kotlingrad VS tangent

and that there is a mature library for autodiff https://github.com/breandan/kotlingrad

Thank you so much for the detail explaination! This remind me of tangent, an abandoned (?) SCT built by google couple of years ago. https://github.com/google/tangent

No, autograd acts similarly to PyTorch in that it builds a tape that it reverses while PyTorch just comes with more optimized kernels (and kernels that act on GPUs). The AD that I was referencing was tangent (https://github.com/google/tangent). It was an interesting project but it's hard to see who the audience is. Generating Python source code makes things harder to analyze, and you cannot JIT compile the generated code unless you could JIT compile Python. So you might as well first trace to a JIT-compliable sublanguage and do the actions there, which is precisely what Jax does. In theory tangent is a bit more general, and maybe you could mix it with Numba, but then it's hard to justify. If it's more general then it's not for the standard ML community for the same reason as the Julia tools, but then it better do better than the Julia tools in the specific niche that they are targeting. Jax just makes much more sense for the people who were building it, it chose its niche very well.