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The chr
module exports several predicates that allow
inspecting and printing the content of the constraint store.
chr_trace/0
Activate the CHR tracer. By default the CHR tracer is activated and
deactivated automatically by the Prolog predicates trace/0
and
notrace/0
.
chr_notrace/0
De-activate the CHR tracer. By default the CHR tracer is activated and
deactivated automatically by the Prolog predicates trace/0
and
notrace/0
.
chr_leash(+Spec)
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 CHR Ports or a predefined alias. Defined aliases
are: full
to stop at all ports, none
or off
to
never stop, and default
to stop at the call
,
exit
, fail
, wake
and apply
ports.
See also leash/1
.
chr_flag(+FlagName, ?OldValue, ?NewValue)
OldValue is the value of the CHR flag FlagName, and the new value of FlagName is set to NewValue. The valid CHR flag are the following:
toplevel_show_store
If on
(the default), then the Prolog top level displays the constraint store at the
end of each query. If off
, then the top level does not display this.
generate_debug_info
Provides the default if the debug
option is not given.
The valid values are true
and false
(the default).
optimize
Provides the default if the optimize
option is not given.
The valid values are full
and off
(the default).
chr_show_store(+Mod)
Prints all suspended constraints of module Mod to the current output stream.
find_chr_constraint(-Constraint) since release 4.3.2
Unifies Constraint with a constraint in the store.