On 06 March 2005 08:49, Daniel Fischer wrote:
> while looking at Greg Buchholz's Joy-combinators (haskell-cafe,
> Friday), I discovered that the type inference of version 6.4.2005.022
> didn't work correctly. The code and comments indicating the
> incorrectly inferred types are attached (Joy2.hs).
> However, the implementation doesn't adhere strictly to the wrongly
> inferred types, e.g.
>
> *Joy2> linrec (id, (id, (id, ((pop ! lit True), (3,(2,1))))))
> (3,(2,1))
> *Joy2> :t pop ! lit True
> pop ! lit True :: (a, b) -> (Bool, b)
> *Joy2> :t linrec
> linrec :: (t -> t, (b -> b, (b -> t, (b -> (Bool, b), b)))) -> t,
>
> so it might well be that only the display of the inferred type is
> incorrect.
>
> As for the behaviour of :i,
> in version 6.2.2, default methods for classes were indicated, which I
> find a good idea, in 6.4.20050222 this is not so.
> Further, Hugs gives more instances, e.g. for
>> i Show,
> which may (or may not) be due to different exports from the Prelude,
> more serious is that version 6.4.20050222 doesn't give the contexts,
> which is bad if one defines an instance like
>
> instance (Ord a, Num a) => MyClass a where . . .,
>
> when
>> i MyClass gives
>
> instance MyClass a.
>
> Maybe, this has already been taken care of, I will today install
> version
> 6.4.20050304 and see.
I believe this is fixed; please test a later version and let us know.
Cheers,
Simon
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