define-void-function

[Freeman Gilmore]

Need lots of help this.   Starting with this:

sum = #(lambda x
   (define A (apply + x))
   (display A))

#(sum 2 3 4 5)     %  14 (from LilyPond Log)

I am guessing from reading “Extending LilyPond“ the above could be maid into:

function =
   (define-void-function
   (arg1 arg2 …)
   (type1? type2? …)
   body)

This is one of my many tries: but nothing works:

sum = #(define-void-function  (x)
   (lambda x
   (define A (apply + x))
   (display A)))

{\sum 2 3 4}

Thank you, ƒg