SWI-Prolog -- API-function PL

Documentation
- Reference manual
  - Foreign Language Interface
    - The Foreign Include File
      - Calling Prolog from C
        
        Initiating a query from C
        
        PL_open_query()
        
        PL_next_solution()
        
        PL_cut_query()
        
        PL_close_query()
        
        PL_current_query()
        
        PL_query_engine()
        
        PL_call_predicate()
        
        PL_call()
- Packages

Availability:C-language interface function

int PL_call(term_t t, module_t m)

Call term t just like the Prolog predicate once/1. t is called in the module m, or in the context module if m == NULL. Returns TRUE if the call succeeds, FALSE otherwise. If the goal raises an exception the return value is FALSE and the exception term is available using PL_exception(0).^{228Up
to version 9.1.11 the debugger was started and the exception was not
propagated.} Figure 7 shows an example to obtain the number of defined atoms.