my $word = 'sigma';

my $re = join '|' =>
    map join( '.*?' => map quotemeta,  @$_) =>
    map [ substr( $word, 0, $_), substr( $word, $_)] =>
    1 .. length( $word) - 1;

foreach my $text (
   'sigma',
   'stigma',
   'silly gamma',
   'magma',
) {
   print("$text ", ($text =~ $re ? "matches" : "doesn't match"), "\n");
}

##</code><code>##

map { [ $word =~ /(.{$_})(.*)/] } 1 .. length( $word) - 1;

##</code><code>##

map { ++ pos; [ split /\G/] } ( $word) x ( length( $word) - 1);