Re:Lisp implementation in sed
by nate_martin on Friday June 27, 2014 @07:13PM
(#7956710)
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?
[ Parent
| on HN ]
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.
woah woah woah. we don't just throw around "waste of time" like that :)
I was wrong, obviously.
Becoming famous by wasting time is something to consider...
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).
> sed is provably Turing complete
This submission is in itself, an elegant proof that sed is Turing complete.
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.