10:26 <mayhem> hey

10:26 <mayhem> is here a better algorithm than the dominator based one for translating to SSA ?

12:35 <mayhem> anyone experienced in functionnal dataflow analysis ?

15:41 <haakonn> i have written a lexer/parser with the ocaml tools, but the error reporting in it is very poor (basically, the parser throws an exception, and my client code catches it and says "syntax error"). are there any examples of how to write better error reporting?

15:43 <monochrom> is there some information in the exception?

15:44 <haakonn> i don't think so, it's a Parsing.Parse_error

15:44 <haakonn> i should check the lib documentation though

15:45 <haakonn> "Raised when a parser encounters a syntax error. Can also be raised from the action part of a grammar rule, to initiate error recovery." is all it says

15:46 <haakonn> yeah, it's only string -> unit

15:48 <haakonn> section 12.4.4 of the ocaml manual talks about error recovery, but it's not very concrete

15:50 <monochrom> it assumes you know yacc.

15:50 <monochrom> it wants you to do it the yacc way.

15:51 <monochrom> I don't know yacc, so I can't be more concrete either. :)

15:51 <haakonn> me neither, unfortunately

15:58 <Smerdyakov> haakonn, I advise constructing a minimally sized input that you think should parse but doesn't.

15:58 <Smerdyakov> haakonn, then look at your rules and attempt to derive a parse tree for it by hand.

15:59 <Smerdyakov> haakonn, if you are sure there is a tree but can't find it, look at the filename.output file (if you are compiling filename.mly). It contains information on any shift/reduce or reduce/reduce conflicts

16:01 <haakonn> Smerdyakov: it can parse all legal programs fine, the problem is what it does with _illegal_ programs. specifically, the parser just throws a "dumb" exception with no useful information. i'd like the "client" code to find out what input file, what line number and what column number triggered the error, and report that.

16:03 <haakonn> i have a feeling Lexing.position could be useful in some way

16:04 <karryall> haakonn: ocamlyacc doesn't do this automatically, you have to keep track yourself of the current position in the input file (AFAIK)

16:05 <haakonn> karryall: doesn't it provide access to a Lexing.position? (i'm wading through the docs slowly)

16:07 <Smerdyakov> haakonn, not that I know of.

16:08 <haakonn> ok

16:14 <karryall> haakonn: in Lexing.position, only the character number is updated automatically. If you want lines number you have to do it yourself.

16:15 <haakonn> i see