Lilypond: "Wrong type to apply: #<Score>"

Question

I don't know what's going wrong with this snippet:

\version "2.24"

multiDynScoresDoc = #(define-void-function
  (filename title staves)
  (string? string? list?)
  (toplevel-book-handler #{
    \book {
      \bookOutputName #filename

      \header {
        title = #title
      }

      $@(map
        (lambda (staff) (#{
          \score {
            $staff
          }
        #}))
        staves
      )
    }
  #})
)

staffA = \new Staff { \time 2/4 a8 a8 a8 a8 }
staffB = \new Staff { \time 2/4 b8 b8 b8 b8 }
staffC = \new Staff { \time 2/4 c8 c8 c8 c8 }

\multiDynScoresDoc #"test" "Test" #(list 
  staffA staffB staffC
)

Lilypond output:

GNU LilyPond 2.24.3 (running Guile 2.2)
Processing `./test.ly'
Parsing...
./test.ly:14:8: error: Guile signaled an error for the expression beginning here
      $
       @(map
Wrong type to apply: #<Score>
./test.ly:30:1: error: error in #{ ... #}

\multiDynScoresDoc #"test" "Test" #(list 
fatal error: failed files: "./test.ly"

Answer 1

This is just a Scheme error since you are trying to call a score as a function in Scheme.

Instead of (lambda (staff) (#{… you need to write (lambda (staff) #{… and of course also remove the corresponding closing parenthesis.

If you don't, the lambda form does not return a score but rather tries calling the score and return the result from that call.