[Issue 6788] std.range.pairwise

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=6788

--- Comment #11 from bearophile_hugs at eml.cc ---
(In reply to bearophile_hugs from comment #10)

>               .pairwise!2

pairwise takes only one argument sequence, so that comment was bad. The
template argument is used to denote how many items you want in your "pairs"
(where 2 is the default).

So:

[1, 2, 3, 4].pairwise
Or:
[1, 2, 3, 4].pairwise!2

should yield:

(1, 2)
(1, 3)
(1, 4)
(2, 3)
(2, 4)
(3, 4)


[1, 2, 3, 4].pairwise!3

should yield:

(1, 2, 3)
(1, 2, 4)
(1, 3, 4)
(2, 3, 4)


Like in this lower level code:

void main() {
    import std.stdio, std.range, std.algorithm;
    auto a = [1, 2, 3, 4];

    foreach (immutable i; 0 .. a.length)
        foreach (immutable j; i + 1 .. a.length)
            writefln("(%d, %d)", a[i], a[j]);

    writeln;

    foreach (immutable i; 0 .. a.length)
        foreach (immutable j; i + 1 .. a.length)
            foreach (immutable k; j + 1 .. a.length)
                writefln("(%d, %d, %d)", a[i], a[j], a[k]);
}

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