4 ms·

Scm2wasm: A Scheme to WASM compiler in 600 lines of C, making use of WASM GC

189 points by todsacerdoti 1y ago

koolala 1y ago
Can it be used as a interpreter once compiled to not need a compiler?
- wk_end 1y ago
  Just eyeballing it really quickly, it doesn’t look like it’s got the built-ins you’d want to quickly built a REPL (i.e. read or eval). It’s not really Scheme, yet. It’s written in C, so you could compile that to wasm and then compile & run all inside the browser (I guess, assuming wasm is cool with that sort of thing, not a wasm guy here).
  - circuit10 1y ago
    You can do that kind of JIT code generation with WASM but you need to compile a separate module and load and link things up in JS (doable but not technically within pure WASM, so it won’t work in standalone runtimes)
- shakna 1y ago
  This isn't quite a standards conforming Scheme just yet. On the other hand, Hoot supports WASM-GC on release [0], and has had wasm support for a few years now. (Though Safari support has been a pain point - they've found a few bugs in WebKit's wasm support.) [0] https://spritely.institute/news/hoot-0-6-1-released.html https://spritely.institute/news/hoot-0-6-1-released.html
  - davexunit 1y ago
    Thankfully, Safari and iOS now have the necessary bug fixes to run wasm binaries generated by hoot without issue.
- kreelman 1y ago
  I couldn't find evidence of an interpreter on the scm2wasm github page, but I only did a shallow look. Hoot (uses Guile Scheme), mentioned above, has a working interpreter, to quote... "The toolchain is self-contained and even features a Wasm interpreter for testing Hoot binaries without leaving the Guile REPL."
sshine 1y ago
Related: Guile Hoot is a Scheme to Wasm compiler written in Scheme. https://spritely.institute/hoot/ https://spritely.institute/hoot/
- kreelman 1y ago
  Thanks for including this. Hoot looks fantastic. There's a side project, Goblins https://spritely.institute/goblins/ https://spritely.institute/goblins/ that does distributed development too. Great to see that people are still supporting Scheme tools. There's a lot of utility here, even if people (and job adds) go for the "latest" tools.
  - davexunit 1y ago
    Thanks! Goblins is actually our main project and Hoot is the side project so we can deploy it on the web. Scheme is a really nice language and when you add in some modern features you can do some pretty neat things!
marianoguerra 1y ago
In case you are interested I wrote a minimal OOP runtime in wasm-gc (using wasm text format) here: https://marianoguerra.org/posts/bootstrap-post-collapse-oop-technology-with-wasm-gc-part-2/ https://marianoguerra.org/posts/bootstrap-post-collapse-oop-... I also wrote a forth in wasm by hand here: https://github.com/marianoguerra/ricardo-forth https://github.com/marianoguerra/ricardo-forth And a wasm compiler that fits in a tweet: https://wasmgroundup.com/blog/wasm-compiler-in-a-tweet/ https://wasmgroundup.com/blog/wasm-compiler-in-a-tweet/ I'm also the co-author of a book that shows you how to write a compiler that targets wasm for a small languaje using js: https://wasmgroundup.com/ https://wasmgroundup.com/ Here's a direct link to the wasm text format for the OOP and forth implementations: - https://github.com/marianoguerra/mclulang/blob/main/wat/fatt.wat https://github.com/marianoguerra/mclulang/blob/main/wat/fatt... - https://github.com/marianoguerra/ricardo-forth/blob/master/src/first.wast https://github.com/marianoguerra/ricardo-forth/blob/master/s...
- RodgerTheGreat 1y ago
  The Birth & Death of JavaScript wasn't talking about WASM, it was talking about Asm.js, which crucially differs from WASM by being a backwards-compatible subset of JavaScript amenable to JIT compilation. The goals of these standards look similar if all you care about is transpiling c and running it on a browser, but Asm.js worked everywhere from day zero modulo performance; WASM continues to be a moving target.
  - bloppe 1y ago
    Wasm has long supported everything you could do with asm.js. But wasm is about much more than C to browser. That's why it's still evolving.
  - leptons 1y ago
    Asm.js runs on the main thread, WASM runs in its own thread.
    - alex7o 1y ago
      Not exactly true WASM compilcation is in a different thread, but the execution happens on the same thread as JS if you don't do any webworker stuff. Edit: https://apryse.com/blog/how-to-enable-webassembly-threads https://apryse.com/blog/how-to-enable-webassembly-threads
nakamoto_damacy 1y ago
With call/cc ??
- sanxiyn 1y ago
  No, but with tail call (using underlying WebAssembly tail call).
- i2talics 1y ago
  Nope. I was thinking about implementing call/cc; there is a neat trick involving first doing a CPS transformation to the source, then providing call/cc as a builtin function that more-or-less just grabs the continuation argument and returns it. This would slot pretty easily in between expansion and code gen and the code generator would remain mostly untouched.
- matheusmoreira 1y ago
  Is there a reason to implement this other than standards compliance? There are plenty of problems with it: https://okmij.org/ftp/continuations/against-callcc.html https://okmij.org/ftp/continuations/against-callcc.html People do not generally want to capture the entire continuation, they want delimiters. Delimited continuations are a superset of call/cc and vastly more useful, more performant and easier to understand. The call/cc interface is completely backwards as well. It's like throw/catch but the exception handler is specified by throw instead of catch. Totally mind bending and unintuitive. This continuation business is just resumable exceptions. Would have been a lot easier for people to understand and use had they just called it that. try: print(10 + throw("error")) catch error, continuation: continuation(10) # Makes throw return 10, prints 20
  - davexunit 1y ago
    Despite call/cc being generally understood as not good it's still something you would expect to work in a Scheme implementation. In the Scheme-on-Wasm implementation I work on we emulate call/cc in terms of delimited continuations. Passes r7rs benchmaks that make use of call/cc. Seems kind of backwards to call them resumable exceptions because delimited continuations are the primitive upon which an exception system can be built but yeah maybe it would make sense to programmers that already understand exceptions. I like the prompt metaphor, myself. https://www.gnu.org/software/guile/manual/html_node/Prompts.html https://www.gnu.org/software/guile/manual/html_node/Prompts....
spankalee 1y ago
Meta comment: I love that this is on a self-hosted forge. I'm hoping that AT protocol-based self-hosted forges let us have the independence of self-hosted but the networking and gamification of GitHub. Maybe something like Tangled will bring that, though I haven't looked too deeply.
- rirze 1y ago
  Not AT protocol based (I think) but have you looked at Radicle? https://radicle.xyz https://radicle.xyz
MangoToupe 1y ago
I like wasm, but the idea of running an app in the browser is a real bummer. What kind of native interpreters are there?
- soegaard 1y ago
  Node.
- RossBencina 1y ago
  https://wasmtime.dev/ https://wasmtime.dev/
lambdaone 1y ago
Wouldn't a Scheme to WASM compiler in Scheme make more sense, providing the capability to do something like Gerbil Scheme?

189 points by todsacerdoti 1y ago

koolala 1y ago

Can it be used as a interpreter once compiled to not need a compiler?

wk_end 1y ago
Just eyeballing it really quickly, it doesn’t look like it’s got the built-ins you’d want to quickly built a REPL (i.e. read or eval). It’s not really Scheme, yet. It’s written in C, so you could compile that to wasm and then compile & run all inside the browser (I guess, assuming wasm is cool with that sort of thing, not a wasm guy here).
- circuit10 1y ago
  You can do that kind of JIT code generation with WASM but you need to compile a separate module and load and link things up in JS (doable but not technically within pure WASM, so it won’t work in standalone runtimes)
shakna 1y ago
This isn't quite a standards conforming Scheme just yet. On the other hand, Hoot supports WASM-GC on release [0], and has had wasm support for a few years now. (Though Safari support has been a pain point - they've found a few bugs in WebKit's wasm support.) [0] https://spritely.institute/news/hoot-0-6-1-released.html https://spritely.institute/news/hoot-0-6-1-released.html
- davexunit 1y ago
  Thankfully, Safari and iOS now have the necessary bug fixes to run wasm binaries generated by hoot without issue.
kreelman 1y ago
I couldn't find evidence of an interpreter on the scm2wasm github page, but I only did a shallow look. Hoot (uses Guile Scheme), mentioned above, has a working interpreter, to quote... "The toolchain is self-contained and even features a Wasm interpreter for testing Hoot binaries without leaving the Guile REPL."

sshine 1y ago

Related: Guile Hoot is a Scheme to Wasm compiler written in Scheme. https://spritely.institute/hoot/ https://spritely.institute/hoot/

kreelman 1y ago
Thanks for including this. Hoot looks fantastic. There's a side project, Goblins https://spritely.institute/goblins/ https://spritely.institute/goblins/ that does distributed development too. Great to see that people are still supporting Scheme tools. There's a lot of utility here, even if people (and job adds) go for the "latest" tools.
- davexunit 1y ago
  Thanks! Goblins is actually our main project and Hoot is the side project so we can deploy it on the web. Scheme is a really nice language and when you add in some modern features you can do some pretty neat things!

marianoguerra 1y ago

In case you are interested I wrote a minimal OOP runtime in wasm-gc (using wasm text format) here: https://marianoguerra.org/posts/bootstrap-post-collapse-oop-technology-with-wasm-gc-part-2/ https://marianoguerra.org/posts/bootstrap-post-collapse-oop-... I also wrote a forth in wasm by hand here: https://github.com/marianoguerra/ricardo-forth https://github.com/marianoguerra/ricardo-forth And a wasm compiler that fits in a tweet: https://wasmgroundup.com/blog/wasm-compiler-in-a-tweet/ https://wasmgroundup.com/blog/wasm-compiler-in-a-tweet/ I'm also the co-author of a book that shows you how to write a compiler that targets wasm for a small languaje using js: https://wasmgroundup.com/ https://wasmgroundup.com/ Here's a direct link to the wasm text format for the OOP and forth implementations: - https://github.com/marianoguerra/mclulang/blob/main/wat/fatt.wat https://github.com/marianoguerra/mclulang/blob/main/wat/fatt... - https://github.com/marianoguerra/ricardo-forth/blob/master/src/first.wast https://github.com/marianoguerra/ricardo-forth/blob/master/s...

RodgerTheGreat 1y ago
The Birth & Death of JavaScript wasn't talking about WASM, it was talking about Asm.js, which crucially differs from WASM by being a backwards-compatible subset of JavaScript amenable to JIT compilation. The goals of these standards look similar if all you care about is transpiling c and running it on a browser, but Asm.js worked everywhere from day zero modulo performance; WASM continues to be a moving target.
- bloppe 1y ago
  Wasm has long supported everything you could do with asm.js. But wasm is about much more than C to browser. That's why it's still evolving.
- leptons 1y ago
  Asm.js runs on the main thread, WASM runs in its own thread.
  - alex7o 1y ago
    Not exactly true WASM compilcation is in a different thread, but the execution happens on the same thread as JS if you don't do any webworker stuff. Edit: https://apryse.com/blog/how-to-enable-webassembly-threads https://apryse.com/blog/how-to-enable-webassembly-threads

nakamoto_damacy 1y ago

With call/cc ??

sanxiyn 1y ago
No, but with tail call (using underlying WebAssembly tail call).
i2talics 1y ago
Nope. I was thinking about implementing call/cc; there is a neat trick involving first doing a CPS transformation to the source, then providing call/cc as a builtin function that more-or-less just grabs the continuation argument and returns it. This would slot pretty easily in between expansion and code gen and the code generator would remain mostly untouched.
matheusmoreira 1y ago
Is there a reason to implement this other than standards compliance? There are plenty of problems with it: https://okmij.org/ftp/continuations/against-callcc.html https://okmij.org/ftp/continuations/against-callcc.html People do not generally want to capture the entire continuation, they want delimiters. Delimited continuations are a superset of call/cc and vastly more useful, more performant and easier to understand. The call/cc interface is completely backwards as well. It's like throw/catch but the exception handler is specified by throw instead of catch. Totally mind bending and unintuitive. This continuation business is just resumable exceptions. Would have been a lot easier for people to understand and use had they just called it that. try: print(10 + throw("error")) catch error, continuation: continuation(10) # Makes throw return 10, prints 20
- davexunit 1y ago
  Despite call/cc being generally understood as not good it's still something you would expect to work in a Scheme implementation. In the Scheme-on-Wasm implementation I work on we emulate call/cc in terms of delimited continuations. Passes r7rs benchmaks that make use of call/cc. Seems kind of backwards to call them resumable exceptions because delimited continuations are the primitive upon which an exception system can be built but yeah maybe it would make sense to programmers that already understand exceptions. I like the prompt metaphor, myself. https://www.gnu.org/software/guile/manual/html_node/Prompts.html https://www.gnu.org/software/guile/manual/html_node/Prompts....

spankalee 1y ago

Meta comment: I love that this is on a self-hosted forge. I'm hoping that AT protocol-based self-hosted forges let us have the independence of self-hosted but the networking and gamification of GitHub. Maybe something like Tangled will bring that, though I haven't looked too deeply.

rirze 1y ago
Not AT protocol based (I think) but have you looked at Radicle? https://radicle.xyz https://radicle.xyz

MangoToupe 1y ago

I like wasm, but the idea of running an app in the browser is a real bummer. What kind of native interpreters are there?

soegaard 1y ago
Node.
RossBencina 1y ago
https://wasmtime.dev/ https://wasmtime.dev/

lambdaone 1y ago

Wouldn't a Scheme to WASM compiler in Scheme make more sense, providing the capability to do something like Gerbil Scheme?