[Haskell-cafe] MPTC and type classes issue (polymorphic '+')
mnislaih at gmail.com
Sat Apr 7 08:31:44 EDT 2007
> input2 =
> [ InputDecs [ inp "emaLength" TyNumber (20 + 40) ] ]
(untested). Imho the simple, dumb, best fix for this is to give a
explicit type to those values.
> input2 = [ InputDecs [ inp "emaLength" TyNumber ((20::Integer) +
(40::Integer)) ] ]
This is just one way to fix it. You could also try to improve your
instances or enable -foverlapping-instances. But in my experience
MPTC and overlapping instances, though powerful, can become very
confusing, very quickly.
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