types/react@^18.0.18":
+  version "18.0.20"
+  resolved "https://registry.yarnpkg.com/@types/react/-/react-18.0.20.tgz#e4c36be3a55eb5b456ecf501bd4a00fd4fd0c9ab"
+  integrity sha512-MWul1teSPxujEHVwZl4a5HxQ9vVNsjTchVA+xRqv/VYGCuKGAU6UhfrTdF5aBefwD1BHUD8i/zq+O/vyCm/FrA==
   dependencies:
     "@types/prop-types" "*"
     "@types/scheduler" "*"
@@ -15152,7 +15152,7 @@ react-vega@^7.6.0:
     prop-types "^15.8.1"
     vega-embed "^6.5.1"
 
-react@^18.0.0, react@^18.1.0:
+react@^18.1.0:
   version "18.2.0"
   resolved "https://registry.yarnpkg.com/react/-/react-18.2.0.tgz#555bd98592883255fa00de14f1151a917b5d77d5"
   integrity sha512-/3IjMdb2L9QbBdWiW5e3P2/npwMBaU9mHCSCUzNln0ZCYbcfTsGbTJrU/kGemdH2IWmB2ioZ+zkxtmq6g09fGQ==
@@ -15578,6 +15578,18 @@ rescript-fast-check@^1.1.1:
   dependencies:
     fast-check "^2.17.0"
 
+rescript-js-iterator@^1.1.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/rescript-js-iterator/-/rescript-js-iterator-1.1.0.tgz#7fc1e6097cec5f3b847189e112deed0bca331f4d"
+  integrity sha512-9VSGfAUXdmOl0OoersJZknpGjCi4gsIuejcHQwIYKwoPPlfswFvrKjwOLTy4SoqM2037RxiwxsMPRlWgfDY22A==
+
+rescript-js-map@^1.1.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/rescript-js-map/-/rescript-js-map-1.1.0.tgz#5e4e57d9147733bd2d14307d65f0f8febb5850fc"
+  integrity sha512-kJB43pIRv/Cd9OY17Fpof+xq6WTCqagdW+zrmBxFIj8SpK48rG4nF8jXSsYK3ksdwIJwh7J3sx3pwA27YkeM+A==
+  dependencies:
+    rescript-js-iterator "^1.1.0"
+
 rescript@^9.1.4:
   version "9.1.4"
   resolved "https://registry.yarnpkg.com/rescript/-/rescript-9.1.4.tgz#1eb126f98d6c16942c0bf0df67c050198e580515"