[Haskell-beginners] How to interpret the definition of MonadState

djp at arqux.com djp at arqux.com
Tue Jun 7 16:59:44 CEST 2011

I am confused about the definition of MonadState. The opening line  
looks like this:

class Monad m => MonadState s m | m -> s where

It is the vertical bar | that confuses me. What does that mean? How  
would one read this line in "natural language", say English?


- J -

More information about the Beginners mailing list