higher-kind deriving ... or not

Tom Pledger Tom.Pledger@peace.com
Wed, 27 Feb 2002 09:09:18 +1300


Tom Pledger writes:
 | C T McBride writes:
 |  :
 |  | A little more tinkering, and it looks like it might be
 |  | 
 |  |   show :: Show (f (Wonky f)) => Wonky f -> String
 |  | 
 |  | Is this really the type of show?
 | 
 | That looks correct to me.

Well, after the first context reduction, anyway.  The type starts as

    Show a => a -> String

and after substitution becomes

    Show (Wonky f) => Wonky f -> String

and I'm not sure whether the first context reduction happens right
after that, or waits until f is substituted by something more concrete.