Just as a quick comment, Deparse is very useful when trying to determine what the parser is actually doing:

$ perl -MO=Deparse -e 'print cat dog'
print 'dog'->cat;
-e syntax OK
$ perl -MO=Deparse -e 'print reverse cat dog'
print reverse('dog'->cat);
-e syntax OK
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I'm going to ASSUME that 5.004 has this ability, but considering it's decades old, maybe not.