Re: [Ocaml-lib-devel] Proposal: List.map_reduce

[<sp...@sc...>]

Jonathan Roewen wrote:
>> Do you think this should be added to ExtLib.ExtList, or is it too
>> "specialized"?
> 
> I don't think so. fold_reduce is a more general case of map_reduce.
> 

fold_reduce? Do you mean fold? If not, then what does the fold_reduce 
you're thinking of look like?

Anyway, I'm well aware that the reduce is a just special case of fold 
(where you assume that the folded function is "fully associative" by not 
specifying a fold "direction"). That's not the point, though.

The point is that combining the map with a reduce you get lighter syntax 
all the _usage sites_ where you can use the idiom and that it is 
slightly better efficiency-wise for huge lists. There is also precedent 
for this kind of thing -- see ExtList.filter_map.

Cheers,

-- 
Bardur Arantsson
<bar...@TH...>

Absolutely no one can sex a lobster without cutting it open.
                                       rusty @ http://kuro5hin.org