Merge pull request #44 from i-am-tom/master

Add `extend` instance for `Array`
purescript · May 29, 2017 · efaccc9 · efaccc9
2 parents c393ee5 + e2ce8e0
commit efaccc9
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diff --git a/src/Control/Extend.js b/src/Control/Extend.js
@@ -0,0 +1,9 @@
+"use strict";
+
+exports.arrayExtend = function(f) {
+  return function(xs) {
+    return xs.map(function (_, i, xs) {
+      return f(xs.slice(i));
+    });
+  };
+};
diff --git a/src/Control/Extend.purs b/src/Control/Extend.purs
@@ -27,6 +27,11 @@ class Functor w <= Extend w where
 instance extendFn :: Semigroup w => Extend ((->) w) where
   extend f g w = f \w' -> g (w <> w')
 
+foreign import arrayExtend :: forall a b. (Array a -> b) -> Array a -> Array b
+
+instance extendArray :: Extend Array where
+  extend = arrayExtend
+
 infixr 1 extend as <<=
 
 -- | A version of `extend` with its arguments flipped.