[antlr-interest] .g vs .g4

[Terence Parr]

Hi, Sam Harwell and I are talking about the file extension for new ANTLR 4. We think it makes good sense to use .g4 to distinguish the new grammars. They're mostly compatible except that there is no need for syntactic predicates and .g4 allows immediate left recursion. I think it will reduce confusion about what version of ANTLR is necessary to compile a grammar.

Ter