BrowserUk:

Is this anything close? I'm not using map, and it's not pretty when dealing with undefined values, but it stops evaluating list arguments when it hits the match value. Perhaps it could be massaged into something you want.

$ cat 930256_a.pl
#!/usr/bin/perl
use strict;
use warnings;

#my @list = (5, undef, 1 .. 9);
my @list = (5, 1 .. 9);

sub xmap {
    my $match = shift;
    my $rc = shift;
    my @rv=();
    for (@_) {
        push @rv, &$rc($_);
        last if $_ eq $match;
    }
    return @rv;
}

print "list: ", join(", ", @list), ".\n";
print "xmap: ", join(", ", xmap(7, sub { $_*2 }, @list)),".\n";

$ perl 930256_a.pl
list: 5, 1, 2, 3, 4, 5, 6, 7, 8, 9.
xmap: 10, 2, 4, 6, 8, 10, 12, 14.
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...roboticus

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