Please don't insert line numbers when posting code here. If people want to see line numbers, they can turn them on in their Display Settings.

Sub declarations like sub constructList($release, $daily_test) don't work, at least not in Perl 5 (but maybe you were just showing that as pseudocode).

'\n' does not result in a string containing a newline character, as \n is not special in single-quoted strings. But remember that the first argument of split is a regex, so it is probably clearer to write split /\n/ anyway.

== is not for comparing strings, only numbers (as a previous respondent said). Use eq for comparing strings.

You use [a] in a regex. That is a character class which matches the single letter a. I suspect that you meant the character class [a-z].

You assign $1 to $extracted, and then you use $1. You should use $extracted.

Use modules where possible. Don't reinvent the wheel, let alone the Space Shuttle.

I might rewrite your code as:

    my %add = (
      daily => \&addDaily,
      test  => \&addTest,
    );

    $add{$daily_or_test} or return; # should die instead?

    my @List;
    for ( split /\n/, $res->as_string )
    {
      if ( my( $extracted ) = /href="([a-z][^\/]*)/i )
      {
        $extracted =~ /win/i and
          $add{$daily_or_test}->( $extracted ) == 1 and
            push @List, $extracted;
      }
    }
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But since it looks like you're dealing with HTML, I'd use an HTML parser module, such as HTML::TreeBuilder.

Also, instead of passing in a string which symbolically indicates whether we're doing a daily or a test, you could pass in the function (by reference) directly:

    ref($daily_or_test) eq 'CODE' or die;
    . . .
          $daily_or_test->( $extracted )
    . . .
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