Hi,
In some Haskell code I am writing at the moment I use a number of
multi-parameter classes, with various interrelated instances. One class
looks like
class Convert from to where conv :: from -> to
Everything works fine, but when I add functional dependencies, to reduce
the need for type signatures,
class Convert from to | from -> to where conv :: from -> to
GHC 4.08.1 fails with the message
basicTypes/Var.lhs:194: Non-exhaustive patterns in function readMutTyVar
(I also get messages like
zonkIdOcc: FunDep_a1sp
zonkIdOcc: FunDep_a1sj
zonkIdOcc: FunDep_a1sg
zonkIdOcc: FunDep_a1s8
zonkIdOcc: FunDep_a1sa
but these seem to be harmless.)
Is there a fix for this already, or should I prepare a more detailed bug
report?
Regards,
Thomas Hallgren
PS My code is accepted by Hugs...
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