[haskell-cafe] Monad and kinds
catamorphism at gmail.com
Fri Sep 5 02:17:42 EDT 2008
On 9/4/08, John Dorsey <haskell at colquitt.org> wrote:
> I'm no master either, but I'd argue that if we promise new programmers
> that they don't need to care about strictness, we thereby ensure that
> default laziness is treacherous.
> A year or two ago, ISTR that *most* of the newbie-generated traffic in
> the cafe was about atrocious performance of naive programs due to
> strict/lazy concerns. I think it was scaring people away.
I think it's debatable what the various causality relationships might be here.
> Adding strictness can improve asymptotic space performance, as an example.
> Is there a reason to think this won't always be true? Honest question,
> since I don't know nearly enough about strictness analysis to guess
> how good it'll be some day.
Adding strictness can also worsen asymptotic space (and time)
performance. That's one reason why we use a lazy language at all.
Strictness analysis is an approximation to the problem of determining
what parts of a program can be evaluated strictly without changing
their meaning, because if we had a perfect solution to that problem,
we could solve the halting problem.
Tim Chevalier * http://cs.pdx.edu/~tjc * Often in error, never in doubt
"There are no difficult problems, just unfortunate notations." --
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