Overloaded function and implicit parameter passing

Fergus Henderson fjh@cs.mu.oz.au
Tue, 24 Oct 2000 01:02:14 +1100


On 23-Oct-2000, Josť Romildo Malaquias <romildo@urano.iceb.ufop.br> wrote:
> ------------------------- cut here
> module Main where
> 
> class C a where
>     f :: (?env :: Integer) => a -> Integer
> 
> instance C Integer where
>     f x = ?env + x
> 
> main = putStrLn (show (f (45::Integer) with ?env = 100))
> ------------------------- cut here
...
> $ ghc -fglasgow-exts Test1.hs -o test1
> 
> Test1.hs:7:
>     Unbound implicit parameter `env_rJX :: Integer'
>     arising from use of `env_rJX' at Test1.hs:7
...
> Would anybody comment on what is going on with GHC?

That sure looks to me like a bug in GHC's support for implicit
parameter passing.

-- 
Fergus Henderson <fjh@cs.mu.oz.au>  |  "I have always known that the pursuit
                                    |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.