I personally believe that

@y = map { condition($_) ? $_ : () } @x;

[download]

is generally spelt

@y = grep { condition($_) } @x;

[download]

Of course, you have the condition reversed, but then a ! would do, and I doubt it would impose a considerable penalty in terms of efficience.

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In reply to Re^2: Subtracting Lists by blazar
in thread Subtracting Lists by JimSki

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