Array generation

Andreas Rossberg rossberg at
Mon Jul 11 04:03:15 PDT 2011

On 10 July 2011 22:23, David Herman <dherman at> wrote:
> Another common and useful fusion of two traversals that's in many Schemes is map-filter or filter-map:
>    a.filterMap(f) ~~~ [res for [i,x] of items(a) let (res = f(x, i)) if (res !== void 0)]
> I rather arbitrarily chose to accept both null and undefined here as way to say "no element" -- a reasonable alternative would be to accept *only* undefined as "no element".

\bikeshed{ The SML lib calls this one mapPartial, which I think is a
much better name. }


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