Add unsafe versions of charAt, charCodeAt

Author: garyb

Diff for: README.md

@@ -104,4 +104,13 @@
 
     split :: Regex -> String -> [String]
 
-    test :: Regex -> String -> Boolean
+    test :: Regex -> String -> Boolean
+
+
+## Module Data.String.Unsafe
+
+### Values
+
+    charAt :: Number -> String -> Char
+
+    charCodeAt :: Number -> String -> Number

Diff for: src/Data/String/Unsafe.purs

@@ -0,0 +1,24 @@
+module Data.String.Unsafe
+  ( charAt
+  , charCodeAt
+  ) where
+
+  import Data.Char
+
+  foreign import charCodeAt
+    """
+    function charCodeAt(i) {
+      return function(s) {
+        return s.charCodeAt(i);
+      };
+    }
+    """ :: Number -> String -> Number
+
+  foreign import charAt
+    """
+    function charAt(i) {
+      return function(s) {
+        return s.charAt(i);
+      };
+    }
+    """ :: Number -> String -> Char