Re: [Haskell-beginners] Pipe and typeclasses

2013/7/23 Emmanuel Surleau

Hello,

I have seen from time to time the pipe symbol in type signatures, like so:

class Monad m => MonadReader r m | m -> r where

How should I interpret that ? Or more to the point, how does the compiler interpret it?

Hi Emmanuel! The pipe symbol is for a functional dependency: http://www.haskell.org/haskellwiki/Functional_dependencies Karol