How to call proof asistant Coq from external software

Question

How to call proof assistant Coq from external software? Does Coq have some API? Is Coq command line interface rich enough to pass arguments in file and receive response in f

Answer 1

The command line seems to be the way to go.

Coq includes several command-line tools, including the coqc compiler. This program takes a Coq theory file as input and tries to compile it. If something is wrong with the theory, the command fails with a non-zero exit code and writes some feedback onto its output streams. If everything is OK, the command is (typically) silent, exits with a zero exit code, and writes a .vo file containing the compiled theory.

For example:

$ cat bad.v
Lemma zero_less_than_one: 0 < 1.
$ coqc bad.v ; echo $?
Error: There are pending proofs
1
$ cat good.v
Lemma zero_less_than_one: 0 < 1.
Proof.
  auto.
Qed.
$ coqc good.v ; echo $?
0

Here are the docs for Coq's command line tools, which can take various flags: https://coq.inria.fr/refman/practical-tools/coq-commands.html

I am aware of two tools that use Coq as a subordinate proof engine: Frama-C and Why3. Looking at the sources at https://github.com/Frama-C/Frama-C-snapshot/blob/master/src/plugins/wp/ProverCoq.ml (methods compile and check) and at https://github.com/AdaCore/why3/tree/master/drivers, these tools also seem to dump Coq theories to a file and then call Coq's command-line tools. As far as I can tell, there is no more direct API for Coq.