Add strict liftM

Author: phadej

Control/DeepSeq.hs

@@ -209,6 +209,13 @@ f $!! x = x `deepseq` f x
 force :: (NFData a) => a -> a
 force x = x `deepseq` x
 
+-- | Deeply strict version of 'Control.Applicative.<$>'.
+--
+-- @since 1.4.3.0
+(<$!!>) :: (Monad m, NFData b) => (a -> b) -> m a -> m b
+f <$!!> m = m >>= \x -> return $!! f x
+infixl 4 <$!!>
+
 -- | A class of types that can be fully evaluated.
 --
 -- @since 1.1.0.0