In 1959, Sondheim was approached by Laurents and Robbins for a musical version of Gypsy Rose Lee's memoir after Irving Berlin and Cole Porter turned it down. Sondheim agreed, but Ethel Merman – cast as Mama Rose – had just finished "Happy Hunting" with an unknown composer (Harold Karr) and lyricist (Matt Dubey). Although Sondheim wanted to write the music and lyrics, Merman refused to let another first-time composer write for her and demanded that Jule Styne write the music. Sondheim, concerned that writing lyrics again would pigeonhole him as a lyricist, called his mentor for advice. Hammerstein told him he should take the job, because writing a vehicle for a star would be a good learning experience. Sondheim agreed; "Gypsy" opened on May 21, 1959, and ran for 702 performances.