%h = (
    key1 => 123,
    key2 => 'acb',
    key3 => 5,
);

# create second hash with only numeric values
%h_numbers = grep2 { looks_like_number($_[1]) } %h;

# prefix all values with "p"
%h_prefixed = map2 { ($_[0], "p".$_[1]) } %h;


@a = ( p1 => 111, p2 => 222, p3 => 333 );

# transforms array of ordered couples to array of single element hashes
@a_hashed = map2 { +{ $_[0] => $_[1] } } @a;