Also, an expression such as
    { KEYNAME => [ PRICE => 0, CODE => 'code value 1', LABEL => 'RED' ] }
suggests you may be mistaking an array element for part of a hash key/value pair. The  => (fat arrow) operator is just a fancy comma (see Comma Operator), it does nothing | nothing in and of itself to form key/value pairs. The expression above is equivalent to
    { KEYNAME => [ 'PRICE', 0, 'CODE', 'code value 1', 'LABEL', 'RED' ] }
(update: in which an anonymous array is initialized with a set of unrelated, i.e., unpaired, elements).