Added fromInt

Author: reactormonk

CHANGELOG.md

@@ -7,6 +7,7 @@ Notable changes to this project are documented in this file. The format is based
 Breaking changes:
 
 New features:
+- `fromInt`
 
 Bugfixes:
 

src/Data/Ring/Extra.purs

@@ -0,0 +1,12 @@
+module Data.Ring.Extra where
+
+import Data.Ord ((>=))
+import Data.Ring (class Ring, one, negate)
+import Data.Monoid (power)
+import Data.Monoid.Additive (Additive(..))
+
+fromInt :: forall a. Ring a => Int -> a
+fromInt x =
+  if x >= 0
+    then (\(Additive i) -> i) (power (Additive one) x)
+    else negate (fromInt (negate x))