[antlr-interest] A postmortem of my use of antler

[Loring Craymer]

----- Original Message ----
From: "siemsen at ucar.edu" <siemsen at ucar.edu>

There are many languages (most?) that can be translated without an AST phase.
If I don't need one, why bother?  Perhaps ASTs add some nice modularity, or
compartmentalize semantic errors or something?  I'm ready to be convinced, but I
want some value to compensate for the complexity they add to the translation process.


Trivial translations--A source to B source for languages in which language B can straightforwardly express the paradigms of language A--can be done without intermediate analysis.  Even there, an AST is helpful and aids maintainability.  Cross-paradigm translations--including code optimization--often require extensive multi-pass analysis.  For these, ASTs (and other data structures) are indispensable.  Also, if you use a parser with multiple backends, an AST makes it possible to re-use the same parser for the different backends without having a parser grammar for each.

That said, most ANTLR users never get beyond simple intra-paradigm translation problems or do analysis in the most brutal form with actions in a single pass processor.

--Loring 






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