See http://hackage.haskell.org/trac/ghc/ticket/3292
Turns m a -> m (). Lets one call functions for their side-effects without
having to get rid of their return values with '>> return ()'. Very useful
in many contexts (parsing, IO etc.); particularly good for 'forkIO' and 'forM_',
as they demand return types of 'IO ()' though most interesting IO functions
return non-().
forever :: (Monad m) => m a -> m b
forever a = a >> forever a
+-- | @'void' value@ discards or ignores the result of evaluation, such as the return value of an 'IO' action.
+void :: Functor f => f a -> f ()
+void = fmap (const ())
+
-- -----------------------------------------------------------------------------
-- Other monad functions