Add a CLI

[simonw]

It would be useful if you could test MicroPython directly by treating micropython-wasm as a mini CLI.

[simonw]

Add a CLI to this, so you can run micropython-wasm -c "code goes here" to execute code directly or micropython-wasm to start a simple REPL or micropython-wasm name_of_file.py to load that file and execute it

[simonw]

I'll add command line arguments for setting available memory and fuel.

[simonw]

This is looking pretty good:

~/dev/micropython-wasm % uv run micropython-wasm -c 'print("hi")'
hi
~/dev/micropython-wasm % uv run micropython-wasm -c 'print("hi" * (344 ** 323424))'
micropython-wasm: guest trapped: error while executing at wasm backtrace:
    0:   0x5bea - <unknown>!<wasm function 138>
    1:   0x5e31 - <unknown>!<wasm function 141>
    2:  0x18ae1 - <unknown>!<wasm function 605>
    3:  0x10eeb - <unknown>!<wasm function 364>
    4:   0x90d6 - <unknown>!<wasm function 178>
    5:   0x8b0a - <unknown>!<wasm function 174>
    6:   0x84e4 - <unknown>!<wasm function 171>
    7:  0x38c2f - <unknown>!<wasm function 1268>
    8:  0x373ef - <unknown>!<wasm function 1264>
    9:  0x363aa - <unknown>!<wasm function 1263>
   10:  0x3cb5a - <unknown>!<wasm function 1320>
   11:   0x10c9 - <unknown>!<wasm function 27>

Caused by:
    wasm trap: all fuel consumed by WebAssembly

[simonw]

Built this in Codex GPT-5.5 high: https://gist.github.com/simonw/0380955996deb31557421635ef91c7bb

[simonw]

Wrote about this here: https://simonwillison.net/2026/Jun/6/micropython-in-a-sandbox/#try-it-yourself