I'm trying, in a somewhat haphazard way, to learn some more Scheme, but I'm clearly not reading the right stuff to solve the following problem. Please can someone point me in the right direction.
I have the following function (hugely abbreviated here):
foo = #(define-music-function( P L arg1 arg2 arg3 ... ) (type1? type2? type3? ... ) #{ \mark \markup { % bunch of stuff } #} )
I would like to pass an argument, arg4 say, equal to "system" or "staff". \mark would be replaced by a parameter taking the values: \mark if arg4 == "system", and <>^ if arg4 == "staff"