Hello perlancar,

Tangential observation:

push @ary, "foo" unless grep { $_ eq "foo" } @ary;
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I think either the any or the none function in the core List::Util module would be better than grep in this case:

push @ary, "foo" unless any { $_ eq "foo" } @ary;
# OR
push @ary, "foo" if    none { $_ eq "foo" } @ary;
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Not only are these clearer (since the reader doesn’t have to work out “what is grep returning here?”), but they’re also more efficient because — unlike grep — they short-circuit as soon as a match is found.

Hope that’s of interest,