10 Jul
2007
10 Jul
'07
4:10 p.m.
Stefan O'Rear wrote:
On Tue, Jul 10, 2007 at 08:59:16PM +0100, Andrew Coppin wrote:
I find myself wondering... A polymorphic type signature such as (a -> b) -> a -> b says "given that a implies b and a is true, b is true". But what does, say, "Maybe x -> x" say?
Given that x may or may not be true, x is definitely true.
Which, of course, is absurd.
...which, presumably, is because a (pure) function with that type might be able to fail?