[Haskell-cafe] why are implicit types different? (cleanup)

[S. Alexander Jacobson]

Ok, I'm not sure I understand the answer here, but how about a 
workaround.  My current code looks like this:

    tt = let ?withPassNet=wpn
             ?withPassNet'=wpn
             ?withPassNet''=wpn
         in passNet "passnet" ["user"] regImpl b

The type of wpn is:

    wpn :: Ev PassNet ev a -> Ev State ev a

The individual implicit parameters end up arriving with concrete 
values for a.  If I pass wpn to passNet explicitly, it also appears to 
get converted to a monotype on arrival at the inside of passNet.

So I guess the real question is, how do I pass a polytype* wpn?

-Alex-

* I would have thought the word was polymorphic, but you obvoiusly
   know.

______________________________________________________________
S. Alexander Jacobson tel:917-770-6565 http://alexjacobson.com



On Mon, 27 Nov 2006, Simon Peyton-Jones wrote:

> Implicit parameters have monotypes, not polytypes.  So ?f in g gets 
> type (Char->Char).  I rather doubt that something more general 
> (implicit parameters get polytypes) would work, given the implicit 
> "improvement" rules that implicit parameters require.
>
> Simon
>
> | -----Original Message-----
> | From: haskell-cafe-bounces at haskell.org [mailto:haskell-cafe-bounces at haskell.org] On Behalf Of S.
> | Alexander Jacobson
> | Sent: 21 November 2006 19:28
> | To: haskell-cafe at haskell.org
> | Subject: [Haskell-cafe] why are implicit types different? (cleanup)
> |
> |
> |
> | Why do g and g' have different types?
> |
> |    g x y = let ?f = \x-> x in ?f x ++ (show (?f y))
> |    g  :: [Char] -> [Char] -> [Char]
> |
> |    g' :: (Show t) => [Char] -> t -> [Char]
> |    g' x y = let f = \x-> x in f x ++ (show (f y))
> |
> | Is there a way I can use implicit types and let g be as general as g'?
> |
> | -Alex-
> |
> |
> | ______________________________________________________________
> | S. Alexander Jacobson tel:917-770-6565 http://alexjacobson.com
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