51 lines
1.7 KiB
JavaScript
51 lines
1.7 KiB
JavaScript
(function () {
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// Right fold using final element as initial accumulator
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// (a -> a -> a) -> t a -> a
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function foldr1(f, lst) {
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return lst.length > 1 ? (
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f(lst[0], foldr1(f, lst.slice(1)))
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) : lst[0];
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}
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// function of arity 3 mapped over nth items of each of 3 lists
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// (a -> b -> c -> d) -> [a] -> [b] -> [c] -> [d]
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function zipWith3(f, xs, ys, zs) {
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return zs.length ? [f(xs[0], ys[0], zs[0])].concat(
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zipWith3(f, xs.slice(1), ys.slice(1), zs.slice(1))) : [];
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}
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// Evaluating from bottom up (right fold)
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// and with recursion left to right (head and first item of tail at each stage)
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return foldr1(
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function (xs, ys) {
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return zipWith3(
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function (x, y, z) {
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return x + (y < z ? z : y);
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},
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xs, ys, ys.slice(1) // item above, and larger of two below
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);
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}, [
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[55],
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[94, 48],
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[95, 30, 96],
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[77, 71, 26, 67],
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[97, 13, 76, 38, 45],
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[07, 36, 79, 16, 37, 68],
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[48, 07, 09, 18, 70, 26, 06],
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[18, 72, 79, 46, 59, 79, 29, 90],
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[20, 76, 87, 11, 32, 07, 07, 49, 18],
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[27, 83, 58, 35, 71, 11, 25, 57, 29, 85],
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[14, 64, 36, 96, 27, 11, 58, 56, 92, 18, 55],
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[02, 90, 03, 60, 48, 49, 41, 46, 33, 36, 47, 23],
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[92, 50, 48, 02, 36, 59, 42, 79, 72, 20, 82, 77, 42],
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[56, 78, 38, 80, 39, 75, 02, 71, 66, 66, 01, 03, 55, 72],
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[44, 25, 67, 84, 71, 67, 11, 61, 40, 57, 58, 89, 40, 56, 36],
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[85, 32, 25, 85, 57, 48, 84, 35, 47, 62, 17, 01, 01, 99, 89, 52],
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[06, 71, 28, 75, 94, 48, 37, 10, 23, 51, 06, 48, 53, 18, 74, 98, 15],
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[27, 02, 92, 23, 08, 71, 76, 84, 15, 52, 92, 63, 81, 10, 44, 10, 69, 93]
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]
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)[0];
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})();
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