[Haskell-cafe] RE: why are implicit types different? (cleanup)
Benjamin Franksen
benjamin.franksen at bessy.de
Mon Nov 27 21:02:29 EST 2006
S. Alexander Jacobson wrote:
> 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?
Wrap it inside a newtype, maybe?
Ben
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