User Toplevel Manipulation

break

  Recursively start a new Prolog top level. This Prolog top level has it's own stacks, but shares the heap with all break environments and the top level. Debugging is switched off on entering a break and restored on leaving one. The break environment is terminated by typing the system's end-of-file character (control-D). If the -t toplevel command line option is given this goal is started instead of entering the default interactive top level ( prolog/0).

abort

  Abort the Prolog execution and start a new top level. If the -t toplevel command line options is given this goal is started instead of entering the default interactive top level. Break environments are aborted as well. All open files except for the terminal related files are closed. The input- and output stream again refers to user. Erased clauses which could not actually be removed from the database, because they are active in the interpreter, will never be garbage collected after an abort.

halt

  Terminate Prolog execution. Open files are closed and if the command line option -tty is not active the terminal status (see Unix stty(1)) is restored. Hooks may be registered both in Prolog and in foreign code. Prolog hooks are registered using at_halt/1. halt/0 is equivalent to halt(0).

halt( +Status)

  Terminate Prolog execution with given status. Status is an integer. See also halt/0.

prolog

  This goal starts the default interactive top level. prolog/0 is terminated (succeeds) by typing control-D.