Macro swipl_macros::prolog

prolog!() { /* proc-macro */ }

Define prolog predicates to be used from rust code.

The prolog! macro takes a block of function declaration. Each declaration is of the format fn <predicate>(..args..);, where args is a list of argument names. Optionally, a visibility specifier like pub may be used. This much like an ordinary rust function declaration, except that the arguments are typeless.

Each function may be annotated with a #[name("..name..")] attribute, which specifies what the name of this predicate is in prolog. When omitted, the function name will be used.

Each function may be annotated with a #[module("..module..")] attribute, which specifies what prolog module this predicate is in. When omitted, no module is assumed.

For each function declaration, a function will be generated which takes a context argument, followed by all declared arguments, and returns a query opened in that context.

Example:

prolog! {
    fn writeq(term);
    #[name("nl")]
    fn print_a_newline();
    #[module("zlib")]
    pub fn zopen(stream, zstream, options);
}