[Haskell-beginners] Pipe and typeclasses

Emmanuel Surleau emmanuel.surleau at gmail.com
Wed Jul 24 21:12:23 CEST 2013

Thanks! Actually, I read about them some time ago (last year?) but prompty
forgot again, it looks like.

On Tue, Jul 23, 2013 at 9:56 PM, Karol Samborski <edv.karol at gmail.com>wrote:

> 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:
> http://www.haskell.org/haskellwiki/Functional_dependencies
Thanks Karol! I actually read about the concept some months ago, but
apparently forgot about it again.


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