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check.pl -- Consistency checking
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This library provides some consistency checks for the loaded Prolog program. The predicate make/0 runs list_undefined/0 to find undefined predicates in `user' modules.

See also
- gxref/0 provides a graphical cross referencer
- PceEmacs performs real time consistency checks while you edit
- library(prolog_xref) implements `offline' cross-referencing
- library(prolog_codewalk) implements `online' analysis
Source check is det
Run all consistency checks defined by checker/2. Checks enabled by default are:

The checker can be expanded or restricted by modifying the dynamic multifile hook checker/2.

The checker may be used in batch, e.g., for CI workflows by calling SWI-Prolog as below. Note that by using -l to load the program, the program is not started if it used initialization/2 of type main to start the program.

swipl -q --on-warning=status --on-error=status \
      -g check -t halt -l myprogram.pl
Source list_undefined is det
Source list_undefined(+Options) is det
Report undefined predicates. This predicate finds undefined predicates by decompiling and analyzing the body of all clauses. Options:
module_class(+Classes)
Process modules of the given Classes. The default for classes is [user]. For example, to include the libraries into the examination, use [user,library].
See also
- gxref/0 provides a graphical cross-referencer.
- make/0 calls list_undefined/0
Source list_autoload is det
Report predicates that may be auto-loaded. These are predicates that are not defined, but will be loaded on demand if referenced.
See also
- autoload/0
To be done
- This predicate uses an older mechanism for finding undefined predicates. Should be synchronized with list undefined.
Source list_redefined
Lists predicates that are defined in the global module user as well as in a normal module; that is, predicates for which the local definition overrules the global default definition.
Source list_cross_module_calls is det
List calls from one module to another using Module:Goal where the callee is not defined exported, public or multifile, i.e., where the callee should be considered private.
Source list_void_declarations is det
List predicates that have declared attributes, but no clauses.
Source list_trivial_fails is det
Source list_trivial_fails(+Options) is det
List goals that trivially fail because there is no matching clause. Options:
module_class(+Classes)
Process modules of the given Classes. The default for classes is [user]. For example, to include the libraries into the examination, use [user,library].
Source trivial_fail_goal(:Goal)[multifile]
Multifile hook that tells list_trivial_fails/0 to accept Goal as valid.
Source list_strings is det
Source list_strings(+Options) is det
List strings that appear in clauses. This predicate is used to find portability issues for changing the Prolog flag double_quotes from codes to string, creating packed string objects. Warnings may be suppressed using the following multifile hooks:
See also
- Prolog flag double_quotes.
Source list_rationals is det
Source list_rationals(+Options) is det
List rational numbers that appear in clauses. This predicate is used to find portability issues for changing the Prolog flag rational_syntax to natural, creating rational numbers from <integer>/<nonneg>. Options:
module_class(+Classes)
Determines the modules classes processed. By default only user code is processed. See prolog_program_clause/2.
arithmetic(+Bool)
If true (default false) also warn on rationals appearing in arithmetic expressions.
See also
- Prolog flag rational_syntax and prefer_rationals.
Source list_format_errors is det
Source list_format_errors(+Options) is det
List argument errors for format/2,3.
Source string_predicate(:PredicateIndicator)[multifile]
Multifile hook to disable list_strings/0 on the given predicate. This is typically used for facts that store strings.
Source valid_string_goal(+Goal) is semidet[multifile]
Multifile hook that qualifies Goal as valid for list_strings/0. For example, format("Hello world~n") is considered proper use of string constants.
Source checker(:Goal, +Message:text) is nondet[multifile]
Register code validation routines. Each clause defines a Goal which performs a consistency check executed by check/0. Message is a short description of the check. For example, assuming the my_checks module defines a predicate list_format_mistakes/0:
:- multifile check:checker/2.
check:checker(my_checks:list_format_mistakes,
              "errors with format/2 arguments").

The predicate is dynamic, so you can disable checks with retract/1. For example, to stop reporting redefined predicates:

retract(check:checker(list_redefined,_)).

Re-exported predicates

The following predicates are exported from this file while their implementation is defined in imported modules or non-module files loaded by this module.

Source list_undefined is det
Source list_undefined(+Options) is det
Report undefined predicates. This predicate finds undefined predicates by decompiling and analyzing the body of all clauses. Options:
module_class(+Classes)
Process modules of the given Classes. The default for classes is [user]. For example, to include the libraries into the examination, use [user,library].
See also
- gxref/0 provides a graphical cross-referencer.
- make/0 calls list_undefined/0
Source list_trivial_fails is det
Source list_trivial_fails(+Options) is det
List goals that trivially fail because there is no matching clause. Options:
module_class(+Classes)
Process modules of the given Classes. The default for classes is [user]. For example, to include the libraries into the examination, use [user,library].
Source list_strings is det
Source list_strings(+Options) is det
List strings that appear in clauses. This predicate is used to find portability issues for changing the Prolog flag double_quotes from codes to string, creating packed string objects. Warnings may be suppressed using the following multifile hooks:
See also
- Prolog flag double_quotes.
Source list_rationals is det
Source list_rationals(+Options) is det
List rational numbers that appear in clauses. This predicate is used to find portability issues for changing the Prolog flag rational_syntax to natural, creating rational numbers from <integer>/<nonneg>. Options:
module_class(+Classes)
Determines the modules classes processed. By default only user code is processed. See prolog_program_clause/2.
arithmetic(+Bool)
If true (default false) also warn on rationals appearing in arithmetic expressions.
See also
- Prolog flag rational_syntax and prefer_rationals.
Source list_format_errors is det
Source list_format_errors(+Options) is det
List argument errors for format/2,3.

Undocumented predicates

The following predicates are exported, but not or incorrectly documented.

Source list_cross_module_calls(Arg1)