[Haskell-beginners] type of pattern matching

7 Jul 2010


      What if I want to check if a variable uses a particular constructor, but I 
don't want to unpack it. For example:

data Item = Note Int Float Rational [Int] [Float]
           | Dynamic Int

And I want to write

doSomething :: Maybe Result
doSomething item = case item of
   note@(Note _ _ _ _ _) -> Just $ process note
   _                     ->  Nothing

But I don't like writing "Note _ _ _ _ _"

Thanks,
Mike

[Haskell-beginners] type of pattern matching

Michael Mossey