4 ms·

Automata via Macros (2006)

20 points by Jtsummers 2y ago

Jtsummers 2y ago
The paper itself is a PDF linked from that page, but the page also links to an earlier talk that may be of interest. Direct link to the PDF: https://cs.brown.edu/~sk/Publications/Papers/Published/sk-automata-macros/paper.pdf https://cs.brown.edu/~sk/Publications/Papers/Published/sk-au...
dang 2y ago
Related: Automata via Macros (Lisp) [pdf] - https://news.ycombinator.com/item?id=2723429 https://news.ycombinator.com/item?id=2723429 - July 2011 (3 comments)
ashton314 2y ago
This came up in https://news.ycombinator.com/item?id=40473381 https://news.ycombinator.com/item?id=40473381 I mentioned this paper and (stupidly) didn't include a direct link to it—definitely worthy of front-page HN attention. Another cross-ref: EdwardCoffin mentioned a (blog? chatroom?) post [1] by Guy Steele on why OO languages need tail calls; in that chat, Guy Steele references Automata via Macros. Nice to see a confluence of ideas. :) [1]: https://web.archive.org/web/20091206042608/http://projectfortress.sun.com/Projects/Community/blog/ObjectOrientedTailRecursion https://web.archive.org/web/20091206042608/http://projectfor...
aidenn0 2y ago
FWIW, similar macros in Common Lisp could be implemented using TAGBODY, which would not need tail-call elimination; tags have lexical scope and dynamic, so any functions defined within the tagbody can directly GO to any tag as long as the tagbody has not exited yet. It should be unsurprising that CL has construct(s) that allow this, given that the specification does not guarantee tail-call elimination.
- kazinator 2y ago
  In 2013, I made Common Lisp macros that provide something that looks like labels but is guaranteed tail recursive. https://www.kylheku.com/cgit/lisp-snippets/tree/tail-recursion.lisp https://www.kylheku.com/cgit/lisp-snippets/tree/tail-recursi... No docs or test suite, sorry. Just block comments. A trampoline based thing, deftail, is provided for global tail calls. In the paradigm implemented in this file, calls to tail functions are always tail calls, even if not in a tail context. If it looks like the return value of a tail call is used, too bad; that will never be reached.
mediumsmart 2y ago
Do kbd-macros in elisp for automation count?
- deleted 2y ago
  [deleted]

20 points by Jtsummers 2y ago

The paper itself is a PDF linked from that page, but the page also links to an earlier talk that may be of interest. Direct link to the PDF: https://cs.brown.edu/~sk/Publications/Papers/Published/sk-automata-macros/paper.pdf https://cs.brown.edu/~sk/Publications/Papers/Published/sk-au...

dang 2y ago

Related: Automata via Macros (Lisp) [pdf] - https://news.ycombinator.com/item?id=2723429 https://news.ycombinator.com/item?id=2723429 - July 2011 (3 comments)

ashton314 2y ago

This came up in https://news.ycombinator.com/item?id=40473381 https://news.ycombinator.com/item?id=40473381 I mentioned this paper and (stupidly) didn't include a direct link to it—definitely worthy of front-page HN attention. Another cross-ref: EdwardCoffin mentioned a (blog? chatroom?) post [1] by Guy Steele on why OO languages need tail calls; in that chat, Guy Steele references Automata via Macros. Nice to see a confluence of ideas. :) [1]: https://web.archive.org/web/20091206042608/http://projectfortress.sun.com/Projects/Community/blog/ObjectOrientedTailRecursion https://web.archive.org/web/20091206042608/http://projectfor...

aidenn0 2y ago

FWIW, similar macros in Common Lisp could be implemented using TAGBODY, which would not need tail-call elimination; tags have lexical scope and dynamic, so any functions defined within the tagbody can directly GO to any tag as long as the tagbody has not exited yet. It should be unsurprising that CL has construct(s) that allow this, given that the specification does not guarantee tail-call elimination.

kazinator 2y ago
In 2013, I made Common Lisp macros that provide something that looks like labels but is guaranteed tail recursive. https://www.kylheku.com/cgit/lisp-snippets/tree/tail-recursion.lisp https://www.kylheku.com/cgit/lisp-snippets/tree/tail-recursi... No docs or test suite, sorry. Just block comments. A trampoline based thing, deftail, is provided for global tail calls. In the paradigm implemented in this file, calls to tail functions are always tail calls, even if not in a tail context. If it looks like the return value of a tail call is used, too bad; that will never be reached.

mediumsmart 2y ago

Do kbd-macros in elisp for automation count?

deleted 2y ago
[deleted]