object

`toychrdb`

Simple CHR interpreter/debugger based on the refined operational semantics of CHRs.

Availability:

logtalk_load(toychr(loader))

Author: Gregory J. Duck; adapted to Logtalk by Paulo Moura.
Version: 0:8:0
Date: 2026-08-10

License: GPL-2.0-or-later

Compilation flags:

static, context_switching_calls

Implements:

public expanding

Uses:

list

user

Remarks:

(none)

Inherited public predicates:

goal_expansion/2 term_expansion/2

Public predicates 

`chr_is/2`

Runs a goal against the entity CHR program and returns the resulting constraint store as a conjunction.

Compilation flags:

static

Template:

chr_is(Result,Goal)

Mode and number of proofs:

chr_is(?nonvar,+callable) - zero_or_one

`chr_trace/0`

Enables the CHR interactive trace debugger. Similar to the trace/0 standard predicate.

Compilation flags:

static

Mode and number of proofs:

chr_trace - one

`chr_notrace/0`

Disables the CHR interactive trace debugger. Similar to the notrace/0 standard predicate.

Compilation flags:

static

Mode and number of proofs:

chr_notrace - one

`chr_spy/1`

Sets a spy point on the activation of constraints matching the given pattern.

Compilation flags:

static

Template:

chr_spy(Pattern)

Mode and number of proofs:

chr_spy(@callable) - one

`chr_nospy/0`

Disables all spy points.

Compilation flags:

static

Mode and number of proofs:

chr_nospy - one

`chr_no_spy/1`

Not yet implemented; disables the spy point on constraints matching the given pattern.

Compilation flags:

static

Template:

chr_no_spy(Pattern)

Mode and number of proofs:

chr_no_spy(@callable) - zero

`chr_option/2`

Sets a debugger or compiler option. See the file documentation for the supported options and their values.

Compilation flags:

static

Template:

chr_option(Option,Value)

Mode and number of proofs:

chr_option(+atom,+atom) - zero_or_one

Protected predicates 

`current_prog/1`

Compiled CHR program generated from the entity chr_constraint, handler, and rules terms.

Compilation flags:

static

Template:

current_prog(Program)

Mode and number of proofs:

current_prog(?callable) - zero_or_one

`chr_option_print_trace/0`

True when trace printing is enabled.

Compilation flags:

dynamic

Mode and number of proofs:

chr_option_print_trace - zero_or_one

`chr_option_trace_interactive/0`

True when interactive tracing is enabled.

Compilation flags:

dynamic

Mode and number of proofs:

chr_option_trace_interactive - zero_or_one

`chr_option_optimization_level/1`

Current compiler optimization level.

Compilation flags:

dynamic

Template:

chr_option_optimization_level(Level)

Mode and number of proofs:

chr_option_optimization_level(?integer) - zero_or_one

`chr_option_show_stack/0`

True when the execution stack is shown while tracing.

Compilation flags:

dynamic

Mode and number of proofs:

chr_option_show_stack - zero_or_one

`chr_option_show_store/0`

True when the constraint store is shown while tracing.

Compilation flags:

dynamic

Mode and number of proofs:

chr_option_show_store - zero_or_one

`chr_option_show_history/0`

True when the propagation history is shown while tracing.

Compilation flags:

dynamic

Mode and number of proofs:

chr_option_show_history - zero_or_one

`chr_option_show_id/0`

True when the current constraint identifier is shown while tracing.

Compilation flags:

dynamic

Mode and number of proofs:

chr_option_show_id - zero_or_one

`chr_option_allow_deep_guards/0`

True when CHR constraints are allowed in rule guards or if-conditions.

Compilation flags:

dynamic

Mode and number of proofs:

chr_option_allow_deep_guards - zero_or_one

`chr_next_state/1`

Stack length recorded to detect when the next debugger step is reached.

Compilation flags:

dynamic

Template:

chr_next_state(Length)

Mode and number of proofs:

chr_next_state(?integer) - zero_or_one

`chr_spy_point/1`

Asserted clause matching constraints on which a spy point is set.

Compilation flags:

dynamic

Template:

chr_spy_point(Constraint)

Mode and number of proofs:

chr_spy_point(@callable) - zero_or_more

Private predicates 

`chr_rule_/1`

Asserted CHR rule term collected during term-expansion, consumed when compiling the entity program.

Compilation flags:

dynamic

Template:

chr_rule_(Rule)

Mode and number of proofs:

chr_rule_(?callable) - zero_or_more

Operators 

(none)

toychrdb

`toychrdb`