$ perl -MList::Util=first -le 'print first {lc eq "abc"}
    keys %{{ABC=>"ABC"}}'
abc
$ perl -MList::Util=first -le 'print first {uc eq "ABC"}
    keys %{{ABC=>"ABC"}}'
ABC
$ perl -MList::Util=first -le 'print first {/abc/i}
    keys %{{ABC=>"ABC"}}'
ABC
$ perl -MList::Util=first -le 'print first {lc eq "abc"}
    values %{{ABC=>"ABC"}}'
ABC
$ perl -MList::Util=first -le 'print first {lc eq "abc"}
    "ABC"'
ABC
$ perl -MList::Util=first -le 'print first {lc eq "abc"}
    values @{["ABC"]}'
ABC