Parameterized Models for On-Line and Off-Line Use

摘要

The Monadic Constraint Programming framework leverages Haskell's rich static type system and powerful abstraction mechanisms to implement an embedded domain specific language (EDSL) for constraint programming. In this paper we show how the same constraint model expressed in the EDSL can be processed in various modes by external constraint solvers. We distinguish between on-line and off-line use of solvers. In off-line mode, the model is not solved; instead it is compiled to lower-level code that will search for solutions when compiled and run. For on-line use, the search can be handled by either the framework or in the external solver. Off-line mode requires recompilation after each change to the model. To avoid repeated recompilation, we separate model from data by means of parameters that need not be known at compile time. Parametrization poses several challenges, which we resolve by embedding the EDSL more deeply.