🚀 go-pugleaf

Sorry about my last posting, the mailer mangled it.
In article <1992Jul27.083020.6061@st-andrews.ac.uk> ajtd@st-andrews.ac.uk (Antony J. T. Davie) writes:
>Julian Seward writes
>>I believe the Haskell committee should
>>consider the provision of two built-in functions:
>>
>>   hyperstrict, whnf :: Eq a => a -> b -> b
>>
>>both of which evaluate their first argument (fully or to whnf)
>>and return the second.  We can simulate this at the moment using
>>Haskell 1.2, but it might be more efficient if compilers could
>>regard these as primitive.
>
>Whether or not one agrees with the provision of these fns., why restrict
>them to Eq types? Certainly one can only easily simulate them if they
>operate on equality types, but that's no reason to restrict primitive
>versions of them so.
>
There should be some suitable restriction on the values that allow
whnf.  E.g.
	whnf :: (WHNFable a) => a -> b -> b
The function with type a->b->b that evaluates its first argument
and return the second is not definable within lambda calculus.
Having it enables you to distinguish between BOT and \x.BOT,
which are usually regarded as equal.  (whnf BOT 0 --> BOT, but
whnf (\x.BOT) 0 --> 0)

	-- Lennart

-- 

	-- Lennart Augustsson
[This signature is intentionally left blank.]