int[] arr = [1, 2, 3].join(0); // fail Expected: [1, 0, 2, 0, 3] This should work with any separator type if it's the element type of the range.
Changed summary. 'join' doesn't work in the way I thought it was, what I'm looking for is something different, an "interleave" type of function.
std.range.roundRobin( [1, 2, 3], 0.repeat(2) );
See https://github.com/dlang/phobos/pull/4251