Constraints to stop higher-order deforestation

Wadler's deforestation algorithm removes intermediate data structures from functional programs. To be appropriate for inclusion in a compiler, deforestation must terminate on all programs. Several techniques exist to ensure termination of deforestation on all first-order programs, but a technique for higher-order programs was only recently introduced by Hamilton and later Marlow. We present a new technique for ensuring termination of deforestation on all higher-order programs that allows useful transformation steps prohibited in Hamilton's and Marlow's techniques. The technique uses a constraint-based higher-order control-flow analysis.