[Haskell-beginners] What is wrong with my types signatures.

PICCA Frederic-Emmanuel frederic-emmanuel.picca at synchrotron-soleil.fr
Mon Jan 23 13:37:59 UTC 2017

Thanks a lot.

> Here's my guess.  I can't be sure without class instances and some
> function types that are not in code.

> sh' <- lift $ runMaybeT $ shapeND d :: Pipe a (XrdMeshFrame sh) IO (Maybe sh?)

> f <- lift $ runMaybeT $ rowND d (fromIndex sh' i') -- <- sh' is (Maybe
> sh), guessing that fromIndex does not take a Maybe.

This was the problem.


PS: The error message was right (as usual :), but I do not know why I was not able to found the cuprite.

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