case on monadic value

Question

Is there a way to perform a case on the value stored within a monad without having to bind a name to it?

i.e. instead of doing this:

c <- getChar
case         


        

Answer 1

No, not really, but you can move the case into another function and apply it to the result of a monadic action.

f x = case  x of ...

main = do
  f <$> getChar

Alternativly, the following is possible:

getChar >>= \x -> case x of ...

Answer 2

The proposal mentioned by FUZxxl was now implemented in GHC since 7.6.1, it's called LambdaCase.

Now you can do:

{-# LANGUAGE LambdaCase #-}
getChar >>= \case
   ...

Note the \ before the case keyword and the fact that there is no of in that case.

Answer 3

The answer is no. In Haskell 98, you can't use a case statement without using a name inside it. But there is a proposal for adding support for case-lambdas. The syntax they propose is the same you propose too.