use strict;
use warnings;

my $value_buckets = {
    'first half'  => sub { print qq{first half!\n} },
    'second half' => sub { print qq{second half!\n} },
    'third half'  => sub { print qq{third half!\n} },
    'not found'   => sub { print qq{not found!\n} },
};

my $key = compute_key(42);

$value_buckets->{$key}->();

# just an example, could be anything to derive a hash
# key from $value
sub compute_key {
    my $value = shift;
    if ( $value > 0 and $value < 33 ) {
        return 'first half';
    }
    elsif ( $value >= 33 and $value <= 66 ) {
        return 'second half';
    }
    elsif ( $value >= 67 and $value <= 100 ) {
        return 'third half';
    }

    # last resort
    return 'not found';
}

##</code><code>##

# perl test.pl
second half!