I'm guessing you need to change this part: 
[@{$d[$mapkey]}] if $d[$mapkey]->[1] =~ /$a[$_]/

[download]
That generates an undef when the match fails, and shallow-copies the arrayref $d[$mapkey] when the match succeeds. Sounds like you want something more like (untested): 
$d[$mapkey]->[1] =~ /$a[$_]/ ? [@{$d[$mapkey]}] : ()

[download]
to provide an empty list when the match fails. Using ?: in a map is a common idiom.

In reply to Re: map weirdness by ysth
in thread map weirdness by insaniac

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