> To me, in the WebASM world, transpiling to JavaScript is starting to seem a little old-fashioned.
It's behind a flag in a couple browsers. Even with a flag, if you're going to actually do anything with the DOM, you're going to be shipping a js support library and calling into it. Using something that works now has value, particularly when you could get wasm in the future off the same code if anybody writes an OCaml wasm backend.
> Presumably Rust (or Ocaml) compiled to WebASM will also have substantially improved performance compared to transpiled JavaScript
Bucklescript adds asm.js type hints (but not the use strings) to the js output and does a fair number of optimization passes. Aside from reducing parse time, going from its current output to wasm is unlikely to pick up much in the way of perf. I'm actually not even convinced that wasm is going to be that much faster for load+parse over an optimized js payload because asm.js/wasm have to ship the runtime (allocator, stdlib, etc) while js just has to ship the code.
> Readable JavaScript is not as important as long as we have source maps
I write Clojurescript full time, which has source map support. I completely disagree with this statement.
> Ocaml and Rust share a lot of heritage
Rust was bootstrapped off an OCaml compiler. I like Rust and advocate for it but bringing up another compile-to-js language, particularly one as nascent as Rust doesn't really have anything to do with the merits or drawbacks of Bucklescript.
It's behind a flag in a couple browsers. Even with a flag, if you're going to actually do anything with the DOM, you're going to be shipping a js support library and calling into it. Using something that works now has value, particularly when you could get wasm in the future off the same code if anybody writes an OCaml wasm backend.
> Presumably Rust (or Ocaml) compiled to WebASM will also have substantially improved performance compared to transpiled JavaScript
Bucklescript adds asm.js type hints (but not the use strings) to the js output and does a fair number of optimization passes. Aside from reducing parse time, going from its current output to wasm is unlikely to pick up much in the way of perf. I'm actually not even convinced that wasm is going to be that much faster for load+parse over an optimized js payload because asm.js/wasm have to ship the runtime (allocator, stdlib, etc) while js just has to ship the code.
> Readable JavaScript is not as important as long as we have source maps
I write Clojurescript full time, which has source map support. I completely disagree with this statement.
> Ocaml and Rust share a lot of heritage
Rust was bootstrapped off an OCaml compiler. I like Rust and advocate for it but bringing up another compile-to-js language, particularly one as nascent as Rust doesn't really have anything to do with the merits or drawbacks of Bucklescript.