SWI-Prolog -- trace/0

Documentation
- Reference manual
  - Built-in Predicates
    - Debugging and Tracing Programs
      - trace/0
      - tracing/0
      - notrace/0
      - notrace/1
      - debug/0
      - nodebug/0
      - debugging/0
      - spy/1
      - nospy/1
      - nospyall/0
      - leash/1
      - visible/1
      - unknown/2
      - style_check/1
- Packages

Availability:built-in

Start the tracer. trace/0 itself cannot be seen in the tracer. Note that the Prolog top level treats trace/0 special; it means‘trace the next goal’.