11–20 of 107 posts
isn't rust kind of a nonstarter for cfg representations which are irreducibly cyclic? yes, one can use the pointers are array-indices thing, but ..
The article has fair points, but after trying OCaml and Rust... I chose Rust. Without going into huge amounts of detail, a compiler is more than simply a parser/ast/code generator and there are other aspects to consider such as the richness of the ecosystem, editor support, etc. Also, I suspect the author is more familiar with OCaml than Rust as you wouldn't typically box everything but likely use an arena for the AS…
I've been seriously at it with Rust for about six months now and really loving it. What do you mean by "use an arena for the AST?" What is an arena in this context?
The article has fair points, but after trying OCaml and Rust... I chose Rust. Without going into huge amounts of detail, a compiler is more than simply a parser/ast/code generator and there are other aspects to consider such as the richness of the ecosystem, editor support, etc. Also, I suspect the author is more familiar with OCaml than Rust as you wouldn't typically box everything but likely use an arena for the AS…
Can you write an equivalent piece of code that shows why Rust wins here with more familiarity and leveraging the ecosystem? With compilers I don't think there is a huge amount of using the ecosystem. I think what TFA does is a good case study in trying to be objective: write it both ways and compare.
I don’t even like rust.
1) built in eval -- this allows you to transpile to the host language which is invaluable for writing small tests
2) multiline string syntax -- for evaling more than just one liners
3) built in associative and sequential arrays (for the ast)
4) first class closures
5) panic support (for aborting early from unimplemented use cases)
The AST can be represented as an associative array. Each element type can have a 'type' field and rather than pattern matching, you can use if/else. Performance doesn't really matter for the bootstrap compiler because it will only ever be run on relatively small input sets. To get started, you simply walk the ast to transpile to the host language. The snippet is then evaled in the host language to test functionality. Closures allow you to implement the visitor pattern for each ast node, which allows contextual information to be seamlessly interwoven amongst ast nodes during the analysis/transpilation steps.
Keeping all of this in mind, I have identified luajit as my personal favorite language for compiler development. It checks the boxes above, has excellent all around performance for a dynamic language (particularly when startup time is included -- js implementations may beat it on many benchmarks but almost always have slow start up time relative to luajit) and provides a best in class ffi for host system calls. You can run 5000+ line lua scripts faster than most compilers can compile hello, world.
The other reason I like lua(jit) is the minimalism. Once you master lua (which is possible because of its small size) it becomes very obvious that if you can implement something in lua, you can translate the lua implementation to essentially any other language. In this way, there is a sense in which writing a lua implementation becomes almost like a rosetta stone in which a translation can be produced for nearly any other language. With more powerful languages, it is hard to resist the temptation to utilized features that can't always be easily transported to another language. In other words, lua makes it easy to write portable code. This is true both in the sense that lua can be installed on practically any computer in at most a few minutes and in the sense that the underlying structure of a lua program that transcends the syntax of the language can be ported to another computing environment/language.
Another benefit of transpiling to lua is that your new language can easily inherit lua's best properties such as embeddability, fast start up time and cross platform support while removing undesirable features like global variables. Your language can then also be used to replace lua in programs like nginx, redis and neovim that have lua scripting engines. This of course extends to transpiling to any language, which again should be relatively easy if you have already transpiled to lua.
Why does it seem like I'm hearing about OCaml all the time now? It could just be frequency bias but it wasn't that long ago that I'd never heard of it and now it seems to be getting a lot of attention online.
In my opinion, OCaml would see even more widespread use if the documentation were improved. I find it a chore to figure out how to use OCaml well. I also would like to use third-party libraries like Jane Street's Base because they've put a lot of work into providing even more functionality in their standard library, but their documentation is absolutely atrocious (where it exists at all).
OCaml is a mature language but does not have a very supportive ecosystem. I'm hoping the renewed interest will prompt changes there.
The article has fair points, but after trying OCaml and Rust... I chose Rust. Without going into huge amounts of detail, a compiler is more than simply a parser/ast/code generator and there are other aspects to consider such as the richness of the ecosystem, editor support, etc. Also, I suspect the author is more familiar with OCaml than Rust as you wouldn't typically box everything but likely use an arena for the AS…
I've been seriously at it with Rust for about six months now and really loving it. What do you mean by "use an arena for the AST?" What is an arena in this context?
The article has fair points, but after trying OCaml and Rust... I chose Rust. Without going into huge amounts of detail, a compiler is more than simply a parser/ast/code generator and there are other aspects to consider such as the richness of the ecosystem, editor support, etc. Also, I suspect the author is more familiar with OCaml than Rust as you wouldn't typically box everything but likely use an arena for the AS…
I've been seriously at it with Rust for about six months now and really loving it. What do you mean by "use an arena for the AST?" What is an arena in this context?
Earlier quoted context omitted.
I've been seriously at it with Rust for about six months now and really loving it. What do you mean by "use an arena for the AST?" What is an arena in this context?
i assume they're talking about an Arena Allocator https://blog.logrocket.com/guide-using-arenas-rust/
Earlier quoted context omitted.
I've been seriously at it with Rust for about six months now and really loving it. What do you mean by "use an arena for the AST?" What is an arena in this context?
I believe it means flattening the AST, here is a nice blog post about this technique https://www.cs.cornell.edu/~asampson/blog/flattening.html
EDIT: this was a really interesting read!