my @h = split /\s+/, 
         q[foo => zoo moo too bar => car far bar => zar tar qux => mux ];

print Dumper f(@h);

# output is:
$VAR1 = {
          'foo' => [
                     'zoo',
                     'moo',
                     'too'
                   ],
          'bar' => [
                     'car',
                     'far',
                     'zar',
                     'tar'
                   ],
          'qux' => [
                     'mux'
                   ]
        };