5 ms·

https://github.com/HexHive/printbf https://github.com/HexHive/printbf well this is a brainfuck interpreter inside printf. I’m pretty sure there are plenty of c

by hahajk 6y ago

https://github.com/HexHive/printbf https://github.com/HexHive/printbf well this is a brainfuck interpreter inside printf. I’m pretty sure there are plenty of c-to-bf transpilers.

felixr 6y ago
This is by the same author as the ioccc entry and also one of authors of the paper showing the turing completeness of printf http://nebelwelt.net/publications/#15SEC http://nebelwelt.net/publications/#15SEC
- lifthrasiir 6y ago
  Ah, that explains everything. I have already seen this technique before and wondered why this entry has to be the best of show---I don't doubt it is worth the prize, just that it didn't sound very novel. But it all makes sense if the technique is not well known and authors tried to revitalize that.
klyrs 6y ago
That's fun, but esoteric languages in general and brainfuck in specific tend to lack things you'd want out of c: file system access, system calls, etc.
- archi42 6y ago
  Hm, I think you could add numeric syscalls, similar to what happens at the asm level. E.g. put the syscall id and some parameters on the "stack", then let the interpreter run the syscall with a new "instruction" e.g. '!'. This could even substitute '.' (putchar) and ',' (getchar), since these are very much just syscalls. So that would reduce the number of instructions by one (to 7). Oh, getting to 6 would also be fun: One might replace '[' and ']' with a conditional branch '?'. It just needs two parameters: condition and (signed) number of instructions to jump. Adds the bonus (much like normal asm) to write moch more ~~horribly abusive~~ flexible control flow than a structured "while(*ptr)".
  - jcande 6y ago
    That was my approach for an analogous program that uses memcpy instead of printf. I didn't go with the jit-style you describe, however. If you're curious here's how I setup the syscalls https://github.com/jcande/xenocryst/blob/master/src/gadgets.c#L815 https://github.com/jcande/xenocryst/blob/master/src/gadgets.... and here's the main loop https://github.com/jcande/xenocryst/blob/master/src/exec.c#L42 https://github.com/jcande/xenocryst/blob/master/src/exec.c#L...
  - enedil 6y ago
    It's already implemented: https://github.com/ajyoon/systemf https://github.com/ajyoon/systemf There is even an HTTP server built with it.
    - archi42 6y ago
      Why am I not even surprised...? I thought about writing a sentence about how (relatively) easy it would be to build a verified compiler (think CompCert-for-brainfuck); I'd guess the outcome is one of (a) "someone already did that as well, here is the link" or (b) "I spent the weekend with that, here is the project on github". The Internet is awesome, as are people :)

by hahajk 6y ago

https://github.com/HexHive/printbf https://github.com/HexHive/printbf well this is a brainfuck interpreter inside printf. I’m pretty sure there are plenty of c-to-bf transpilers.

felixr 6y ago

This is by the same author as the ioccc entry and also one of authors of the paper showing the turing completeness of printf http://nebelwelt.net/publications/#15SEC http://nebelwelt.net/publications/#15SEC

lifthrasiir 6y ago
Ah, that explains everything. I have already seen this technique before and wondered why this entry has to be the best of show---I don't doubt it is worth the prize, just that it didn't sound very novel. But it all makes sense if the technique is not well known and authors tried to revitalize that.

klyrs 6y ago

That's fun, but esoteric languages in general and brainfuck in specific tend to lack things you'd want out of c: file system access, system calls, etc.

archi42 6y ago
Hm, I think you could add numeric syscalls, similar to what happens at the asm level. E.g. put the syscall id and some parameters on the "stack", then let the interpreter run the syscall with a new "instruction" e.g. '!'. This could even substitute '.' (putchar) and ',' (getchar), since these are very much just syscalls. So that would reduce the number of instructions by one (to 7). Oh, getting to 6 would also be fun: One might replace '[' and ']' with a conditional branch '?'. It just needs two parameters: condition and (signed) number of instructions to jump. Adds the bonus (much like normal asm) to write moch more ~~horribly abusive~~ flexible control flow than a structured "while(*ptr)".
- jcande 6y ago
  That was my approach for an analogous program that uses memcpy instead of printf. I didn't go with the jit-style you describe, however. If you're curious here's how I setup the syscalls https://github.com/jcande/xenocryst/blob/master/src/gadgets.c#L815 https://github.com/jcande/xenocryst/blob/master/src/gadgets.... and here's the main loop https://github.com/jcande/xenocryst/blob/master/src/exec.c#L42 https://github.com/jcande/xenocryst/blob/master/src/exec.c#L...
- enedil 6y ago
  It's already implemented: https://github.com/ajyoon/systemf https://github.com/ajyoon/systemf There is even an HTTP server built with it.
  - archi42 6y ago
    Why am I not even surprised...? I thought about writing a sentence about how (relatively) easy it would be to build a verified compiler (think CompCert-for-brainfuck); I'd guess the outcome is one of (a) "someone already did that as well, here is the link" or (b) "I spent the weekend with that, here is the project on github". The Internet is awesome, as are people :)