[Haskell-cafe] Re: Implementing fixed-sized vectors (using
alfonso.acosta at gmail.com
Fri Mar 14 12:46:48 EDT 2008
On Fri, Mar 14, 2008 at 5:30 PM, Wolfgang Jeltsch
<g9ks157k at acme.softbase.org> wrote:
> I have a feedback from my Grapefruit co-developer about those aliases in the
> type-level package. He told me that on his machine, building this package
> took about 15 minutes, obviously because the machine ran out of RAM. He also
> told me that the generated object code was very large, and that loading the
> documentation page generated by Haddock took very long.
Fair point, it akes quite some time in my machine too (not 15minutes though)
> And he made a very good point: Who needs aliases for *all* numbers until, say,
> 10000? Who needs to hard-code the vector length 8247 in his code?
If I remember correctly aliases are generated until decimal 5000,
which might me really long anyway.
> I think
> that in practice, you only need very few numbers hard-coded. So it might be
> better to export a function for letting the package user generate the
> necessary aliases himself.
> I even think that it is probably sensible to drop the alias thing completely,
> at least if you have vector lengths in mind. What vector lengths will appear
> as fixed in a real world program? 1000? I think, usually you have only
> sizes like 2 or 3 hard-coded, for vectors in the mathematical sense. And
> their representation is already very short: D2, D3, … Remember that computed
> numbers are not shown as aliases in error messages, only numbers that
> directly appear in your code.
> My co-author also mentioned that he doesn't see much use for octal and
> hexadecimal notation.
> So I propose to drop alias support from type-level or at least let the package
> user do the necessary generation.
I think that removing aliases completely is not a good idea. How about
generating much lower aliases for decimals (lets say until 1000),
droping the other bases, and exporting a function to extended the
alias range at will? (that function could perfectly include the other
bases as well). Something called extendAliases would do.
I don't have the time to work on it now, but if you send me a patch
I'd be happy to apply it. It should be something simple to do. All the
Template Haskell machinery is already coded.
> > […]
> Best wishes,
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