Comment by asibahi

I dont really disagree with the main premise of the article, which is that WASM is not really a stack language, but this part just gave me pause:

> In textual Wasm, for example, they are instead represented in a LISP-like notation – not any less or more efficient

The Text format, at least when it comes to instructions, it 1 to 1 with the binary format. The LISP-like syntax is mainly just syntax sugar[1].

    ‘(’ plaininstr  instrs ‘)’ ≡  instrs plaininstr

So (in theory, as far as I understand it) you can just do `(local.get 2 local.get 0 local.get 1)` to mean `local.get 0 local.get 1 local.get 2`, and it works for (almost) any instruction.

Unfortunately, in my limited testing, tools like `wat2wasm` and Binaryen's `wasm-as` don't seem to adhere to (my perhaps faulty understanding of) the spec, and demand all instructions in a folded block be folded and have the "correct" amount of arguments, which makes Binaryen do weird things like

    (return
      (tuple.make     ;; Binaryen only pseudoinstruction
        (local.get 0) ;; or w/e expression
        (local.get 1) ;; or w/e expression
      )
    )

when this is perfectly valid

    local.get 0
    local.get 1
    return

tl;dr: the LISP syntax is just syntax sugar. The textual format is as "stack-like" as the binary format.

Edit: An example that is easily done with the stack syntax and not with lisp syntax is the following:

    call function_that_returns_multivalue
    local.set 2 ;; last return
    local.set 1 ;;
    local.set 0 ;; first return

In LISP syntax this would be

    (local.set 0
      (local.set 1
        (local.set 2
          (call function_that_returns_multivalue
            ( ;; whatever input paramters 
            )))))

I have not yet tried this with Binaryen but I doubt it flies.

[1]: https://webassembly.github.io/spec/core/text/instructions.ht...