package owi

owi

owi is an OCaml toolchain to work with WebAssembly. It provides an interpreter as an executable and a library.

Installation

owi can be installed with opam:

$ opam install owi

If you don't have opam, you can install it following the how to install opam guide.

If you can't or don't want to use opam, you can build the package with dune build -p owi @install but you'll first have to install the dependencies by yourself. You can find the list of dependencies in the dune-project file.

Quickstart

Given a file test/passing/quickstart.wast with the following content:

(module $quickstart
  (func $f
    i32.const 24
    i32.const 24
    i32.add
    drop
  )
  (start $f)
)

Running the executable interpreter is as simple as:

$ dune exec src/bin/owi.exe -- --debug test/passing/quickstart.wast
simplifying  ...
typechecking ...
linking      ...
interpreting ...
stack        : [  ]
running instr: call 0
calling func : func f
stack        : [  ]
running instr: i32.const 24
stack        : [ i32.const 24 ]
running instr: i32.const 24
stack        : [ i32.const 24 ; i32.const 24 ]
running instr: i32.add
stack        : [ i32.const 48 ]
running instr: drop
stack        : [  ]
stack        : [  ]

You can also pass the --script flag to run the file as a reference test suite script. This will allow you to add constructs like assertions and will also link the spectest module, which provides function for e.g. printing.

If you're interested in the library part of owi, here's how to get started:

# open Owi;;
# let filename = "test/passing/quickstart.wast";;
val filename : string = "test/passing/quickstart.wast"
# let script =
    match Parse.from_file ~filename with
    | Ok script -> script
    | Error e -> failwith e;;
val script : Types.script =
...
# let m =
    match script with
    | Module m :: _ -> m
    | _ -> failwith "expected a module first";;
val m : Types.module_ =
...
# let module_to_run, link_state =
    match Compile.until_link Link.empty_state m with
    | Ok v -> v
    | Error e -> failwith e;;
val module_to_run : Link.module_to_run =
...
val link_state : Link.state =
...
# let () =
    Log.debug_on := true;
    match Interpret.module_ module_to_run with
    | Ok () -> ()
    | Error e -> failwith e;;
interpreting ...
stack        : [  ]
running instr: call 0
calling func : func f
stack        : [  ]
running instr: i32.const 24
stack        : [ i32.const 24 ]
running instr: i32.const 24
stack        : [ i32.const 24 ; i32.const 24 ]
running instr: i32.add
stack        : [ i32.const 48 ]
running instr: drop
stack        : [  ]
stack        : [  ]

For more, have a look at the example folder, at the documentation or at the test suite.

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