[haskell-cafe] Monad and kinds

Tim Chevalier 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."  --
Alfonso Gracia-Saz

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