Optimizing lazy functional programs using flow inference

Abstract

Nonstrict higher order functional programming languages are notorious for their low run time efficiency. Optimizations based on flow analysis, which determines for each variable x in a program which expressions could have originated the value of x, can improve the situation by removing redundant eval and thunk operations, avoiding thunk updates, and allowing the use of unboxed representations of some data. We formulate flow analysis as an inference problem in a type system built using type inclusion constraints and an algorithm for solving these constraints is also given.