Lennart Augustsson

MicroHs is a compiler for Haskell2010. It translates Haskell to SKI style combinators via λ-calculus. The runtime system is quite small with few dependencies.

Functional logic languages have a rich literature, but it is tricky to give them a satisfying semantics. In this paper we describe the Verse calculus, VC, a new core calculus for deterministic functional logic programming. Our main contribution is to equip VC with a small-step rewrite semantics, so that we can reason about a VC program in the same way as one does with lambda calculus; that is, by applying successive rewrites to it. We also show that the rewrite system is confluent for well-behaved terms.

In this paper we investigate how partial evaluation and program transformations can be used on a real problem, namely that of speeding up airline crew scheduling.Scheduling of crews is subject to many rules and restrictions. These restrictions are expressed in a rule language. However, in a given planning situation much is known to be fixed, so the rule set can be partially evaluated with respect to this known input.The approach is somewhat novel in that it uses truly static input data as well as static input data where the values are known only to belong to a set of values.The results of the partial evaluation is quite satisfactory: both compilation and running times have decreased by using it. The partial evaluator is now part of the crew scheduling system that Carmen Systems AB markets and which is in use at most of the major European airlines and in daily production.