[Haskell-beginners] Pipe and typeclasses

Karol Samborski edv.karol at gmail.com
Tue Jul 23 21:56:20 CEST 2013

2013/7/23 Emmanuel Surleau <emmanuel.surleau at gmail.com>

> 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:

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