On Thu, 2008-11-20 at 15:33 -0800, Don Stewart wrote:
duncan.coutts:
I don't think I'm just speaking for myself when I say that pseq is confusing and the docs similarly.
Given the type
a -> b -> b
we would assume that it is lazy in it's first arg and strict in the second. (Even in the presence of seq we know that it really really must be strict in it's second arg since it returns it or _|_ in which case it's still strict).
Of course we know of the seq primitive with this type that is strict in both. However we also now have pseq that has the _opposite_ "static" strictness to the original expected strictness.
Could you state "static" strictness as a StrictCheck property? I'm not quite sure what this distinction means, actually.
Note that you could make the actual and declared strictness match each other more closely by defining pseq to have the type: pseq :: a -> b -> (# b #) Now it's clear that it returns the second argument unevaluated. Of course that'd be a lot less convenient to use. Duncan