prolog interpreter on linux?

I've decided to learn prolog. What's a good interpreter to use? Even better if it has a decent c/c++ ffi.

How do I know if Prolog is installed?

Then check your installation, call SWI-Prolog from a terminal shell as follows: - In the shell, type in …> ./swipl which should open the interpreter, i.e., you should see something like … ?- If you get an error that the command swipl is not known, check that your PATH variable includes a path to SWI-Prolog.

I'd recommend GNU Prolog, because that seems to be the standard, but I've also heard good things about SWI-Prolog.