what about these? f,g :: Bool -> Int f x = 6 g x = x `seq` 6
As pointed out on #haskell by roconnor, we apparently don't care, this is a shame... We only care that x == y => f x == g y, and x == y can't tell if _|_ == _|_.
So the facts that
(1) f == g
(2) f undefined = 6
(3) g undefined = undefined
is not a problem?
/Jonas
2010/4/14 Thomas Davie
On 14 Apr 2010, at 09:12, Jonas Almström Duregård wrote:
f,g :: Bool -> Int
f x = 6
g x = 6
We can in Haskell compute that these two functions are equal, without solving the halting problem.
what about these? f,g :: Bool -> Int f x = 6 g x = x `seq` 6
As pointed out on #haskell by roconnor, we apparently don't care, this is a shame... We only care that x == y => f x == g y, and x == y can't tell if _|_ == _|_. It's a shame that we can't use this to tell if two functions are equally lazy (something I would consider part of the semantics of the function). Bob