Question

I cannot for the life of me figure out why Alternative is left recursive. It really throws a wrench into my parser.

Alternative :: 
    [empty] 
    Alternative Term 

Here is a note in the semantics portion of the spec that is not exactly clear. Maybe the reasoning would be revealed once I understand this?

NOTE Consecutive Terms try to
simultaneously match consecutive
portions of the input String. If the
left Alternative, the right Term, and
the sequel of the regular expression
all have choice points, all choices in
the sequel are tried before moving on
to the next choice in the right Term,
and all choices in the right Term are
tried before moving on to the next
choice in the left Alternative.

What kind of parser can properly handle a left recursive grammar?

Answer 1

Because for certain types of parser left-recursion is much better (e.g. for yacc – see section 6.2 here for an explanation).

If it’s causing trouble for your particular parser, then by all means swap it over – it doesn’t affect the definition of the language in any way.