[erlang-questions] RFC: parse_trans for code generation

Ulf Wiger <>
Tue Aug 10 23:11:58 CEST 2010

Hi Vlad,

Thank you for that endorsement. :)

I agree with the usability issues, but still think
it's worthwhile to maintain a decent parse transform
library for Erlang proper. I will leave it to others
to explore the wonders of LFE.

Ulf W

Vlad Dumitrescu wrote:
> On Fri, Jul 2, 2010 at 12:44, Ulf Wiger <> wrote:
>> I realize that quite the minority of list readers take an
>> interest in parse transforms. Nevertheless, I thought I'd
>> highlight a small addition to the parse_trans project to
>> assist code generation.
>> http://github.com/esl/parse_trans
> Hi Ulf,
> I think it's a very nice piece of work. I had once started something
> similar, but didn't get even this far. I'm glad that you did :-)
> The problem as I see it is that even if this was unanimously voted as
> the greatest thing since sliced bread, it has some usability issues.
> Without a simpler syntax, it's simply not going to be used,
> unfortunately. Additionally, parse transforms (for all their coolness)
> have the disadvantage that they make the code very difficult to debug
> (except for the toy examples). So what is needed is extensible syntax
> and tooling support ("un-parse transforms").
> On the other hand, there is a place where this stuff is already
> usable, working (maybe not 100%, but close) and much more amenable to
> . I'm referring to LFE, of course. (Even the other beam-based
> languages can be considered here, but I haven't used tham) I'm
> guessing that the tooling support (with the debugger as the most
> important part) is lagging behind, but my guess is that it would be
> easier to develop than for Erlang-proper. The big question is when
> someone will get an itch severe enough to actually start scratching at
> it...
> best regards,
> Vlad

Ulf Wiger
CTO, Erlang Solutions Ltd, formerly Erlang Training & Consulting Ltd

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