Comparing design by contract to type systems-Collection of common programming errors

It seems most answers assume that contracts are checked dynamically. Note that in some systems contracts are checked statically. In such systems you can think of contracts as a restricted form of dependent types which can be checked automatically. Contrast this with richer dependent types, which are checked interactively, such as in Coq.

See the “Specification Checking” section on Dana Xu’s page for papers on static and hybrid checking (static followed by dynamic) of contracts for Haskell and OCaml. The contract system of Xu includes refinement types and dependent arrows, both of which are dependent types. Early languages with restricted dependent types that are automatically checked include the DML and ATS of Pfenning and Xi. In DML, unlike in Xu’s work, the dependent types are restricted so that automatic checking is complete.

Originally posted 2013-11-09 19:03:25.