Access to foreign function interface (FFI)?

[eriksank]

Would it be possible to expose Rust's FFI functionality for invoking (over the C ABI) functions located in external libraries?

https://doc.rust-lang.org/nomicon/ffi.html

That would allow hush shell users to use a world of existing software.

[gahag]

Yes, I have plans on implementing it such that std.import would be able to import not only other Hush scripts, but native libraries too. It will take some work though, as I'll have to figure out how to safely share garbage collected objects through the FFI.

[eriksank]

I wonder if the current dichotomy between HushFun and RustFun in src/runtime/value/function.rs can also handle out of the box functions en provenance from the C ABI?

Since a C function is typified by barely much more than a void pointer, I somehow suspect that memory allocated by such C functions will be very difficult to deallocate by the Hush shell. If the user doesn't free it manually, I think that the process will simply leak memory.

Rust itself considers native C code to be fundamentally unsafe.

That point is certainly conceded, but we still need to somehow reuse external native code. For example, using GTK or QT will always potentially leak memory.

We would still benefit from these things being available, regardless of their unsafety ...

[gahag]

Makes sense to me. I guess we could add an ExternalFun struct, which would invoke a function through the FFI. Just need to figure out which useful parameters we should pass, and what to do with the return value. Sounds good to you?

[eriksank]

Yes!