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edjCase · Oct 23, 2023 · 5462b88 · 5462b88
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diff --git a/mops.toml b/mops.toml
@@ -1,11 +1,11 @@
 [dependencies]
-base = "0.8.7"
+base = "0.9.6"
 
 [package]
-name = ""
+name = "random"
 version = "0.1.0"
-description = "A library for "
-repository = "https://github.com/edjcase/motoko_"
+description = "A library for random helper funtions"
+repository = "https://github.com/edjcase/motoko_random"
 
 [dev-dependencies]
-test = "1.0.1"
+test = "1.0.1"
diff --git a/src/Library.mo b/src/Library.mo
diff --git a/src/RandomX.mo b/src/RandomX.mo
@@ -0,0 +1,97 @@
+import Random "mo:base/Random";
+import Debug "mo:base/Debug";
+import Int "mo:base/Int";
+import Nat8 "mo:base/Nat8";
+import Array "mo:base/Array";
+import Iter "mo:base/Iter";
+import Buffer "mo:base/Buffer";
+
+module Module {
+    public type RandomBinomialGenerator = {
+        binomial : (Nat8) -> ?Nat8;
+    };
+    public type RandomByteGenerator = {
+        byte : () -> ?Nat8;
+    };
+    public type RandomRangeGenerator = {
+        range : (Nat8) -> ?Nat;
+    };
+    public type RandomCoinGenerator = {
+        coin : () -> ?Bool;
+    };
+    public type RandomNumberGenerator = RandomBinomialGenerator and RandomByteGenerator and RandomRangeGenerator and RandomCoinGenerator;
+
+    public func fromSeed(seed : Blob) : FiniteX {
+        FiniteX(seed);
+    };
+
+    public func randomInt(random : RandomRangeGenerator, min : Int, max : Int) : ?Int {
+        if (min > max) {
+            Debug.trap("Min cannot be larger than max");
+        };
+        let range : Nat = Int.abs(max - min) + 1;
+
+        var bitsNeeded : Nat = 0;
+        var temp : Nat = range;
+        while (temp > 0) {
+            temp := temp / 2;
+            bitsNeeded += 1;
+        };
+
+        let ?randVal = random.range(Nat8.fromNat(bitsNeeded)) else return null;
+        let randInt = min + (randVal % range);
+        ?randInt;
+    };
+
+    public func randomNat(random : RandomRangeGenerator, min : Nat, max : Nat) : ?Nat {
+        let ?randInt = randomInt(random, min, max) else return null;
+        ?Int.abs(randInt);
+    };
+
+    public func shuffleArray<T>(random : RandomRangeGenerator, array : [T]) : ?[T] {
+        let arraySize = array.size();
+        if (arraySize == 0) {
+            return ?array;
+        };
+        let shuffledArray = Buffer.fromArray<T>(array);
+        Buffer.reverse(shuffledArray);
+        var i : Nat = arraySize;
+        for (item in shuffledArray.vals()) {
+            i -= 1;
+            let ?randIdx = randomNat(random, 0, i) else return null;
+            let temp = shuffledArray.get(i);
+            shuffledArray.put(i, shuffledArray.get(randIdx));
+            shuffledArray.put(randIdx, temp);
+        };
+        return ?Buffer.toArray(shuffledArray);
+    };
+
+    public class FiniteX(seed : Blob) {
+        let random : RandomNumberGenerator = Random.Finite(seed);
+
+        public func byte() : ?Nat8 {
+            random.byte();
+        };
+
+        public func bool() : ?Bool {
+            random.coin();
+        };
+
+        public func int(min : Int, max : Int) : ?Int {
+            Module.randomInt(random, min, max);
+        };
+
+        public func nat(min : Nat, max : Nat) : ?Nat {
+            Module.randomNat(random, min, max);
+        };
+
+        public func shuffleArray<T>(array : [T]) : ?[T] {
+            Module.shuffleArray<T>(random, array);
+        };
+
+        public func randomElement<T>(array : [T]) : ?T {
+            let ?i = nat(0, array.size() - 1) else return null;
+            ?array.get(i);
+        };
+    };
+};
diff --git a/test/Library.test.mo b/test/Library.test.mo
diff --git a/test/RandomX.test.mo b/test/RandomX.test.mo
@@ -0,0 +1,76 @@
+import Iter "mo:base/Iter";
+import { test } "mo:test";
+import Debug "mo:base/Debug";
+import Int "mo:base/Int";
+import RandomX "../src/RandomX";
+
+let assertEqualInt = func(expected : Int, actual : ?Int) : () {
+  if (actual != ?expected) {
+    switch (actual) {
+      case (null) Debug.trap("Expected " # Int.toText(expected) # ", but ran out of entropy.");
+      case (?i) Debug.trap("Expected " # Int.toText(expected) # ", got " # Int.toText(i));
+    };
+  };
+};
+
+test(
+  "int",
+  func() {
+    let testCases : [{ seed : Blob; expected : Int; min : Int; max : Int }] = [
+      {
+        seed = "\A1\B2\C3\D4\E5\F6\10\11\12\13\14\15\16\17\18\19\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27";
+        expected = 1;
+        min = 0;
+        max = 10;
+      },
+      {
+        seed = "\A1\B2\C8\D4\E5\F6\10\11\12\13\14\15\16\17\18\19\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27";
+        expected = -3;
+        min = -4;
+        max = 5;
+      },
+      {
+        seed = "\A1\B2\C8\D4\E5\F6\10\11\12\13\14\15\16\17\18\19\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27";
+        expected = 711156982585303;
+        min = -1;
+        max = 1_000_000_000_000_000;
+      },
+    ];
+    for (testCase in Iter.fromArray(testCases)) {
+      let rand = RandomX.fromSeed(testCase.seed);
+      let randInt = rand.int(testCase.min, testCase.max);
+      assertEqualInt(testCase.expected, randInt);
+    };
+  },
+);
+
+test(
+  "nat",
+  func() {
+    let testCases : [{ seed : Blob; expected : Nat; min : Nat; max : Nat }] = [
+      {
+        seed = "\A1\B2\C3\D4\E5\F6\10\11\12\13\14\15\16\17\18\19\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27";
+        expected = 1;
+        min = 0;
+        max = 10;
+      },
+      {
+        seed = "\A1\B2\C8\D4\E5\F6\10\11\12\13\14\15\16\17\18\19\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27";
+        expected = 2;
+        min = 1;
+        max = 5;
+      },
+      {
+        seed = "\A1\B2\C8\D4\E5\F6\10\11\12\13\14\15\16\17\18\19\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27\1A\1B\1C\1D\1E\1F\20\21\22\23\24\25\26\27";
+        expected = 711156982685303;
+        min = 99999;
+        max = 1_000_000_000_000_000;
+      },
+    ];
+    for (testCase in Iter.fromArray(testCases)) {
+      let rand = RandomX.fromSeed(testCase.seed);
+      let randInt = rand.nat(testCase.min, testCase.max);
+      assertEqualInt(testCase.expected, randInt);
+    };
+  },
+);