Stream: general

Topic: wepl (The WebAssembly REPL)

Ryan Levick (rylev) (Sep 13 2023 at 08:33):

Announcement: I have a POC for a new tool called wepl (The WebAssembly REPL).

This tool allows you to interact with WebAssembly components in a continuous and dynamic way. The following features are currently supported:

• Evaluate exported functions
• Listing the imports and exports
• "Dynamic linking" (i.e., specifying that another WebAssembly component's export should be used to satisfy your component's import)
• Basic component composition (e.g., you can compose WASI-Virt with your component)
• Variable assignment (i.e., you can use the output of one export as input to another)
• Basic type checking for somewhat decent error messages.

Here's what a session might look like:

$ wepl mycomponent.wasm
> .exports
uppercase_and_suffix: func(input: string) -> string
> uppercase_and_suffix
uppercase_and_suffix: func(input: string) -> string
> s = "hello"
s: string
> .link suffix my_suffixer.wasm
> uppercase_and_suffix(s)
"HELLO!!"

Some future features would likely include:

• Full support for the composition language that @Brian and @Peter Huene have been working on
• More ways to do "dynamic linking" - (e.g., perhaps being able to satisfy an import with a Python script)
• More inspection and metadata capabilities (i.e., be the interactive front-end for much wasm-tools functionality)
• Saving composed components back to disk

I think this could be really useful, but I'm not sure what others will think, so feedback is very much appreciated.

Last updated: Nov 22 2024 at 17:03 UTC