[Haskell-cafe] Re: Type-level arithmetic

[Steve Schafer]

On Fri, 12 Oct 2007 13:25:28 -0700, you wrote:

>I'm not sure what sanity has to do with it. Presumably we all agree
>that it's a good idea for the compiler to know, at compile-time, that
>head is only applied to lists. Why not also have the compiler check
>that head is only applied to non-empty lists?

Again, that sort of practical application of type systems is not (as far
as I know) what this discussion is about. This discussion was spawned by
talk of using the type system to do truly bizarre things, such as solve
the Instant Insanity puzzle. A while back, Dan Piponi posed the question
of using the type system to solve one of the liar/truthteller logic
problems. And so on.

Steve Schafer
Fenestra Technologies Corp.
http://www.fenestra.com/