Salient features of an executable specification language and its environment

The executable specification language PAISLey and its environment are presented as a case study in the design of computer languages. It is shown that PAISLey is unusual (and for some features unique) in having the following desirable features: (1) there is both synchronous and asynchronous parallelism free of mutual-exclusion problems, (2) all computations are encapsulated, (3) specifications in the language can be executed no matter how incomplete they are, (4) timing constraints are executable, (5) specifications are organized so that bounded resource consumption can be guaranteed, (6) almost all forms of inconsistency can be detected by automated checking, and (7) a notable degree of simplicity is maintained. Conclusions are drawn concerning the differences between executable specification languages and programming languages, and potential uses for PAISLey are given.