On 28/01/2023 16:51, David Kastrup wrote: > Jean Abou Samra <j...@abou-samra.fr> writes: > >>> Le 28 janv. 2023 à 08:01, Darren Ng <un1...@gmail.com> a écrit : >>> >>> [subject] How to define a macro that expands to a percussion "pitch"? >> >> >> It may be worth noting that LilyPond does not have macros, only >> variables and regular functions. Call me pedantic, but I think it is >> helpful not to conflate the two. > > It's a hybrid, actually. In Lispy terms, the difference between a > function and a macro is that a function evaluates its arguments while a > macro evaluates the result of executing the macro body on the > unevaluated arguments. > > LilyPond evaluates a music/event/scheme/void function's body after > reading its arguments but the reading/interpretation of the arguments is > directed by the predicates. > > So a music/event/scheme/void function does evaluate some of its parts > (the predicates) in order to direct the syntactic interpretation of its > arguments.
OK, I grant you that. Still very different from the concepts of "macros" found in Scheme, Lisp, C, TeX or Rust, though. >> There is no way in LilyPond to make a variable "just be replaced by >> this code". Sometimes users get confused by this (I remember a >> question about defining a chord modifier, which was similar to this >> one). Instead, there are functions, as well as some other mechanisms >> like drumPitchNames. > > In general, things are not purely functional but the categories and > interpretation change around more by ad-hoc conditions than a cohesive > macro mechanism. Yup.
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