Add fromNonEmpty and oneOf operations

Author: garyb

bower.json

@@ -1,18 +1,14 @@
 {
   "name": "purescript-nonempty",
-  "version": "1.0.0",
-  "moduleType": [
-    "node"
-  ],
   "ignore": [
     "**/.*",
     "node_modules",
     "bower_components",
     "output"
   ],
-  "repository": {                                                          
-    "type": "git",                                                         
-    "url": "git://github.com/paf31/purescript-nonempty.git"            
+  "repository": {
+    "type": "git",
+    "url": "git://github.com/paf31/purescript-nonempty.git"
   },
   "dependencies": {
     "purescript-console": "^0.1.0",

docs/Data/NonEmpty.md

@@ -53,7 +53,7 @@ Fold a non-empty structure, collecting results using a binary operation.
 foldMap1 :: forall f a s. (Semigroup s, Foldable f) => (a -> s) -> NonEmpty f a -> s
 ```
 
-Fold a non-empty structure, collecting results in a `Semigroup`. 
+Fold a non-empty structure, collecting results in a `Semigroup`.
 
 #### `fold1`
 
@@ -63,4 +63,16 @@ fold1 :: forall f s. (Semigroup s, Foldable f) => NonEmpty f s -> s
 
 Fold a non-empty structure.
 
+#### `fromNonEmpty`
+
+``` purescript
+fromNonEmpty :: forall f a r. (a -> f a -> r) -> NonEmpty f a -> r
+```
+
+#### `oneOf`
+
+``` purescript
+oneOf :: forall f a. (Alternative f) => NonEmpty f a -> f a
+```
+
 

src/Data/NonEmpty.purs

@@ -1,18 +1,23 @@
 -- | This module defines a generic non-empty data structure, which adds an additional
 -- | element to any container type.
 
-module Data.NonEmpty 
+module Data.NonEmpty
   ( NonEmpty(..)
   , (:|)
   , foldl1
   , foldMap1
   , fold1
+  , fromNonEmpty
+  , oneOf
   ) where
 
 import Prelude
 
-import Data.Foldable
-import Data.Traversable
+import Control.Alternative (Alternative)
+import Control.Alt ((<|>))
+
+import Data.Foldable (Foldable, foldl, foldr, foldMap)
+import Data.Traversable (Traversable, traverse, sequence)
 
 -- | A non-empty container of elements of type a.
 -- |
@@ -34,34 +39,40 @@ infix 5 :|
 foldl1 :: forall f a s. (Foldable f) => (a -> a -> a) -> NonEmpty f a -> a
 foldl1 f (NonEmpty a fa) = foldl f a fa
 
--- | Fold a non-empty structure, collecting results in a `Semigroup`. 
+-- | Fold a non-empty structure, collecting results in a `Semigroup`.
 foldMap1 :: forall f a s. (Semigroup s, Foldable f) => (a -> s) -> NonEmpty f a -> s
 foldMap1 f (NonEmpty a fa) = foldl (\s a1 -> s <> f a1) (f a) fa
 
 -- | Fold a non-empty structure.
 fold1 :: forall f s. (Semigroup s, Foldable f) => NonEmpty f s -> s
 fold1 = foldMap1 id
 
+fromNonEmpty :: forall f a r. (a -> f a -> r) -> NonEmpty f a -> r
+fromNonEmpty f (NonEmpty a fa) = a `f` fa
+
+oneOf :: forall f a. (Alternative f) => NonEmpty f a -> f a
+oneOf (NonEmpty a fa) = pure a <|> fa
+
 instance showNonEmpty :: (Show a, Show (f a)) => Show (NonEmpty f a) where
   show (NonEmpty a fa) = "(NonEmpty " ++ show a ++ " " ++ show fa ++ ")"
 
 instance eqNonEmpty :: (Eq a, Eq (f a)) => Eq (NonEmpty f a) where
   eq (NonEmpty a1 fa1) (NonEmpty a2 fa2) = a1 == a2 && fa1 == fa2
 
 instance ordNonEmpty :: (Ord a, Ord (f a)) => Ord (NonEmpty f a) where
-  compare (NonEmpty a1 fa1) (NonEmpty a2 fa2) = 
+  compare (NonEmpty a1 fa1) (NonEmpty a2 fa2) =
     case compare a1 a2 of
       EQ -> compare fa1 fa2
       other -> other
-      
+
 instance functorNonEmpty :: (Functor f) => Functor (NonEmpty f) where
   map f (NonEmpty a fa) = NonEmpty (f a) (map f fa)
-      
+
 instance foldableNonEmpty :: (Foldable f) => Foldable (NonEmpty f) where
   foldMap f (NonEmpty a fa) = f a <> foldMap f fa
   foldl f b (NonEmpty a fa) = foldl f (f b a) fa
   foldr f b (NonEmpty a fa) = f a (foldr f b fa)
-      
+
 instance traversableNonEmpty :: (Traversable f) => Traversable (NonEmpty f) where
   sequence (NonEmpty a fa) = NonEmpty <$> a <*> sequence fa
   traverse f (NonEmpty a fa) = NonEmpty <$> f a <*> traverse f fa