American popular music numbers among its composers various strains. There were some composers from the sidewalks of New York, Gershwin, Jerome Kern, Irving Berlin. Some were privileged playboys, like Cole Porter. Mayor Jimmy Walker of New York penned the lyrics for Will You Love Me In December As You Did In May. The stories of these composers and their hits -- some of them dark horses -- are pleasantly told in capsule form. The Man I Love went unnoticed in two plays and caught on here only after Lady Mountbatten popularized it in England. Hosgy Carmichael, Rudolph Friml, Vincent Youmans, Richard Rogers, Oscar Rammeratein, Otto Barbach, Richard Whiting and many others are introduced here in digest form with insights into the hits they wrote. Interest here should not be confined to a juvenile audience. Interwoven with the stories of smash songs is the development of American musical comedy. One can question whether teen-agers, who are listening to a very different kind of music, will really dig it.