  Action description languages, such as A and B, are expressive instruments
introduced for formalizing planning domains and planning problem instances. The
paper starts by proposing a methodology to encode an action language (with
conditional effects and static causal laws), a slight variation of B, using
Constraint Logic Programming over Finite Domains. The approach is then
generalized to raise the use of constraints to the level of the action language
itself. A prototype implementation has been developed, and the preliminary
results are presented and discussed.
  To appear in Theory and Practice of Logic Programming (TPLP)
