Ticket #125 (new defect)

Opened 4 years ago

Last modified 4 years ago

Missin MonadException instance for lazy StateT

Reported by: guest Owned by:
Priority: minor Milestone:
Version: Keywords:


System.Console.Haskeline.MonadException defines MonadException instances for the monad transformers in the transformers except for the lazy version of StateT.

I don't see a problem in adding an instance for both, but if it were, it should be more clearly explained in the haddocks that StateT refers to its *strict* version (right now, one needs to open the source to understand why no MonadException instance is found)

Change History

Changed 4 years ago by guest

I was about to report this, but hadn't seen that this was the correct formaulation of the problem. The package CPL fails to build with -fHaskeline because there's "No instance for (MonadException? (StateT UIState (InputT IO)))"; the solution there is to specify State.Strict explicitly, but it was quite a bit of trouble getting to this point...

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