David Roundy
On Mon, Jul 30, 2007 at 11:47:46AM +0100, Jon Fairbairn wrote:
[snippage] This is all very horrid, but as far as I can tell what I was proposing wouldn't lead to such a mess, except possibly via defaulting, which, as the least important aspect of the idea could easily be abandoned.
What your suggestion would do would be to make the type inferred for every pattern-matched function polymorphic,
No it wouldn't. I reiterate: constructors would either belong to a class or to a datatype, so for constructors that belong to a datatype the situation would be exactly as before. It's unfortunate that when I wrote my example I assumed that everyone would understand that for some classes we would have defaults (because we already have this: the constructors for Integer effectively belong to a class and are defaulted to Integer). I'm now quite convinced that using defaults together with more general overloaded constructors would be a mistake, but that's all you've managed to convince me of! Yes, there is a problem that importing a class with a constructor into a scope that declares the same constructor as a data constructor would cause difficulties (namely the module would nolonger compile), but aren't they exactly the same difficulties as when the name in question is just a function name? -- Jón Fairbairn Jon.Fairbairn@cl.cam.ac.uk