\version "2.19.44"

\language "english"

\header {title = "Such title."}

scoreA = \score {\header {piece = "Piece A"} a'4}

scoreB = \score {\header {piece = "Piece B"} b'4}

scores = #(list scoreA scoreB)

#(define bookGenerator
   (define-void-function
    (
      scoreList
      bookSuffix
      ;; header
      paperBlock
      layoutBlock
      )
    (list? string? scheme? scheme?) ;; add scheme? here
    (let* (
            (book (apply ly:make-book
                    paperBlock
                    #f ;; header
                    (reverse scoreList)))
            )
      (ly:book-process book paperBlock layoutBlock bookSuffix))
    ))

\bookGenerator
\scores
"violinI"
%\header {instrument = "Violin I"}
\paper {}
\layout {}