Conal Elliott wrote:
>The meaning of >"length getArgs" would then have to be a value whose type is the meaning >of Haskell's "Int", i.e. either bottom or a 32-bit integer. I'm >guessing that none of those 2^32+1 values is what you'd mean by "length >getArgs". On the other hand, the IO monad is a much roomier type.
I'm not strongly convinced by this argument. I don't think you can tell me which particular Char value you mean by the expression (maxBound :: Char) either, yet you probably wouldn't argue for changing maxBound's type. I think Jim's claim is that there's no clear dividing line between these cases, and I tend to agree. Even if you want to disallow explicit recompilation (and how do you define "compilation" denotationally?), an automatic rollout of a new version of Hugs could lead to successive invocations of a script using different values of (maxBound :: Char) (or, more plausibly, some constant defined in the library) without user intervention. How is this different from any other environmental change, such as a change in the program arguments? I think this is what Jim meant when he wrote
>It seems that, looking out at the world from main, the args passed to >main and the compilation happen at the same time (before, long long >ago). What motivation would we have for treating them differently?
-- Ben
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