[Haskell] Signature error because the order
Martijn van Steenbergen
martijn at van.steenbergen.nl
Thu Jan 14 07:24:16 EST 2010
Luis Cabellos wrote:
> But if I change the order of *Show* and *Num* in the signature of
> /prettyShow/ it works.
> It's a GHC problem? it's normal than signature is order-dependent?
I think this is on purpose. The error specifically says that the
contexts must be identical (rather than containing the same classes in
arbitrary). I suspect this is how Haskell98 has specified it.
If you enable the RelaxedPolyRec language extension, this restriction no
longer applies and your code compiles fine.
Hope this helps,
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