GenLex stream parsers too eager?

From: David McClain (
Date: Tue Jan 26 1999 - 18:33:46 MET

From: "David McClain" <>
To: "Liste CAML" <>
Subject: GenLex stream parsers too eager?
Date: Tue, 26 Jan 1999 10:33:46 -0700

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It appears that the Genlex derived parsers always eagerly tokenize =
negaitve integer and float constants. This causes incorrect behavior in =
closely spaced code (no-spaces):

    a-2*c --> parses as "a", "-2" ,"*", "c" instead of =

So instead of getting one expression tree, I get two, with the first =
containing only "a".
Also, if the operator were exponentiation instead of multiplication, the =
second tree would incorrectly compute a (possibly) complex valued =
expression instead of a simple negative of a real expression.

I have tried various workarounds, but they really obfuscate the original =
recursive descent structure of parsers.

Any suggestions? (Perhaps I should be using OCAMLLEX and OCAMLYACC =

David McClain
Sr. Scientist
Raytheon Missile Systems Co.
Tucson, AZ

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