Re: props for Hugs over System FC

Anthony Clayden <[email protected]> Mon, 25 Mar 2019 18:45:52 +1300

Newsgroups	gmane.comp.lang.haskell.glasgow.user
Message-ID	<CAM7nRYTNTAmnh2Sjaf_BO5L2S0hB=1RSOC6f7uOYVJps=PgVMg@mail.gmail.com>

On Mon, Mar 25, 2019 at 6:24 PM Anthony Clayden <
[email protected]> wrote:

>    ...
>

Errk. pasted the wrong example. The code that works is

    class F a b | a -> b

    instance F Int Bool

    class D a where { op :: (F a b) => a -> b }

    instance (TypeCast Bool b') => D Int where { op _ = typeCast True }

That dangling `b'` in the constraint is weird. Anyhow: compiles in
Hugs, doesn't in GHC. Unless someone here can persuade it?

AntC

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