Stream: compiler development

Topic: What traits should glue types support?

Sven van Caem (Oct 14 2024 at 14:35):

Currently, RustGlue.roc only generates a derived Debug implementation for RocFunction types:

#[repr(C)]
#[derive(Debug)]
pub struct RocFunction_65 {
   closure_data: Vec<u8>,
}

Some thoughts on this:

• I believe Clone would be safe to implement and wouldn't hurt to include.
• An implementation for Debug, while it exists now, probably wouldn't be all that useful in its current state (printing out the raw closure capture bytes). I argue we should implement Debug manually, but have it print e.g: "<function>" like it does in the REPL so it won't stop users from viewing the rest of the contents of a data structure that also contains a function.

Sven van Caem (Oct 14 2024 at 14:43):

Relatedly, generated record types currently derive PartialOrd and Ord. This allows a platform author to sort records by their fields, ranked by the order they appear in memory. Is this to allow for e.g: binary search on sorted lists of records? I thought I'd double check whether this might be a mistake, because outside of that one use-case, it seems like its behavior might be confusing to a platform author.

Sven van Caem (Oct 14 2024 at 14:51):

And if records implementing Ord _is_ desired behavior, should tag unions implement it too?

Brendan Hansknecht (Oct 14 2024 at 15:08):

Clone is not safe. At least not today.

Brendan Hansknecht (Oct 14 2024 at 15:09):

If you clone the raw closure capture, you may clone something refcounted. But you wouldn't increment the refcount. So roc will free it, but you will still have a reference to the old memory address

Brendan Hansknecht (Oct 14 2024 at 15:12):

As for ord....just a convenience if the platform happens to want it. Honestly, it may not really be useful. I'm not sure of a specific use case past sorting.

Brendan Hansknecht (Oct 14 2024 at 15:12):

I think tags and records should both be the same, but I'm not sure if that should be with or without ord

Sven van Caem (Oct 15 2024 at 06:53):

Gotcha, I think I'll leave it off for now then

Last updated: Jul 06 2025 at 12:14 UTC