Sometimes these two are by different authors , e.g. the musical Fiddler on the Roof has a composer ( Jerry Bock ) , a lyricist ( Sheldon Harnick ) , and the writer of the `` book '' ( Joseph Stein ) . Thus , a musical such as Fiddler on the Roof has a composer ( Jerry Bock ) , a lyricist ( Sheldon Harnick ) , and the writer of the `` book '' ( Joseph Stein ) .