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...