"The Revolutionary Optimists" (PBS, Monday). Nicole Newnham and Maren Grainger-Monsen directed this vibrant documentary set in a 9,000-person shantytown in Kolkata, the city formerly written as Calcutta, India. Some critics have dunned the film for lacking a coherent narrative, as if that were something life ever supplied; there is progress for some of its characters and regress for others, and, as in many documentaries it is left to the closing titles to say how the world has gotten on since we left them. There are times, to be sure, that one is not exactly sure how this bit fits with that, but it is also the bits that emotionally matter most: an excited young face, a colorful sari in a dun-colored brickyard, a man and his students dancing in a corridor. The man is Amlan Ganguly, a lawyer turned teacher and activist, and by his own lights an odd duck among his people (his interest in dance and art set him apart), who works for and alongside the young to change their lives, and the future, and everything. His co-stars include two bright and erudite pre-teens, Salim and Sikha, who go hither and yon to alert their neighbors to polio vaccines, break the soccer-gender barrier, bring drinkable water to their neighborhood and put the lie to "tradition," the awful excuse by which the powerful, even among the powerless, strive to keep others weak. An intimate film about big issues, it's both saddening and uplifting; on the one hand the facts of the larger world point to continued bad weather; on the other, rays of human sunshine continue to break out.