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:
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, consult the opam file for build instructions.
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:
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 : [ ]” dir=”auto”>
| 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 : [ ]” dir=”auto”>
# open Owi;; # let filename = "test/passing/quickstart.wast";; val filename : string = "test/passing/quickstart.wast" # let script = match Parse.from_fil
