I'm very interested in that. I was using zig for a while, and I wish I could build my own (simple) memory allocators for certain things in Haskell like that. I have a project where I want to be able to directly control the memory layout of the data structures but since that's just a tiny part of the whole program I don't want to build the whole thing in zig or something like C, I prefer Haskell for this specific purpose (it's a stream processing application with a small [code-wise, the data set can be huge] in-memory tree database which I want to be able to do the memory object allocation for myself).
Yeah you can do that. I'm actually working on a little library to do just that (control memory layout) although it's more focused on 0-copy FFI w/hsc2hs
You can also have the RTS manage the memory itself, but have complete access to a pointer to raw memory. That doesn't work if you have pointers in the raw memory ofc, but it is a nice option if that's not the case.
If you don't mind, can you send me your repos if it's public work? I'm interested in 0-copy stuff, too, the database I'm doing can benefit from 0-copy (again, a small part of the codebase but a big part of the technical challenge), and I'm seeing that linear types help a lot with that kind of thing from the reading I've done lately. I'm mostly a tinkerer and like to see what's the newest cool stuff people are making. My email is in my profile.
