Merge pull request #117 from purescript/eq-ord-1

Add `Eq1` and `Ord1` classes

Author: garyb

src/Data/Eq.purs

@@ -1,4 +1,7 @@
-module Data.Eq (class Eq, eq, (==), notEq, (/=)) where
+module Data.Eq
+  ( class Eq, eq, (==), notEq, (/=)
+  , class Eq1, eq1, notEq1
+  ) where
 
 import Data.Unit (Unit)
 import Data.Void (Void)
@@ -54,3 +57,13 @@ instance eqArray :: Eq a => Eq (Array a) where
 foreign import refEq :: forall a. a -> a -> Boolean
 foreign import refIneq :: forall a. a -> a -> Boolean
 foreign import eqArrayImpl :: forall a. (a -> a -> Boolean) -> Array a -> Array a -> Boolean
+
+-- | The `Eq` type class represents type constructors with decidable equality.
+class Eq1 f where
+  eq1 :: forall a. Eq a => f a -> f a -> Boolean
+
+instance eq1Array :: Eq1 Array where
+  eq1 = eq
+
+notEq1 :: forall f a. (Eq1 f, Eq a) => f a -> f a -> Boolean
+notEq1 x y = (x `eq1` y) == false

src/Data/Ord.purs

@@ -1,5 +1,6 @@
 module Data.Ord
   ( class Ord, compare
+  , class Ord1, compare1
   , lessThan, (<)
   , lessThanOrEq, (<=)
   , greaterThan, (>)
@@ -13,7 +14,7 @@ module Data.Ord
   , module Data.Ordering
   ) where
 
-import Data.Eq (class Eq)
+import Data.Eq (class Eq, class Eq1)
 import Data.Function (on)
 import Data.Ord.Unsafe (unsafeCompare)
 import Data.Ordering (Ordering(..))
@@ -161,3 +162,10 @@ abs x = if x >= zero then x else negate x
 -- | any `x`, we should have `signum x * abs x == x`.
 signum :: forall a. (Ord a, Ring a) => a -> a
 signum x = if x >= zero then one else negate one
+
+-- | The `Ord1` type class represents totally ordered type constructors.
+class Eq1 f <= Ord1 f where
+  compare1 :: forall a. Ord a => f a -> f a -> Ordering
+
+instance ord1Array :: Ord1 Array where
+  compare1 = compare