Lisp implementation in sed

https://github.com/shinh/sedlisp

by inglesp • 12 years ago

207 60 12 years ago

github.com

mseri• 12 years ago

Ahahah. Awesome. There is even an 'awk' version: https://github.com/darius/awklisp

abecedarius2• 12 years ago

I wrote that, and I gotta say sed is a much crazier target.

More sed fun: http://aurelio.net/projects/sedsokoban/

breadbox2• 12 years ago

Indeed. There are few wide-spread programming languages around any more that lack such things as, say, any form of arithmetic whatsoever.

mzs• 12 years ago

Kudos, there was also this one: http://www.cs.cmu.edu/afs/cs/Web/Groups/AI/lang/lisp/impl/aw... Possibly based on the same newsgroup post?

mtdewcmu9• 12 years ago

That's kind of funny, because awk is already a programming language.

bndr• 12 years ago

This is amazing. Just reading the code makes my head hurt, but you implemented a language with it.

lengads• 12 years ago

Here, for example, is the implementation of `atom` (I think):

  /(atom /{
    /\[\S\+\]/{
      s/.*/[]/
      bpop_context
    }
    s/.*/t/
    bpop_context
  }

sejje• 12 years ago

If this was (the only available) programming, I'd quit.

Kudos, I think, to the author. His pain tolerance exceeds mine by a vast amount.

mtdewcmu9• 12 years ago

The way you can nest conditions in sed, like /foo/ { /bar/x }, is pretty powerful, and I knew a good bit of sed before I realized you could do that. It's not readily obvious from the manual.

hobbyist• 12 years ago

The author has won an IOCCC contest. This would have just pricked him a bit.

nate_martin• 12 years ago

Would someone mind giving a quick explanation of how this works? I have only used sed to replace text in files and directories. How do people write interpreters and game loops with this unix utility?

mtdewcmu9• 12 years ago

With difficulty.

I started playing with the idea of making a programming language out of sed at one point, but then I decided that, even if I succeeded, it would be a waste of time.

I didn't take into account Hacker News.

catshirt4• 12 years ago

woah woah woah. we don't just throw around "waste of time" like that :)

nix1• 12 years ago

Becoming famous by wasting time is something to consider...

jes5199• 12 years ago

the sed language allows conditional jumps to labels. That makes it powerful enough to write programs in.

If you had to just write programs by running a series of sed substitution expressions to a file over and over, and not use conditionals... it might still be possible to program in. Much harder to think about, though.

rmorell• 12 years ago

sed is provably Turing complete: http://www.catonmat.net/blog/proof-that-sed-is-turing-comple... which means that it's effectively able to simulate any other Turing-complete language (provided enough processing power and memory).

bnegreve• 12 years ago

sed is provably Turing complete

This submission is in itself, an elegant proof that sed is Turing complete.

IvyMike• 12 years ago

Now you have three problems.

krapp2• 12 years ago

Oh come on. They took an unreadable language and implemented a slightly less unreadable language in it. That's at least two problems and one solution.

To what, I don't know.

catshirt4• 12 years ago

did I misinterpret or did you just call lisp "[nearly] unreadable"? all languages are unreadable for the uninitiated.

mtdewcmu9• 12 years ago

Having a Lisp will make it a little easier to write the Javascript interpreter. Baby steps.

justinator3• 12 years ago

Well, OK: I'm curious, can I use the sed to Perl utility, to then make a Lisp implementation in Perl?

justinator3• 12 years ago

Trying this myself, it returns an error:

    s2p: expression #1: extra characters after command (d)

Thankfully, I've never had the job of porting a sed script to Perl, so I'm not exactly sure what that's all about. The docs mention this error, but don't explain what it means,

http://perldoc.perl.org/s2p.html

justinator3• 12 years ago

Aaaaand, obviously Perl has CPAN, so there's really no need (except to be evil):

https://metacpan.org/pod/CljPerl

(there's a few, actually, because TIMTOWTDI!)

asgard1024• 12 years ago

Wouldn't the opposite - stream editor (programmable) in Lisp - be more useful?

aaronem• 12 years ago

Well, if you count Emacs in batch mode, such a thing already exists.

bane• 12 years ago

So I guess if all languages are eventually converging on Lisp, are all Lisps eventually converging on sed? Is sed the bottom turtle or are there more?

Lisp implementation in sed

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