Maybe there was some small miscommunication here – we are indeed working on "one AD to rule them all" (Capstan, [1]), but it won't go in the standard library as

Maybe there was some small miscommunication here – we are indeed working on "one AD to rule them all" (Capstan, [1]), but it won't go in the standard library as such (there's no need as it will be just as good as a package). That said, Capstan relies on very new compiler technology and still requires some deep changes there, so will only work on future Julia versions (which may be what he was referring to). Until then, Flux [2] has an AD that's well-suited to ML and works on current Julia versions. [1] https://github.com/JuliaDiff/Capstan.jl/ https://github.com/JuliaDiff/Capstan.jl/ [2] https://fluxml.github.io/ https://fluxml.github.io/