Han-Wen Nienhuys <hanw...@gmail.com> writes: > On Mon, Jan 27, 2020 at 11:33 AM David Kastrup <d...@gnu.org> wrote: >> > >> > When calling the macro twice, we'll define add-session-variable twice, >> > which seems fishy. >> >> I think you got confused here. A macro is just an ordinary function on >> its inside, it only differs in its calling conventions during >> evaluation: instead of evaluating its arguments and calling the function >> body like with ordinary functions, it is called with unevaluated >> arguments and the result is then evaluated in its expression. >> >> add-session-variable is a local function defined inside of >> define-session. The effect is that it is not callable externally, and >> not modifiable externally. It is just putting stuff near to where it is >> being used (it is used as a function in the expansion of the macro). >> >> define-session is a macro since its use parallels the use of define , >> and the first argument of define is the symbol to be defined which must >> not be evaluated before define-session is being called. > > Thanks, I got it now. I sent a mail to the guile-devel list to > inquire what is going on.
Got any comments about macros being sooo yesterday compared to syntax forms? Syntax forms actually don't work in LilyPond: there was an incompatibility because the 1.8 implementation will balk if some symbol used in syntax forms already has a definition, and we have that. I forgot the exact symbol at fault. I think it was some music function name. -- David Kastrup
