Well, it's not like a type systems of today :)

Well, the full generality of spec allows arbitrary code in predicates, so it is in general computationally undecidable to statically check that a program meets such a general spec.

spec has been designed with run-time checking (and generation, etc.) in mind, not trying to limit itself to what can be statically checked, although subsets of it can be: https://github.com/arohner/spectrum

Because folks keep asking about our "coercing specs" at work, we just open-sourced them https://github.com/worldsingles/web-specs worldsingles/web-specs {:mvn/version "0.1.0"}