Perhaps not originally, but now it is certainly a language design goal that the entire compilation pipeline can be parameterized and modified to allow for a hug

Perhaps not originally, but now it is certainly a language design goal that the entire compilation pipeline can be parameterized and modified to allow for a huge variety of custom transforms. AD is a subset of the transformations they are endeavouring to support. E.g. see https://github.com/JuliaLang/julia/pull/33955 https://github.com/JuliaLang/julia/pull/33955 Generally speaking, if there is any sort of code transformation pass that's needed for AD but not supported, you can expect people to be working to support either that specific transformation, or a generalization of the transformation. This has been a theme in the language development for years now.