[Haskell-cafe] Re: GHC predictability
andrewcoppin at btinternet.com
Wed May 14 14:29:02 EDT 2008
Richard A. O'Keefe wrote:
> On 14 May 2008, at 8:58 am, Andrew Coppin wrote:
>> What I'm trying to say [and saying very badly] is that Haskell is an
>> almost terrifyingly subtle language.
> Name me a useful programming language that isn't.
> Simply interchanging two for-loops, from
> for (i = 0; i < N; i++) for (j = 0; j < N; j++)
> to for (j = 0; j < N; j++) for (i = 0; i < N; i++)
> when marching over an array, can easily slow you down
> by nearly two orders of magnitude in C.
> [Hint: read "What every computer scientist needs to know
> about memory".]
OK, well *that* is news... :-o
I would suggest that for heap-allocated data that isn't an array, both
cases will be equally unperformant. I can't prove that though...
> "Unexpectedly slow" is better than "inexplicably buggy".
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