Yet another Hacker News

14 points epestr 12 hours ago 3 comments

throwaway99e2 11 hours ago | parent

Isn't this just a ray tracer in python/c that spits out brainfuck? By this logic gcc writes all my programs in assembly lol

Retro_Dev 50 minutes ago | parent

Well the proper analogy would be that you write your programs in assembly. I think the more impressive thing here isn't the ray tracer, but the C (or was it C++?) to brainf** transpiler. That would be equivalent to you writing both C code and the C compiler. Pretty impressive, but depending on the complexity of the program not as impressive as writing whatever it is in assembly directly. A raytracer would be PAIN to write directly in brainf** - I think I'd want to use fixed precision everywhere rather than emulated floating point. (on second glance, it does look like the author of the article is also using fixed precision arithmetic, but confusing the label for the layout of the number with the type of number representation itself?)

shoo 29 minutes ago | parent

brainfuck is unpleasant to write directly - e.g. the language doesn't have variables, so you need to manually do the bookkeeping of which memory offset is storing what 'variable'. & if you need to refactor your program slightly, in a way that changes the memory layout, maybe you need to manually rework the absolute & relative offsets. So I can appreciate why the author didn't roll up their sleeves to directly write BF - that's neither a productive nor interesting exercise.

Interesting to see how the author decomposed the problem:

- C raytracer https://github.com/mTvare6/rayfuck/blob/master/ray.c

~~ LLM refactor of the C code ~~>

- SSA-style C raytracer code https://github.com/mTvare6/rayfuck/blob/master/ray_ssa.c

~~ c2dsl.py helper script (compiler) ~~>

- DSL raytracer https://github.com/mTvare6/rayfuck/blob/master/ray.dsl

~~ dsl2bf.py helper script (another compiler) ~~>

BF raytracer https://github.com/mTvare6/rayfuck/blob/master/ray.bf (~22 mb of unreadable nonsense)

The dsl2bf compiler has a bunch of examples of implementing slightly higher level abstractions atop BF primitives. E.g. "go" to move the pointer to a different offset, destructive & non-destructive copies, all the way up to things like division -- BF only natively offers unary addition/subtraction.

If we have a read of the code of the final compiler, dsl2bf.py, the abstractions used in that code are relatively simple: global variables, local variables, lists, dicts, for loops, function definitions & function calls. It is feasible to implement a simple compiler like dsl2bf in BF itself, with sufficient head scratching. Again, quite unpleasant to try it directly in BF, but a next step could be to implement the dsl2bf compiler in the DSL itself - extending it if necessary, then compiling it with itself to produce a dsl2bf compiler implemented in BF.