David, I like the way you paint your bike sheds. Array.range() (or similarly functional but differently named) is definitely another one of those "oft-rerolled" solutions.
Rick On Sun, Jul 10, 2011 at 4:23 PM, David Herman <[email protected]> wrote: > > So from this viewpoint (and regarding that example with squares), it's > good to have also `Array.seq(from, to)` method (the name is taken from > Erlang, I just frequently uses lists:seq(from, to) there): > > <bikeshed>Array.range seems like an intuitive name as well.</bikeshed> > > > Array.seq(1, 5).map((x) -> x * x); [1, 4, 9, 16, 25] > > This pattern (integer range immediately followed by map) is so common that > many Schemes have a more general function that fuses the two traversals, > sometimes called build-list or list-tabulate: > > Array.build(n, f) ~~~ [f(0), ..., f(n-1)] > > 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". > > Dave > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss >
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