Section: New Results

Reflection without Remorse

A series of list appends or monadic binds for many monads performs algorithmically worse when it is left-associated. Continuation-passing style (CPS) is well-known to cure this severe dependence of performance on the association pattern. The advantage of CPS dwindles or disappears if we have to examine or modify the intermediate result of a series of appends or binds, before continuing the series. Such examination is frequently needed, for example, to control search in non-determinism monads. Atze van der Ploeg (together with Oleg Kiselyov) developed an alternative approach that is just as general as CPS but more robust: it makes series of binds and other such operations efficient regardless of the association pattern [30] . This solution solves previously undocumented, severe performance problems in iteratees, LogicT transformers, free monads and extensible effects.