Also Bucklescript and ReasonML respectively provide OCaml and javascript-like syntax over the same AST and can translate your code between the two (as seen in the try reasonML UI).
That's not exactly how it works: Bucklescript is a JS backend for OCaml, and ReasonML is an alternative syntax for OCaml. Bucklescript is not involved in this translation, it generates the JS output on the top right pane of that UI.
Wolfram Mathematica (or "the Wolfram language") introduced "forms" for that, for instance https://reference.wolfram.com/language/ref/FullForm.html or https://reference.wolfram.com/language/ref/InputForm.html or, quite charming in the math context, https://reference.wolfram.com/language/ref/TraditionalForm.h... or https://reference.wolfram.com/language/ref/TeXForm.html -- See also https://reference.wolfram.com/language/tutorial/EverythingIs...