Strictness analysis — a practical approach

Significant improvements in performance arise if we can arrange for parallel execution of programs. The absence of side effects in functional languages allows concurrent evaluation of the program, but in lazy implementations this risks wasting work by evaluating expressions which are subsequently discarded. We discuss the use of strictness analysis to determine at compile time which parts of program evaluation can safely be carried out concurrently. We give a practical explanation of this technique, concentrating particularly on the problem of finding fixed points.