(defmacro-public define-syntax-function (type args signature . body)
"Helper macro for `ly:make-music-function'.
Syntax:
- (define-syntax-function (result-type? parser location arg1 arg2 ...) (result-type? arg1-type arg2-type ...)
+ (define-syntax-function result-type? (parser location arg1 arg2 ...) (arg1-type arg2-type ...)
...function body...)
argX-type can take one of the forms @code{predicate?} for mandatory