[Haskell-cafe] context deduction in GHC

[Brandon Allbery]

On Tue, Sep 30, 2014 at 1:52 PM, Doug McIlroy <doug at cs.dartmouth.edu> wrote:

> Ghci complains, "Could not deduce (Show a) arising from
> the superclasses of an instance declaration from the
> context (Num a)". Yet Show is a superclass of Num.
> Hugs accepts the code.
>

Show used to be a superclass of Num. It's not in current ghc, and will
probably be removed from the next version of the language standard.

-- 
brandon s allbery kf8nh                               sine nomine associates
allbery.b at gmail.com                                  ballbery at sinenomine.net
unix, openafs, kerberos, infrastructure, xmonad        http://sinenomine.net
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