Arc Forumnew | comments | leaders | submitlogin
2 points by akkartik 4005 days ago | link | parent

I have a greatly-enhanced respect for this perspective over the past month. Look at my travails over the past day trying to get optional, keyword and destructured args to play well together: https://github.com/akkartik/arc/compare/342ebf57a8...e347973.... Or my travails over the past month trying to build macex in wart in the presence of optional, keyword and destructured args AND quoted AND aliased params AND already-eval'd args[1] AND incompletely-eval'd args[2]: https://github.com/akkartik/wart/compare/30025ee25c...cabaa0.... Clearly there's some point at which I jump the shark :)

[1] related to apply for macros: http://arclanguage.org/item?id=16378

[2] related to partial eval: https://github.com/akkartik/wart/commit/8239ed9d21. I've been struggling intermittently with partial eval for two years now. This now year-long attempt might well be utterly useless.

---

Perhaps the easiest to understand and most serious extant example of the knots I end up tying myself into:

  arc> (iso :x :x)
  nil
This is because x is one of the params of iso. Even more serious, this happens even if you try to compare a variable that evaluates to :x. Or a variable that evaluates to a large structure containing :x somewhere in it. Ugh! The reason for this is that I'm extracting keyword args at function-call time inside each function. This:

  (def foo (x) x)
compiles down to something like:

  (define (foo allargs)
    (let ((keyword-args  (extract-keywords allargs '(x)))
      ..))
It took me three years to notice yesterday that I'm extracting keywords from post-evaluated arguments. Ugh! Urrrgggh!

Weird thing is, even wart has this problem. Even though I would superficially seem to be extracting keyword args pre-evaluation. I still need to debug this. Or perhaps I shouldn't debug this. Perhaps I should just throw up my hands and delete all my repos and become a hermit.