St. Luke's Catholic Church will be the setting tonight at 7:30 for the wedding of Sally Swails and William Zafian, Baton Rouge, La. She is the daughter of Mr. and Mrs. Floyd Swails. He is the son of Mrs. William Zafian and the late Mr. Zafian. The future bride attended Ball State University. The future bridegroom graduated from Purdue University and attends Louisiana State University, Baton Rouge, where he is working on a master's degree. He is a member of Phi Kappa Phi and Omega Chi Epsilon hon