SWI-Prolog 7.4.2 Reference Manual: Section 6.6

## 6.6 Interacting with modules from the top level

Debugging often requires interaction with predicates that reside in modules: running them, setting spy points on them, etc. This can be achieved using the <module>:<term> construct explicitly as described above. In SWI-Prolog, you may also wish to omit the module qualification. Setting a spy point ( spy/1) on a plain predicate sets a spy point on any predicate with that name in any module. Editing ( edit/1) or calling an unqualified predicate invokes the DWIM (Do What I Mean) mechanism, which generally suggests the correct qualified query.

Mainly for compatibility, we provide module/1 to switch the module with which the interactive top level interacts:

module(+Module)
  The call `module(Module)` may be used to switch the default working module for the interactive top level (see prolog/0). This may be used when debugging a module. The example below lists the clauses of file_of_label/2 in the module `tex`.

      1 ?- module(tex).
      true.
      tex: 2 ?- listing(file_of_label/2).
      ...