On Wed, Feb 20, 2002 at 01:15:36PM -0800, Simon Peyton-Jones wrote:
> Another possiblity would be to make the ConCls class look like this
> class ConCls c where
> name :: String
> arity :: Int
> ...etc...
>
> Now we'd have to give an explicit type argument at the call site:
>
> show {| Constr c t |} (Con x) = (name {| c |}) ++ show x
>
> I quite like the thought of being able to supply explicit type
> arguments....
> but I don't konw how to speak about the order of type parameters.
> What order does map takes its two type parameters in?
Sorry, this seems like a non-sequitur to me?
'map' has type '(a->b) -> [a] -> [b]'; supplying explicit type
parameters would mean giving values to 'a' and 'b'. If I wanted to
propose notation for this, I would suggest, e.g.,
(map :: (String -> Int) -> [String] -> [Int]) length ["Hello", "World"]
'name' (above) has type 'String'; the '{| c |}' is not providing a type
parameter in the same sense.
What am I missing?
Best,
Dylan
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