Add Alternative

Author: garyb

README.md

@@ -1,5 +1,27 @@
 # Module Documentation
 
+## Module Control.Alt
+
+### Type Classes
+
+    class (Functor f) <= Alt f where
+      (<|>) :: forall a. f a -> f a -> f a
+
+
+## Module Control.Alternative
+
+### Type Classes
+
+    class (Applicative f, Plus f) <= Alternative f where
+
+
+### Values
+
+    many :: forall f a. (Alternative f) => f a -> f [a]
+
+    some :: forall f a. (Alternative f) => f a -> f [a]
+
+
 ## Module Control.Apply
 
 ### Values
@@ -44,4 +66,12 @@
 
     unless :: forall m. (Monad m) => Boolean -> m Unit -> m Unit
 
-    when :: forall m. (Monad m) => Boolean -> m Unit -> m Unit
+    when :: forall m. (Monad m) => Boolean -> m Unit -> m Unit
+
+
+## Module Control.Plus
+
+### Type Classes
+
+    class (Alt f) <= Plus f where
+      empty :: forall a. f a

src/Control/Alt.purs

@@ -0,0 +1,6 @@
+module Control.Alt where
+
+infixl 3 <|>
+
+class (Functor f) <= Alt f where
+  (<|>) :: forall a. f a -> f a -> f a

src/Control/Alternative.purs

@@ -0,0 +1,12 @@
+module Control.Alternative where
+
+import Control.Alt
+import Control.Plus
+
+class (Applicative f, Plus f) <= Alternative f
+
+some :: forall f a. (Alternative f) => f a -> f [a]
+some v = (:) <$> v <*> many v
+
+many :: forall f a. (Alternative f) => f a -> f [a]
+many v = some v <|> pure []

src/Control/Plus.purs

@@ -0,0 +1,6 @@
+module Control.Plus where
+
+import Control.Alt
+
+class (Alt f) <= Plus f where
+  empty :: forall a. f a