A Proof Dedicated Meta-Language

We describe a proof dedicated meta-language, called Ltac, in the context of the Coq proof assistant. This new layer of meta-language is quite appropriate to write small and local automations. Ltac is essentially a small functional core with recursors and powerful pattern-matching operators for Coq terms but also for proof contexts. As Ltac is not complete, we describe an interface between Ltac and the full programmable meta-language of the system (Objective Caml), which is also the implementation language. This interface is based on a quotation system where we can use Ltac’s syntax in ML files, and where it is possible to insert ML code in Ltac scripts by means of antiquotations. In that way, the two meta-languages are not opposed and we give an example where they fairly cooperate. Thus, this shows that a LCF-like system with a two-level meta-language is completely realistic.