This version is not any shorter than the Pascal version, but perhaps nearly as clear to someone that understands perl regexes.

use strict;
use warnings;
sub roll {
  my $point = int($_[0]);       # Just to be safe
  $point =~ /^(?:2|12)$/ && return 1/36;
  $point =~ /^(?:3|11)$/ && return 2/36;
  $point =~ /^(?:4|10)$/ && return 3/36;
  $point =~ /^(?:5|9)$/  && return 4/36;
  $point =~ /^(?:6|8)$/  && return 5/36;
  $point == 7 && return 6/36;
  warn "Invalid roll";
  return 0;
}
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