What are the respective ecosystems of these languages like for ML/NLP stuff? From what I can tell, the one with the most mature/active ecosystem is Rust. There is both Candle, a PyTorch equivalent, and a lib that (per my understanding) seeks to be 1:1 with the HuggingFace Python Transformers library (https://github.com/guillaume-be/rust-bert).
Haskell has HaskTorch, and OCaml has some OCaml thing that for some reason invokes PyTorch under the hood instead of just interfacing with the C++ deps directly. But it looks like there isn't support for doing things like replicating the Transformers library, and similarly maybe not a lot of support for issues and needs I haven't even run into yet (?)