$ perl -E 'say grep {++$i %2} <a b c d e f g>'
aceg
$ perl -E 'say grep {$i++ %2} <a b c d e f g>'
bdf

[download]

They only nasty thing about this solution is that it requires a variable (here $i) in the outer scope

A working Perl 6 solution: 

$ perl6 -e 'my @a = "a".."g"; say @a[0, *+2 ... +@a]'
aceg

[download]

An idiomatic Perl 6 solution (but not yet implemented in Rakudo): 

@a[0, *+2 ... *]

[download]

Another working Perl 6 solution, which is a variation of the grep theme but without the need of an external variable: 

say <a b c d e f g>.pairs.grep({.key !% 2})>>.value

[download]

(Updated: Added Perl 6 examples)

Perl 6 - links to (nearly) everything that is Perl 6.

In reply to Re: alternate array elements by moritz
in thread alternate array elements by Anonymous Monk

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