diff --git a/__tests__/CDF__Test.re b/__tests__/CDF__Test.re
new file mode 100644
index 00000000..68d0bd37
--- /dev/null
+++ b/__tests__/CDF__Test.re
@@ -0,0 +1,179 @@
+open Jest;
+open Expect;
+
+exception ShapeWrong(string);
+describe("CDF", () => {
+  test("raise - w/o order", () => {
+    expect(() => {
+      module Cdf =
+        CDF.Make({
+          let shape: DistTypes.xyShape = {
+            xs: [|10., 4., 8.|],
+            ys: [|8., 9., 2.|],
+          };
+        });
+      ();
+    })
+    |> toThrow
+  });
+  test("raise - with order", () => {
+    expect(() => {
+      module Cdf =
+        CDF.Make({
+          let shape: DistTypes.xyShape = {
+            xs: [|1., 4., 8.|],
+            ys: [|8., 9., 2.|],
+          };
+        });
+      ();
+    })
+    |> not_
+    |> toThrow
+  });
+  test("order#1", () => {
+    let a = CDF.order({xs: [|1., 4., 8.|], ys: [|8., 9., 2.|]});
+    let b: DistTypes.xyShape = {xs: [|1., 4., 8.|], ys: [|8., 9., 2.|]};
+    expect(a) |> toEqual(b);
+  });
+  test("order#2", () => {
+    let a = CDF.order({xs: [|10., 5., 12.|], ys: [|8., 9., 2.|]});
+    let b: DistTypes.xyShape = {xs: [|5., 10., 12.|], ys: [|9., 8., 2.|]};
+    expect(a) |> toEqual(b);
+  });
+
+  describe("minX - maxX", () => {
+    module Dist =
+      CDF.Make({
+        let shape = CDF.order({xs: [|20., 4., 8.|], ys: [|8., 9., 2.|]});
+      });
+    test("minX", () => {
+      expect(Dist.minX()) |> toEqual(4.)
+    });
+    test("maxX", () => {
+      expect(Dist.maxX()) |> toEqual(20.)
+    });
+  });
+
+  describe("findY", () => {
+    module Dist =
+      CDF.Make({
+        let shape = CDF.order({xs: [|1., 2., 3.|], ys: [|5., 6., 7.|]});
+      });
+    test("#1", () => {
+      expect(Dist.findY(1.)) |> toEqual(5.)
+    });
+    test("#2", () => {
+      expect(Dist.findY(1.5)) |> toEqual(5.5)
+    });
+    test("#3", () => {
+      expect(Dist.findY(3.)) |> toEqual(7.)
+    });
+    test("#4", () => {
+      expect(Dist.findY(4.)) |> toEqual(7.)
+    });
+    test("#5", () => {
+      expect(Dist.findY(15.)) |> toEqual(7.)
+    });
+    test("#6", () => {
+      expect(Dist.findY(-1.)) |> toEqual(5.)
+    });
+  });
+
+  describe("findX", () => {
+    module Dist =
+      CDF.Make({
+        let shape = CDF.order({xs: [|1., 2., 3.|], ys: [|5., 6., 7.|]});
+      });
+    test("#1", () => {
+      expect(Dist.findX(5.)) |> toEqual(1.)
+    });
+    test("#2", () => {
+      expect(Dist.findX(7.)) |> toEqual(3.)
+    });
+    test("#3", () => {
+      expect(Dist.findX(5.5)) |> toEqual(1.5)
+    });
+    test("#4", () => {
+      expect(Dist.findX(8.)) |> toEqual(3.)
+    });
+    test("#5", () => {
+      expect(Dist.findX(4.)) |> toEqual(1.)
+    });
+  });
+
+  describe("convertWithAlternativeXs", () => {
+    open Functions;
+    let xs = up(1, 9);
+    let ys = up(20, 28);
+    module Dist =
+      CDF.Make({
+        let shape = CDF.order({xs, ys});
+      });
+
+    let xs2 = up(3, 7);
+    module Dist2 =
+      CDF.Make({
+        let shape = Dist.convertWithAlternativeXs(xs2);
+      });
+
+    test("#1", () => {
+      expect(Dist2.xs) |> toEqual([|3., 4., 5., 6., 7.|])
+    });
+    test("#2", () => {
+      expect(Dist2.ys) |> toEqual([|22., 23., 24., 25., 26.|])
+    });
+  });
+
+  describe("convertToNewLength", () => {
+    open Functions;
+    let xs = up(1, 9);
+    let ys = up(50, 58);
+    module Dist =
+      CDF.Make({
+        let shape = CDF.order({xs, ys});
+      });
+    module Dist2 =
+      CDF.Make({
+        let shape = Dist.convertToNewLength(3);
+      });
+    test("#1", () => {
+      expect(Dist2.xs) |> toEqual([|1., 5., 9.|])
+    });
+    test("#2", () => {
+      expect(Dist2.ys) |> toEqual([|50., 54., 58.|])
+    });
+  });
+
+  // @todo: Should each test expect 70.?
+  describe("sample", () => {
+    open Functions;
+    let xs = up(1, 9);
+    let ys = up(70, 78);
+    module Dist =
+      CDF.Make({
+        let shape = CDF.order({xs, ys});
+      });
+
+    let xs2 = Dist.sample(3);
+    test("#1", () => {
+      expect(xs2[0]) |> toBe(70.)
+    });
+    test("#2", () => {
+      expect(xs2[1]) |> toBe(70.)
+    });
+    test("#3", () => {
+      expect(xs2[2]) |> toBe(70.)
+    });
+  });
+
+  describe("integral", () => {
+    module Dist =
+      CDF.Make({
+        let shape =
+          CDF.order({xs: [|0., 1., 2., 4.|], ys: [|0.0, 1.0, 2.0, 2.0|]});
+      });
+    test("with regular inputs", () => {
+      expect(Dist.integral()) |> toBe(6.)
+    });
+  });
+});
diff --git a/__tests__/Functions__Test.re b/__tests__/Functions__Test.re
new file mode 100644
index 00000000..5dda5e3d
--- /dev/null
+++ b/__tests__/Functions__Test.re
@@ -0,0 +1,92 @@
+open Jest;
+open Expect;
+
+exception ShapeWrong(string);
+describe("Functions", () => {
+  test("interpolate", () => {
+    let a = Functions.interpolate(10., 20., 1., 2., 15.);
+    let b = 1.5;
+    expect(a) |> toEqual(b);
+  });
+  test("range#1", () => {
+    expect(Functions.range(1., 5., 3)) |> toEqual([|1., 3., 5.|])
+  });
+  test("range#2", () => {
+    expect(Functions.range(1., 5., 5)) |> toEqual([|1., 2., 3., 4., 5.|])
+  });
+  test("range#3", () => {
+    expect(Functions.range(-10., 15., 2)) |> toEqual([|(-10.), 15.|])
+  });
+  test("range#4", () => {
+    expect(Functions.range(-10., 15., 3)) |> toEqual([|(-10.), 2.5, 15.|])
+  });
+  test("range#5", () => {
+    expect(Functions.range(-10.3, 17., 3))
+    |> toEqual([|(-10.3), 3.3499999999999996, 17.|])
+  });
+  test("range#6", () => {
+    expect(Functions.range(-10.3, 17., 5))
+    |> toEqual([|
+         (-10.3),
+         (-3.4750000000000005),
+         3.3499999999999996,
+         10.175,
+         17.0,
+       |])
+  });
+  test("range#7", () => {
+    expect(Functions.range(-10.3, 17.31, 3))
+    |> toEqual([|(-10.3), 3.504999999999999, 17.31|])
+  });
+  test("range#8", () => {
+    expect(Functions.range(1., 1., 3)) |> toEqual([|1., 1., 1.|])
+  });
+  test("mean#1", () => {
+    expect(Functions.mean([|1., 2., 3.|])) |> toEqual(2.)
+  });
+  test("mean#2", () => {
+    expect(Functions.mean([|1., 2., 3., (-2.)|])) |> toEqual(1.)
+  });
+  test("mean#3", () => {
+    expect(Functions.mean([|1., 2., 3., (-2.), (-10.)|])) |> toEqual(-1.2)
+  });
+  test("min#1", () => {
+    expect(Functions.min([|1., 2., 3.|])) |> toEqual(1.)
+  });
+  test("min#2", () => {
+    expect(Functions.min([|(-1.), (-2.), 0., 20.|])) |> toEqual(-2.)
+  });
+  test("min#3", () => {
+    expect(Functions.min([|(-1.), (-2.), 0., 20., (-2.2)|]))
+    |> toEqual(-2.2)
+  });
+  test("max#1", () => {
+    expect(Functions.max([|1., 2., 3.|])) |> toEqual(3.)
+  });
+  test("max#2", () => {
+    expect(Functions.max([|(-1.), (-2.), 0., 20.|])) |> toEqual(20.)
+  });
+  test("max#3", () => {
+    expect(Functions.max([|(-1.), (-2.), 0., (-2.2)|])) |> toEqual(0.)
+  });
+  test("random#1", () => {
+    expect(Functions.random(1, 5)) |> toBeLessThanOrEqual(5)
+  });
+  test("random#2", () => {
+    expect(Functions.random(1, 5)) |> toBeGreaterThanOrEqual(1)
+  });
+  test("up#1", () => {
+    expect(Functions.up(1, 5)) |> toEqual([|1., 2., 3., 4., 5.|])
+  });
+  test("up#2", () => {
+    expect(Functions.up(-1, 5))
+    |> toEqual([|(-1.), 0., 1., 2., 3., 4., 5.|])
+  });
+  test("down#1", () => {
+    expect(Functions.down(5, 1)) |> toEqual([|5., 4., 3., 2., 1.|])
+  });
+  test("down#2", () => {
+    expect(Functions.down(5, -1))
+    |> toEqual([|5., 4., 3., 2., 1., 0., (-1.)|])
+  });
+});
diff --git a/src/Index.bs.js b/src/Index.bs.js
deleted file mode 100644
index d28cff64..00000000
--- a/src/Index.bs.js
+++ /dev/null
@@ -1,11 +0,0 @@
-'use strict';
-
-var React = require("react");
-var ReactDOMRe = require("reason-react/src/ReactDOMRe.js");
-var App$ProbExample = require("./App.bs.js");
-
-((import('./styles/index.css')));
-
-ReactDOMRe.renderToElementWithId(React.createElement(App$ProbExample.make, { }), "app");
-
-/*  Not a pure module */
diff --git a/src/utility/CdfLibrary.js b/src/utility/CdfLibrary.js
index ffe63322..2e23da7e 100644
--- a/src/utility/CdfLibrary.js
+++ b/src/utility/CdfLibrary.js
@@ -1,174 +1,170 @@
 const {
-    Cdf,
-    Pdf,
-    ContinuousDistribution,
-    ContinuousDistributionCombination,
-    scoringFunctions,
-  } = require("@foretold/cdf/lib");
-  const _ = require("lodash");
-  
-  /**
-   *
-   * @param xs
-   * @param ys
-   * @returns {{ys: *, xs: *}}
-   */
-  function cdfToPdf({ xs, ys }) {
-    let cdf = new Cdf(xs, ys);
-    let pdf = cdf.toPdf();
-    return { xs: pdf.xs, ys: pdf.ys };
-  }
+  Cdf,
+  Pdf,
+  ContinuousDistribution,
+  ContinuousDistributionCombination,
+  scoringFunctions,
+} = require("@foretold/cdf/lib");
+const _ = require("lodash");
 
-  /**
-   *
-   * @param xs
-   * @param ys
-   * @returns {{ys: *, xs: *}}
-   */
-  function pdfToCdf({ xs, ys }) {
-    let cdf = new Pdf(xs, ys);
-    let pdf = cdf.toCdf();
-    return { xs: pdf.xs, ys: pdf.ys };
-  }
-  
-  /**
-   *
-   * @param sampleCount
-   * @param vars
-   * @returns {{ys: *, xs: *}}
-   */
-  function mean(sampleCount, vars) {
-    let cdfs = vars.map(r => new Cdf(r.xs, r.ys));
-    let comb = new ContinuousDistributionCombination(cdfs);
-    let newCdf = comb.combineYsWithMean(sampleCount);
-  
-    return { xs: newCdf.xs, ys: newCdf.ys };
-  }
-  
-  /**
-   *
-   * @param sampleCount
-   * @param predictionCdf
-   * @param resolutionCdf
-   */
-  function scoreNonMarketCdfCdf(sampleCount, predictionCdf, resolutionCdf, resolutionUniformAdditionWeight=0) {
-    let toCdf = (r) => (new Cdf(r.xs, r.ys));
-    let prediction = toCdf(predictionCdf);
-    if (_.isFinite(resolutionUniformAdditionWeight)){
-      prediction = prediction.combineWithUniformOfCdf(
-        {
-          cdf: toCdf(resolutionCdf),
-          uniformWeight: resolutionUniformAdditionWeight,
-          sampleCount
-        }
-      );
-    }
-  
-    return scoringFunctions.distributionInputDistributionOutputMarketless({
-      predictionCdf: prediction,
-      resultCdf: toCdf(resolutionCdf),
-      sampleCount,
-    });
-  }
-  
-  /**
-   *
-   * @param sampleCount
-   * @param cdf
-   */
-  function differentialEntropy(sampleCount, cdf) {
-    let toCdf = (r) => (new Cdf(r.xs, r.ys));
-  
-    return scoringFunctions.differentialEntropy({
-      cdf: toCdf(cdf),
-      sampleCount: sampleCount
-    });
-  }
-  
-  /**
-   *
-   * @param x
-   * @param xs
-   * @param ys
-   * @returns {number}
-   */
-  function findY(x, { xs, ys }) {
-    let cdf = new Cdf(xs, ys);
-    return cdf.findY(x);
-  }
+/**
+ *
+ * @param xs
+ * @param ys
+ * @returns {{ys: *, xs: *}}
+ */
+function cdfToPdf({ xs, ys }) {
+  let cdf = new Cdf(xs, ys);
+  let pdf = cdf.toPdf();
+  return { xs: pdf.xs, ys: pdf.ys };
+}
 
-  /**
-   *
-   * @param x
-   * @param xs
-   * @param ys
-   * @returns {number[]}
-   */
-  function convertToNewLength(n, { xs, ys }) {
-    let dist = new ContinuousDistribution(xs, ys);
-    return dist.convertToNewLength(n);
-  }
-  
-  /**
-   *
-   * @param y
-   * @param xs
-   * @param ys
-   * @returns {number}
-   */
-  function findX(y, { xs, ys }) {
-    let cdf = new Cdf(xs, ys);
-    return cdf.findX(y);
-  }
-  
-  /**
-   *
-   * @param xs
-   * @param ys
-   * @returns {number[]}
-   */
-  function integral({ xs, ys }) {
-    if (_.includes(ys, NaN)){
-      return NaN;
-    }
-    else if (_.includes(ys, Infinity) && _.includes(ys, -Infinity)){
-      return NaN;
-    }
-    else if (_.includes(ys, Infinity)){
-      return Infinity;
-    }
-    else if (_.includes(ys, -Infinity)){
-      return -Infinity;
-    }
-  
-    let integral = 0;
-    for (let i = 1; i < ys.length; i++) {
-      let thisY = ys[i];
-      let lastY = ys[i - 1];
-      let thisX = xs[i];
-      let lastX = xs[i - 1];
-  
-      if (
-        _.isFinite(thisY) && _.isFinite(lastY) &&
-        _.isFinite(thisX) && _.isFinite(lastX)
-      ) {
-        let sectionInterval = ((thisY + lastY) / 2) * (thisX - lastX);
-        integral = integral + sectionInterval;
+/**
+ *
+ * @param xs
+ * @param ys
+ * @returns {{ys: *, xs: *}}
+ */
+function pdfToCdf({ xs, ys }) {
+  let cdf = new Pdf(xs, ys);
+  let pdf = cdf.toCdf();
+  return { xs: pdf.xs, ys: pdf.ys };
+}
+
+/**
+ *
+ * @param sampleCount
+ * @param vars
+ * @returns {{ys: *, xs: *}}
+ */
+function mean(sampleCount, vars) {
+  let cdfs = vars.map(r => new Cdf(r.xs, r.ys));
+  let comb = new ContinuousDistributionCombination(cdfs);
+  let newCdf = comb.combineYsWithMean(sampleCount);
+
+  return { xs: newCdf.xs, ys: newCdf.ys };
+}
+
+/**
+ *
+ * @param sampleCount
+ * @param predictionCdf
+ * @param resolutionCdf
+ */
+function scoreNonMarketCdfCdf(sampleCount, predictionCdf, resolutionCdf, resolutionUniformAdditionWeight = 0) {
+  let toCdf = (r) => (new Cdf(r.xs, r.ys));
+  let prediction = toCdf(predictionCdf);
+  if (_.isFinite(resolutionUniformAdditionWeight)) {
+    prediction = prediction.combineWithUniformOfCdf(
+      {
+        cdf: toCdf(resolutionCdf),
+        uniformWeight: resolutionUniformAdditionWeight,
+        sampleCount
       }
-  
-    }
-    return integral;
+    );
   }
-  
-  module.exports = {
-    cdfToPdf,
-    pdfToCdf,
-    findY,
-    findX,
-    convertToNewLength,
-    mean,
-    scoreNonMarketCdfCdf,
-    differentialEntropy,
-    integral,
-  };
-  
\ No newline at end of file
+
+  return scoringFunctions.distributionInputDistributionOutputMarketless({
+    predictionCdf: prediction,
+    resultCdf: toCdf(resolutionCdf),
+    sampleCount,
+  });
+}
+
+/**
+ *
+ * @param sampleCount
+ * @param cdf
+ */
+function differentialEntropy(sampleCount, cdf) {
+  let toCdf = (r) => (new Cdf(r.xs, r.ys));
+
+  return scoringFunctions.differentialEntropy({
+    cdf: toCdf(cdf),
+    sampleCount: sampleCount
+  });
+}
+
+/**
+ *
+ * @param x
+ * @param xs
+ * @param ys
+ * @returns {number}
+ */
+function findY(x, { xs, ys }) {
+  let cdf = new Cdf(xs, ys);
+  return cdf.findY(x);
+}
+
+/**
+ *
+ * @param x
+ * @param xs
+ * @param ys
+ * @returns {number[]}
+ */
+function convertToNewLength(n, { xs, ys }) {
+  let dist = new ContinuousDistribution(xs, ys);
+  return dist.convertToNewLength(n);
+}
+
+/**
+ *
+ * @param y
+ * @param xs
+ * @param ys
+ * @returns {number}
+ */
+function findX(y, { xs, ys }) {
+  let cdf = new Cdf(xs, ys);
+  return cdf.findX(y);
+}
+
+/**
+ *
+ * @param xs
+ * @param ys
+ * @returns {number[]}
+ */
+function integral({ xs, ys }) {
+  if (_.includes(ys, NaN)) {
+    return NaN;
+  } else if (_.includes(ys, Infinity) && _.includes(ys, -Infinity)) {
+    return NaN;
+  } else if (_.includes(ys, Infinity)) {
+    return Infinity;
+  } else if (_.includes(ys, -Infinity)) {
+    return -Infinity;
+  }
+
+  let integral = 0;
+  for (let i = 1; i < ys.length; i++) {
+    let thisY = ys[i];
+    let lastY = ys[i - 1];
+    let thisX = xs[i];
+    let lastX = xs[i - 1];
+
+    if (
+      _.isFinite(thisY) && _.isFinite(lastY) &&
+      _.isFinite(thisX) && _.isFinite(lastX)
+    ) {
+      let sectionInterval = ((thisY + lastY) / 2) * (thisX - lastX);
+      integral = integral + sectionInterval;
+    }
+
+  }
+  return integral;
+}
+
+module.exports = {
+  cdfToPdf,
+  pdfToCdf,
+  findY,
+  findX,
+  convertToNewLength,
+  mean,
+  scoreNonMarketCdfCdf,
+  differentialEntropy,
+  integral,
+};
diff --git a/src/utility/lib/CDF.re b/src/utility/lib/CDF.re
new file mode 100644
index 00000000..cbfefa6c
--- /dev/null
+++ b/src/utility/lib/CDF.re
@@ -0,0 +1,107 @@
+module type Config = {let shape: DistTypes.xyShape;};
+
+exception ShapeWrong(string);
+
+let order = (shape: DistTypes.xyShape): DistTypes.xyShape => {
+  let xy =
+    shape.xs
+    |> Array.mapi((i, x) => [x, shape.ys |> Array.get(_, i)])
+    |> Belt.SortArray.stableSortBy(_, ([a, _], [b, _]) => a > b ? 1 : (-1));
+  {
+    xs: xy |> Array.map(([x, _]) => x),
+    ys: xy |> Array.map(([_, y]) => y),
+  };
+};
+
+module Make = (Config: Config) => {
+  let xs = Config.shape.xs;
+  let ys = Config.shape.ys;
+  let get = Array.get;
+  let len = Array.length;
+
+  let validateHasLength = (): bool => len(xs) > 0;
+  let validateSize = (): bool => len(xs) == len(ys);
+  if (!validateHasLength()) {
+    raise(ShapeWrong("You need at least one element."));
+  };
+  if (!validateSize()) {
+    raise(ShapeWrong("Arrays of \"xs\" and \"ys\" have different sizes."));
+  };
+  if (!Belt.SortArray.isSorted(xs, (a, b) => a > b ? 1 : (-1))) {
+    raise(ShapeWrong("Arrays of \"xs\" and \"ys\" have different sizes."));
+  };
+  let minX = () => get(xs, 0);
+  let maxX = () => get(xs, len(xs) - 1);
+  let minY = () => get(ys, 0);
+  let maxY = () => get(ys, len(ys) - 1);
+  let findY = (x: float): float => {
+    let firstHigherIndex = Belt.Array.getIndexBy(xs, e => e >= x);
+    switch (firstHigherIndex) {
+    | None => maxY()
+    | Some(0) => minY()
+    | Some(firstHigherIndex) =>
+      let lowerOrEqualIndex =
+        firstHigherIndex - 1 < 0 ? 0 : firstHigherIndex - 1;
+      let needsInterpolation = get(xs, lowerOrEqualIndex) != x;
+      if (needsInterpolation) {
+        Functions.interpolate(
+          get(xs, lowerOrEqualIndex),
+          get(xs, firstHigherIndex),
+          get(ys, lowerOrEqualIndex),
+          get(ys, firstHigherIndex),
+          x,
+        );
+      } else {
+        ys[lowerOrEqualIndex];
+      };
+    };
+  };
+  let findX = (y: float): float => {
+    let firstHigherIndex = Belt.Array.getIndexBy(ys, e => e >= y);
+    switch (firstHigherIndex) {
+    | None => maxX()
+    | Some(0) => minX()
+    | Some(firstHigherIndex) =>
+      let lowerOrEqualIndex =
+        firstHigherIndex - 1 < 0 ? 0 : firstHigherIndex - 1;
+      let needsInterpolation = get(ys, lowerOrEqualIndex) != y;
+      if (needsInterpolation) {
+        Functions.interpolate(
+          get(ys, lowerOrEqualIndex),
+          get(ys, firstHigherIndex),
+          get(xs, lowerOrEqualIndex),
+          get(xs, firstHigherIndex),
+          y,
+        );
+      } else {
+        xs[lowerOrEqualIndex];
+      };
+    };
+  };
+  let convertWithAlternativeXs = (newXs: array(float)): DistTypes.xyShape => {
+    let newYs = Belt.Array.map(newXs, findY);
+    {xs: newXs, ys: newYs};
+  };
+  let convertToNewLength = (newLength: int): DistTypes.xyShape => {
+    Functions.(
+      range(min(xs), max(xs), newLength) |> convertWithAlternativeXs
+    );
+  };
+  let sampleSingle = (): float => Js.Math.random() |> findY;
+  let sample = (size: int): array(float) =>
+    Belt.Array.makeBy(size, i => sampleSingle());
+  let integral = () => {
+    Belt.Array.reduceWithIndex(ys, 0., (integral, y, i) => {
+      switch (i) {
+      | 0 => integral
+      | _ =>
+        let thisY = y;
+        let lastY = get(ys, i - 1);
+        let thisX = get(xs, i);
+        let lastX = get(xs, i - 1);
+        let sectionInterval = (thisY +. lastY) /. 2. *. (thisX -. lastX);
+        integral +. sectionInterval;
+      }
+    });
+  };
+};
diff --git a/src/utility/lib/Functions.re b/src/utility/lib/Functions.re
new file mode 100644
index 00000000..3124c873
--- /dev/null
+++ b/src/utility/lib/Functions.re
@@ -0,0 +1,36 @@
+exception RangeWrong(string);
+
+let interpolate =
+    (xMin: float, xMax: float, yMin: float, yMax: float, xIntended: float)
+    : float => {
+  let minProportion = (xMax -. xIntended) /. (xMax -. xMin);
+  let maxProportion = (xIntended -. xMin) /. (xMax -. xMin);
+  yMin *. minProportion +. yMax *. maxProportion;
+};
+
+let sum = Belt.Array.reduce(_, 0., (i, j) => i +. j);
+let mean = a => sum(a) /. (Array.length(a) |> float_of_int);
+let min = a => Belt.Array.reduce(a, a[0], (i, j) => i < j ? i : j);
+let max = a => Belt.Array.reduce(a, a[0], (i, j) => i > j ? i : j);
+let up = (a, b) =>
+  Array.make(b - a + 1, a)
+  |> Array.mapi((i, c) => c + i)
+  |> Belt.Array.map(_, float_of_int);
+let down = (a, b) =>
+  Array.make(a - b + 1, a)
+  |> Array.mapi((i, c) => c - i)
+  |> Belt.Array.map(_, float_of_int);
+let range = (min: float, max: float, n: int): array(float) => {
+  switch (n) {
+  | 0 => [||]
+  | 1 => [|min|]
+  | 2 => [|min, max|]
+  | _ when min == max => Belt.Array.make(n, min)
+  | _ when n < 0 => raise(RangeWrong("n is less then zero"))
+  | _ when min > max => raise(RangeWrong("Min values is less then max"))
+  | _ =>
+    let diff = (max -. min) /. Belt.Float.fromInt(n - 1);
+    Belt.Array.makeBy(n, i => {min +. Belt.Float.fromInt(i) *. diff});
+  };
+};
+let random = Js.Math.random_int;