elixirscript · bryanjos · Aug 21, 2017 · Aug 21, 2017 · Aug 21, 2017
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## [unreleased]
+### Added
+- Reimplement `String.split_at/2` to make sure Unicode library isn't compiled
+
 ## [0.30.0] - 2017-08-15
 
 ### Added

diff --git a/lib/elixir_script/lib/functions.ex b/lib/elixir_script/lib/functions.ex
@@ -0,0 +1,6 @@
+defmodule ElixirScript.Core.Functions do
+  @moduledoc false
+  use ElixirScript.FFI, global: true
+
+  defexternal split_at(value, position)
+end
diff --git a/lib/elixir_script/lib/string.ex b/lib/elixir_script/lib/string.ex
@@ -198,4 +198,8 @@ defmodule ElixirScript.String do
   def valid?(str) do
     is_binary(str)
   end
+
+  def split_at(value, position) do
+    ElixirScript.Core.Functions.split_at(value, position)
+  end
 end
diff --git a/mix.exs b/mix.exs
@@ -4,7 +4,7 @@ defmodule ElixirScript.Mixfile do
   def project do
     [
       app: :elixir_script,
-      version: "0.30.0",
+      version: "0.31.0-dev",
       elixir: "~> 1.5",
       elixirc_paths: elixirc_paths(Mix.env),
       deps: deps(),

diff --git a/priv/build/iife/ElixirScript.Core.js b/priv/build/iife/ElixirScript.Core.js
diff --git a/src/javascript/lib/core/functions.js b/src/javascript/lib/core/functions.js
@@ -122,12 +122,40 @@ function trampoline(f) {
   return currentValue;
 }
 
+function split_at(value, position) {
+  if (position < 0) {
+    const newPosition = value.length + position;
+    if (newPosition < 0) {
+      return new Core.Tuple('', value);
+    }
+
+    return split_at(value, newPosition);
+  }
+
+  let first = '';
+  let second = '';
+  let index = 0;
+
+  for (const character of value) {
+    if (index < position) {
+      first = first + character;
+    } else {
+      second = second + character;
+    }
+
+    index = index + 1;
+  }
+
+  return new Core.Tuple(first, second);
+}
+
 export default {
   call_property,
   defprotocol,
   defimpl,
   build_namespace,
   map_to_object,
   trampoline,
-  Recurse
+  Recurse,
+  split_at
 };
diff --git a/src/javascript/tests/core/functions.spec.js b/src/javascript/tests/core/functions.spec.js
@@ -12,3 +12,15 @@ test('call_property', t => {
   t.is(Functions.call_property({ completed: false }, 'completed'), false);
   t.is(Functions.call_property({ id: 0 }, 'id'), 0);
 });
+
+test('split_at', t => {
+  t.deepEqual(Functions.split_at('sweetelixir', 5).values, ['sweet', 'elixir']);
+  t.deepEqual(Functions.split_at('sweetelixir', -6).values, [
+    'sweet',
+    'elixir'
+  ]);
+  t.deepEqual(Functions.split_at('abc', 0).values, ['', 'abc']);
+  t.deepEqual(Functions.split_at('abc', 1000).values, ['abc', '']);
+  t.deepEqual(Functions.split_at('abc', -1000).values, ['', 'abc']);
+  t.deepEqual(Functions.split_at('😀abélkm', 4).values, ['😀abé', 'lkm']);
+});