library(chr)module contains several predicates that allow inspecting and printing the content of the constraint store.
- Activate the CHR tracer. By default the CHR tracer is activated and deactivated automatically by the Prolog predicates trace/0 and notrace/0.
- Deactivate the CHR tracer. By default the CHR tracer is activated and deactivated automatically by the Prolog predicates trace/0 and notrace/0.
- Define the set of CHR ports on which the CHR tracer asks for user
intervention (i.e. stops). Spec is either a list of ports as
defined in section 9.4.1
or a predefined‘alias'. Defined aliases are:
fullto stop at all ports,
offto never stop, and
defaultto stop at the
applyports. See also leash/1.
- Prints all suspended constraints of module Mod to the
standard output. This predicate is automatically called by the
SWI-Prolog top level at the end of each query for every CHR module
currently loaded. The Prolog flag
chr_toplevel_show_storecontrols whether the top level shows the constraint stores. The value
trueenables it. Any other value disables it.
- Returns a constraint in the constraint store. Via backtracking, all constraints in the store can be enumerated.