Make sure /usr/lib/libffi.so is available.

uv sync
source .venv/bin/activate

# first, build the provided small c library
clang -shared -o mylib.so -fPIC examples/mylib.c

# build the example with mojo
mojo build -I src/ examples/ffi_repl.mojo

# then run it
./ffi_repl

Example usage (small repl to call C functions):

Enter lib path: ./mylib.so
> add 3 4
7
> multiply 5 1
5
> negate 4
-4
> multiply -5 9
-45
> var_add 3 2 2 2
6

Note that this is just a small example which only supports functions with int args. More types could be supported in the same way but for the REPL one would need a way to specify the types. Or a lexer could be added, that would be useful for strings and more types anyway.

Anther thing is that mojo build seems to not support static linking yet, thus the libffi symbols are also queried and called at runtime here.

To create a .mojopkg:

# create package
mojo package src/ffi -o ffi.mojopkg

This project is licensed under the MIT License - see the LICENSE file for details.