[Haskell-cafe] where to put handy functions?
stefanor at cox.net
Thu Aug 9 17:37:04 EDT 2007
On Thu, Aug 09, 2007 at 02:29:50PM -0700, Chad Scherrer wrote:
> Is there process for submitting functions for consideration for
> inclusion into future versions of the standard libraries? For example,
> I'd like to see this in Data.List:
> extract :: [Int] -> [a] -> [a]
> extract = f 0
> f _ _  = 
> f _  _ = 
> f k nss@(n:ns) (x:xs) = if n == k then x:f (k+1) ns xs
> else f (k+1) nss xs
> This behaves roughly as
> extract ns xs == map (xs !!) ns
> except that it's a lot more efficient, and it still works if ns or xs
> (but not both) are infinite. Oh, and "ns" are required to be ordered
> and non-negative.
> I'm guessing there are a lot of similarly simple handy functions, and
> I'm wondering if there's anything in place to avoid (1) reinventing
> the wheel, and (2) name clashes. Someone else may have written
> "extract" as well, meaning one of us wasted our time. And chances are,
> if they did, it has a different name, leading to forced qualified
> Finally, even if no one else is using it, it would be good to settle
> on reasonable names for things more easily. Is there a better name for
> this function? Is there a reason not to call it "extract"?
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