perl -MO=Deparse -e 'sub f {warn join "\n",@_,"",""};%a=("a",1,"b",2); print "ok" if f $a{a} && 5+f $a{b}'
# print 'ok' if f $a{'a'} && 5 + f($a{'b'});
# output 2 6 (* with sub f ($), it's 1 2)

perl -MO=Deparse -e 'sub f {warn join "\n",@_,"",""};%a=("a",1,"b",2); print "ok" if f($a{a} && 5+f $a{b})'
# print 'ok' if f $a{'a'} && 5 + f($a{'b'});
# output 5 2

perl -MO=Deparse -e 'sub f {warn join "\n",@_,"",""};%a=("a",1,"b",2); print "ok" if f($a{a} && 5)+f $a{b}'
# print 'ok' if f($a{'a'} && 5) + f($a{'b'});

perl -e 'sub f {warn join "\n",@_,"",""};%a=("a",1,"b",2); print "ok" if f($a{a}) && 5+f($a{b})'
# output 1 2

perl -e 'sub f {warn join "\n",@_,"",""};%a=("a",1,"b",2); print "ok" if f $a{a} and 5+f $a{b}'
# output 1 2