pulling semiring in module

src/Semiring.hs

@@ -0,0 +1,19 @@
+{-# LANGUAGE Safe #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+
+module Semiring (
+  Semiring(..),
+  zero,
+) where
+
+import Data.Monoid
+
+-- | Alias for 'mempty'
+zero :: Monoid m => m
+zero = mempty
+
+class Monoid m => Semiring m where
+  {-# MINIMAL one, (<.>) #-}
+
+  one :: m
+  (<.>) :: m -> m -> m