tail-call

Co-author here. if you are interested in tail calls you just need to understand the call instruction which we cover in the book and then replace it with either: - return_call <funcidx>, the tail-call version of call - return_call_indirect <tableidx> <typeidx>, the tail-call version of call_indirect More info here: https://github.com/WebAssembly/tail-call/blob/main/proposals...

WASM does appear to have significant tailcall consideration: https://github.com/WebAssembly/tail-call/blob/main/proposals...

No it definitely has moved forward. See: https://news.ycombinator.com/item?id=32069418 https://github.com/WebAssembly/tail-call/issues/15#issuecomm...

Neat! This proposal caused me a lot of headaches, mechanizing its specification was the primary contribution of my Master's thesis a couple years ago[1]. I forgot until rereading it just now, but doing so caught a typo in the proposal specification[2], my extremely minor contribution to advancing WebAssembly. Glad to see it finally moving forward after stalling for so long! Excellent work! [1]: https://github.com/jacobmischka/uwm-masters-thesis/releases/... [2]: https://github.com/WebAssembly/tail-call/issues/10

It also uses experimental reference types (1). Tail calls at (2). The schism creator also provided feedback on the WA github at (3). 1. https://www.chromestatus.com/feature/5166497248837632 2. https://www.chromestatus.com/feature/5423405012615168 3. https://github.com/WebAssembly/tail-call/issues/5

> The WASM that everyone dreams about will be the same size, if it is supposed to match in features. The WASM I dream about (can't speak for anyone else) won't be a whole lot bigger than it is now [0], and I don't think anyone expects it to match the bigger VMs in features (the sheer number of features in the bigger VMs is part of the problem!). ---- [0]: It's already pretty great, IMO, and the additions I'd like to see - namely, support for multiple memories, and the handful of extra instructions necessary to support tail call optimization [0.1] and garbage collection [0.2] - ain't expected to be that huge of an addition in terms of instruction set bloat. I'm hopeful that they won't be especially complex to implement, either. [0.1]: https://github.com/WebAssembly/tail-call/blob/master/proposa... [0.2]: https://github.com/WebAssembly/gc/

"The tail calls proposal is also underway", but the repo hasn't had a commit in 5 months. https://github.com/WebAssembly/tail-call/blob/master/proposa...

The author takes a very pragmatic, rather than theoretic, approach to defining "functional programming." And it's the one I subscribe to: if we get more reliable software by calling programming patterns that provide many of the benefits of functional programming "functional programming," it is perhaps a moral obligation to loosen the definition. All that said, the main way in which Rust falls short is tail call optimization for recursive algorithms. Sadly, it's not likely to happen any time soon due to real technical challenges: https://github.com/rust-lang/rfcs/pull/1888#issuecomment-360... ... and also the fact that WebAssembly does not support tail calls either: https://github.com/WebAssembly/tail-call/blob/master/proposa...

I'm really looking forward to it. For others who are curious about it, here it is: https://github.com/WebAssembly/tail-call/blob/master/proposa...