[Haskell-cafe] Re: instance Eq (a -> b)
Thomas Davie
tom.davie at gmail.com
Wed Apr 14 04:15:00 EDT 2010
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
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