Using std.range.Lockstep as an input range

Question

Duplicating http://forum.dlang.org/thread/arlokcqodltcazdqqlby@forum.dlang.org to compare answer speed :)

I basically want to be able to do stuff like this:

auto result = map!( (a, b) => a+b )( lockstep(range1, range2) );

Are there any standard short ways to wrap an input range around struct with opApply (which Lockstep is)?

Also what about redesigning Lockstep as a proper range? I could do a pull request but not sure about current intentions.

Answer 1

And the prize goes to D.learn and Simen Kjaeraas :

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Use std.range.zip instead:

auto result = map!( (a, b) => a+b )( zip(range1, range2) );

The reason there are two ways is lockstep works better with foreach:

foreach (a, b; lockstep(A, B) ) {
    // Use a and b here.
}

Contrast with zip:

foreach (a; zip(A, B) ) {
  // Use a[0] and a[1] here.
}

There have been suggestions to better integrate tuples in the language, so in the future zip may have all the advantages of lockstep (and vice versa), but don't cross your fingers.