SWI-Prolog 7.7.1 Reference Manual: Section F.2

## F.2 Library predicates

### F.2.1 library(aggregate)

aggregate/3 | Aggregate bindings in Goal according to Template.
aggregate/4 | Aggregate bindings in Goal according to Template.
aggregate_all/3 | Aggregate bindings in Goal according to Template.
aggregate_all/4 | Aggregate bindings in Goal according to Template.
foreach/2 | True if conjunction of results is true.
free_variables/4 | Find free variables in bagof/setof template.

### F.2.2 library(apply)

convlist/3 | Similar to maplist/3, but elements for which call(Goal, ElemIn, _) fails are omitted from ListOut.
exclude/3 | Filter elements for which Goal fails.
foldl/4 | Fold a list, using arguments of the list as left argument.
foldl/5 | Fold a list, using arguments of the list as left argument.
foldl/6 | Fold a list, using arguments of the list as left argument.
foldl/7 | Fold a list, using arguments of the list as left argument.
include/3 | Filter elements for which Goal succeeds.
maplist/2 | True if Goal can successfully be applied on all elements of List.
maplist/3 | As maplist/2, operating on pairs of elements from two lists.
maplist/4 | As maplist/2, operating on triples of elements from three lists.
maplist/5 | As maplist/2, operating on quadruples of elements from four lists.
partition/4 | Filter elements of List according to Pred.
partition/5 | Filter List according to Pred in three sets.
scanl/4 | Left scan of list.
scanl/5 | Left scan of list.
scanl/6 | Left scan of list.
scanl/7 | Left scan of list.

### F.2.3 library(assoc)

assoc_to_list/2 | Translate assoc into a pairs list
assoc_to_keys/2 | Translate assoc into a key list
assoc_to_values/2 | Translate assoc into a value list
empty_assoc/1 | Test/create an empty assoc
gen_assoc/3 | Non-deterministic enumeration of assoc
get_assoc/3 | Get associated value
get_assoc/5 | Get and replace associated value
list_to_assoc/2 | Translate pair list to assoc
map_assoc/2 | Test assoc values
map_assoc/3 | Map assoc values
max_assoc/3 | Max key-value of an assoc
min_assoc/3 | Min key-value of an assoc
ord_list_to_assoc/2 | Translate ordered list into an assoc
put_assoc/4 | Add association to an assoc

### F.2.4 library(broadcast)

broadcast/1 | Send event notification
broadcast_request/1 | Request all agents
listen/2 | Listen to event notifications
listen/3 | Listen to event notifications
unlisten/1 | Stop listening to event notifications
unlisten/2 | Stop listening to event notifications
unlisten/3 | Stop listening to event notifications
listening/3 | Who is listening to event notifications?

### F.2.5 library(charsio)

atom_to_chars/2 | Convert Atom into a list of character codes.
atom_to_chars/3 | Convert Atom into a difference list of character codes.
format_to_chars/3 | Use format/2 to write to a list of character codes.
format_to_chars/4 | Use format/2 to write to a difference list of character codes.
number_to_chars/2 | Convert Atom into a list of character codes.
number_to_chars/3 | Convert Number into a difference list of character codes.
open_chars_stream/2 | Open Codes as an input stream.
read_from_chars/2 | Read Codes into Term.
read_term_from_chars/3 | Read Codes into Term.
with_output_to_chars/2 | Run Goal as with once/1.
with_output_to_chars/3 | Run Goal as with once/1.
with_output_to_chars/4 | Same as with_output_to_chars/3 using an explicit stream.
write_to_chars/2 | Write a term to a code list.
write_to_chars/3 | Write a term to a code list.

### F.2.6 library(check)

check/0 | Run all consistency checks defined by checker/2.
checker/2 | Register code validation routines.
list_autoload/0 | Report predicates that may be auto-loaded.
list_redefined/0 | 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.
list_strings/0 | List strings that appear in clauses.
list_strings/1 | List strings that appear in clauses.
list_trivial_fails/0 | List goals that trivially fail because there is no matching clause.
list_trivial_fails/1 | List goals that trivially fail because there is no matching clause.
list_undefined/0 | Report undefined predicates.
list_undefined/1 | Report undefined predicates.
list_void_declarations/0 | List predicates that have declared attributes, but no clauses.
string_predicate/1 | Multifile hook to disable list_strings/0 on the given predicate.
trivial_fail_goal/1 | Multifile hook that tells list_trivial_fails/0 to accept Goal as valid.
valid_string_goal/1 | Multifile hook that qualifies Goal as valid for list_strings/0.

### F.2.7 library(clpb)

labeling/1 | Enumerate concrete solutions.
random_labeling/2 | Select a single random solution.
sat/1 | True iff Expr is a satisfiable Boolean expression.
sat_count/2 | Count the number of admissible assignments.
taut/2 | Tautology check.
weighted_maximum/3 | Enumerate weighted optima over admissible assignments.

### F.2.8 library(clpfd)

#/\/2 | P and Q hold.
#</2 | The arithmetic expression X is less than Y.
#<==/2 | Q implies P.
#<==>/2 | P and Q are equivalent.
#=/2 | The arithmetic expression X equals Y.
#=</2 | The arithmetic expression X is less than or equal to Y.
#==>/2 | P implies Q.
#>/2 | Same as Y `#<` X.
#>=/2 | Same as Y `#=<` X.
#\/1 | Q does _not_ hold.
#\/2 | Either P holds or Q holds, but not both.
#\//2 | P or Q holds.
#\=/2 | The arithmetic expressions X and Y evaluate to distinct integers.
all_different/1 | Like all_distinct/1, but with weaker propagation.
all_distinct/1 | True iff Vars are pairwise distinct.
automaton/3 | Describes a list of finite domain variables with a finite automaton.
automaton/8 | Describes a list of finite domain variables with a finite automaton.
chain/2 | Zs form a chain with respect to Relation.
circuit/1 | True iff the list Vs of finite domain variables induces a Hamiltonian circuit.
cumulative/1 | Equivalent to cumulative(Tasks, [limit(1)]).
cumulative/2 | Schedule with a limited resource.
disjoint2/1 | True iff Rectangles are not overlapping.
element/3 | The N-th element of the list of finite domain variables Vs is V.
fd_dom/2 | Dom is the current domain (see in/2) of Var.
fd_inf/2 | Inf is the infimum of the current domain of Var.
fd_size/2 | Reflect the current size of a domain.
fd_sup/2 | Sup is the supremum of the current domain of Var.
fd_var/1 | True iff Var is a CLP(FD) variable.
global_cardinality/2 | Global Cardinality constraint.
global_cardinality/3 | Global Cardinality constraint.
in/2 | Var is an element of Domain.
indomain/1 | Bind Var to all feasible values of its domain on backtracking.
ins/2 | The variables in the list Vars are elements of Domain.
label/1 | Equivalent to labeling([], Vars).
labeling/2 | Assign a value to each variable in Vars.
lex_chain/1 | Lists are lexicographically non-decreasing.
scalar_product/4 | True iff the scalar product of Cs and Vs is in relation Rel to Expr.
serialized/2 | Describes a set of non-overlapping tasks.
sum/3 | The sum of elements of the list Vars is in relation Rel to Expr.
transpose/2 | Transpose a list of lists of the same length.
tuples_in/2 | True iff all Tuples are elements of Relation.
zcompare/3 | Analogous to compare/3, with finite domain variables A and B.

### F.2.9 library(clpqr)

entailed/1 | Check if constraint is entailed
inf/2 | Find the infimum of an expression
sup/2 | Find the supremum of an expression
minimize/1 | Minimizes an expression
maximize/1 | Maximizes an expression
bb_inf/3 | Infimum of expression for mixed-integer problems
bb_inf/4 | Infimum of expression for mixed-integer problems
bb_inf/5 | Infimum of expression for mixed-integer problems
dump/3 | Dump constraints on variables

### F.2.10 library(csv)

csv_options/2 | Compiled is the compiled representation of the CSV processing options as they may be passed into csv`//`2, etc.
csv_read_file/2 | Read a CSV file into a list of rows.
csv_read_file/3 | Read a CSV file into a list of rows.
csv_read_file_row/3 | True when Row is a row in File.
csv_read_row/3 | Read the next CSV record from Stream and unify the result with Row.
csv_write_file/2 | Write a list of Prolog terms to a CSV file.
csv_write_file/3 | Write a list of Prolog terms to a CSV file.
csv_write_stream/3 | Write the rows in Data to Stream.
csv//1 | Prolog DCG to `read/write' CSV data.
csv//2 | Prolog DCG to `read/write' CSV data.

### F.2.11 library(debug)

assertion/1 | Acts similar to C assert() macro.
assertion_failed/2 | This hook is called if the Goal of assertion/1 fails.
debug/1 | Add/remove a topic from being printed.
debug/3 | Format a message if debug topic is enabled.
debug_message_context/1 | Specify additional context for debug messages.
debug_print_hook/3 | Hook called by debug/3.
debugging/1 | Examine debug topics.
debugging/2 | Examine debug topics.
list_debug_topics/0 | List currently known debug topics and their setting.
nodebug/1 | Add/remove a topic from being printed.

### F.2.12 library(error)

current_type/3 | True when Type is a currently defined type and Var satisfies Type of the body term Body succeeds.
domain_error/2 | The argument is of the proper type, but has a value that is outside the supported values.
existence_error/2 | Term is of the correct type and correct domain, but there is no existing (external) resource that is represented by it.
has_type/2 | True if Term satisfies Type.
instantiation_error/1 | An argument is under-instantiated.
is_of_type/2 | True if Term satisfies Type.
must_be/2 | True if Term satisfies the type constraints for Type.
permission_error/3 | It is not allowed to perform Action on the object Term that is of the given Type.
representation_error/1 | A representation error indicates a limitation of the implementation.
resource_error/1 | A goal cannot be completed due to lack of resources.
syntax_error/1 | A text has invalid syntax.
type_error/2 | Tell the user that Term is not of the expected Type.
uninstantiation_error/1 | An argument is over-instantiated.

### F.2.13 library(iostream)

### F.2.14 library(summaries.d/iostream/tex)

### F.2.15 library(lists)

append/2 | Concatenate a list of lists.
append/3 | List1AndList2 is the concatenation of List1 and List2.
delete/3 | Delete matching elements from a list.
flatten/2 | Is true if FlatList is a non-nested version of NestedList.
intersection/3 | True if Set3 unifies with the intersection of Set1 and Set2.
is_set/1 | True if Set is a proper list without duplicates.
last/2 | Succeeds when Last is the last element of List.
list_to_set/2 | True when Set has the same elements as List in the same order.
max_list/2 | True if Max is the largest number in List.
max_member/2 | True when Max is the largest member in the standard order of terms.
member/2 | True if Elem is a member of List.
min_list/2 | True if Min is the smallest number in List.
min_member/2 | True when Min is the smallest member in the standard order of terms.
nextto/3 | True if Y directly follows X in List.
nth0/3 | True when Elem is the Index'th element of List.
nth0/4 | Select/insert element at index.
nth1/3 | Is true when Elem is the Index'th element of List.
nth1/4 | As nth0/4, but counting starts at 1.
numlist/3 | List is a list [Low, Low+1, ... High].
permutation/2 | True when Xs is a permutation of Ys.
prefix/2 | True iff Part is a leading substring of Whole.
proper_length/2 | True when Length is the number of elements in the proper list List.
reverse/2 | Is true when the elements of List2 are in reverse order compared to List1.
same_length/2 | Is true when List1 and List2 are lists with the same number of elements.
select/3 | Is true when List1, with Elem removed, results in List2.
select/4 | Select from two lists at the same positon.
selectchk/3 | Semi-deterministic removal of first element in List that unifies with Elem.
selectchk/4 | Semi-deterministic version of select/4.
subset/2 | True if all elements of SubSet belong to Set as well.
subtract/3 | Delete all elements in Delete from Set.
sum_list/2 | Sum is the result of adding all numbers in List.
union/3 | True if Set3 unifies with the union of Set1 and Set2.

### F.2.16 library(main)

argv_options/3 | Generic transformation of long commandline arguments to options.
main/0 | Call main/1 using the passed command-line arguments.

### F.2.17 library(option)

dict_options/2 | Convert between an option list and a dictionary.
merge_options/3 | Merge two option lists.
meta_options/3 | Perform meta-expansion on options that are module-sensitive.
option/2 | Get an Option from OptionList.
option/3 | Get an Option from OptionList.
select_option/3 | Get and remove Option from an option list.
select_option/4 | Get and remove Option with default value.

### F.2.18 library(optparse)

opt_arguments/3 | Extract commandline options according to a specification.
opt_help/2 | True when Help is a help string synthesized from OptsSpec.
opt_parse/4 | Equivalent to opt_parse(OptsSpec, ApplArgs, Opts, PositionalArgs, `[]`).
opt_parse/5 | Parse the arguments Args (as list of atoms) according to OptsSpec.
parse_type/3 | Hook to parse option text Codes to an object of type Type.

### F.2.19 library(ordsets)

is_ordset/1 | True if Term is an ordered set.
list_to_ord_set/2 | Transform a list into an ordered set.
ord_add_element/3 | Insert an element into the set.
ord_del_element/3 | Delete an element from an ordered set.
ord_disjoint/2 | True if Set1 and Set2 have no common elements.
ord_empty/1 | True when List is the empty ordered set.
ord_intersect/2 | True if both ordered sets have a non-empty intersection.
ord_intersect/3 | Intersection holds the common elements of Set1 and Set2.
ord_intersection/2 | Intersection of a powerset.
ord_intersection/3 | Intersection holds the common elements of Set1 and Set2.
ord_intersection/4 | Intersection and difference between two ordered sets.
ord_memberchk/2 | True if Element is a member of OrdSet, compared using ==.
ord_selectchk/3 | Selectchk/3, specialised for ordered sets.
ord_seteq/2 | True if Set1 and Set2 have the same elements.
ord_subset/2 | Is true if all elements of Sub are in Super.
ord_subtract/3 | Diff is the set holding all elements of InOSet that are not in NotInOSet.
ord_symdiff/3 | Is true when Difference is the symmetric difference of Set1 and Set2.
ord_union/2 | True if Union is the union of all elements in the superset SetOfSets.
ord_union/3 | Union is the union of Set1 and Set2.
ord_union/4 | True iff ord_union(Set1, Set2, Union) and ord_subtract(Set2, Set1, New).

### F.2.20 library(persistency)

current_persistent_predicate/1 | True if PI is a predicate that provides access to the persistent database DB.
db_attach/2 | Use File as persistent database for the calling module.
db_attached/1 | True if the context module attached to the persistent database File.
db_detach/0 | Detach persistency from the calling module and delete all persistent clauses from the Prolog database.
db_sync/1 | Synchronise database with the associated file.
db_sync_all/1 | Sync all registered databases.
persistent/1 | Declare dynamic database terms.

### F.2.21 library(predicate_options)

assert_predicate_options/4 | As predicate_options(:PI, +Arg, +Options).
check_predicate_option/3 | Verify predicate options at runtime.
check_predicate_options/0 | Analyse loaded program for erroneous options.
current_option_arg/2 | True when Arg of PI processes predicate options.
current_predicate_option/3 | True when Arg of PI processes Option.
current_predicate_options/3 | True when Options is the current active option declaration for PI on Arg.
derive_predicate_options/0 | Derive new predicate option declarations.
derived_predicate_options/1 | Derive predicate option declarations for a module.
derived_predicate_options/3 | Derive option arguments using static analysis.
predicate_options/3 | Declare that the predicate PI processes options on Arg.
retractall_predicate_options/0 | Remove all dynamically (derived) predicate options.

### F.2.22 library(prologpack)

environment/2 | Hook to define the environment for building packs.
pack_info/1 | Print more detailed information about Pack.
pack_install/1 | Install a package.
pack_install/2 | Install package Name.
pack_list/1 | Query package server and installed packages and display results.
pack_list_installed/0 | List currently installed packages.
pack_property/2 | True when Property is a property of Pack.
pack_rebuild/0 | Rebuild foreign components of all packages.
pack_rebuild/1 | Rebuilt possible foreign components of Pack.
pack_remove/1 | Remove the indicated package.
pack_search/1 | Query package server and installed packages and display results.
pack_upgrade/1 | Try to upgrade the package Pack.
pack_url_file/2 | True if File is a unique id for the referenced pack and version.

### F.2.23 library(prologxref)

prolog:called_by/2 | (hook) Extend cross-referencer
xref_built_in/1 | Examine defined built-ins
xref_called/3 | Examine called predicates
xref_clean/1 | Remove analysis of source
xref_current_source/1 | Examine cross-referenced sources
xref_defined/3 | Examine defined predicates
xref_exported/2 | Examine exported predicates
xref_module/2 | Module defined by source
xref_source/1 | Cross-reference analysis of source

### F.2.24 library(pairs)

group_pairs_by_key/2 | Group values with equivalent (==/2) consecutive keys.
map_list_to_pairs/3 | Create a Key-Value list by mapping each element of List.
pairs_keys/2 | Remove the values from a list of Key-Value pairs.
pairs_keys_values/3 | True if Keys holds the keys of Pairs and Values the values.
pairs_values/2 | Remove the keys from a list of Key-Value pairs.
transpose_pairs/2 | Swap Key-Value to Value-Key.

### F.2.25 library(pio)

#### F.2.25.1 library(pure_input)

phrase_from_file/2 | Process the content of File using the DCG rule Grammar.
phrase_from_file/3 | As phrase_from_file/2, providing additional Options.
phrase_from_stream/2 | Run Grammer against the character codes on Stream.
stream_to_lazy_list/2 | Create a lazy list representing the character codes in Stream.
lazy_list_character_count//1 | True when CharCount is the current character count in the Lazy list.
lazy_list_location//1 | Determine current (error) location in a lazy list.
syntax_error//1 | Throw the syntax error Error at the current location of the input.

### F.2.26 library(random)

getrand/1 | Query/set the state of the random generator.
maybe/0 | Succeed/fail with equal probability (variant of maybe/1).
maybe/1 | Succeed with probability P, fail with probability 1-P.
maybe/2 | Succeed with probability K/N (variant of maybe/1).
random/1 | Binds R to a new random float in the _open_ interval (0.0,1.0).
random/3 | Generate a random integer or float in a range.
random_between/3 | Binds R to a random integer in [L,U] (i.e., including both L and U).
random_member/2 | X is a random member of List.
random_perm2/4 | Does X=A,Y=B or X=B,Y=A with equal probability.
random_permutation/2 | Permutation is a random permutation of List.
random_select/3 | Randomly select or insert an element.
randseq/3 | S is a list of K unique random integers in the range 1..N.
randset/3 | S is a sorted list of K unique random integers in the range 1..N.
setrand/1 | Query/set the state of the random generator.

### F.2.27 library(readutil)

read_line_to_codes/2 | Read line from a stream
read_line_to_codes/3 | Read line from a stream
read_stream_to_codes/2 | Read contents of stream
read_stream_to_codes/3 | Read contents of stream
read_file_to_codes/3 | Read contents of file
read_file_to_terms/3 | Read contents of file to Prolog terms

### F.2.28 library(record)

record/1 | Define named fields in a term

### F.2.29 library(registry)

This library is only available on Windows systems.

registry_get_key/2 | Get principal value of key
registry_get_key/3 | Get associated value of key
registry_set_key/2 | Set principal value of key
registry_set_key/3 | Set associated value of key
registry_delete_key/1 | Remove a key
shell_register_file_type/4 | Register a file-type
shell_register_dde/6 | Register DDE action
shell_register_prolog/1 | Register Prolog

### F.2.30 library(simplex)

assignment/2 | Solve assignment problem
constraint/3 | Add linear constraint to state
constraint/4 | Add named linear constraint to state
constraint_add/4 | Extend a named constraint
gen_state/1 | Create empty linear program
maximize/3 | Maximize objective function in to linear constraints
minimize/3 | Minimize objective function in to linear constraints
objective/2 | Fetch value of objective function
shadow_price/3 | Fetch shadow price in solved state
transportation/4 | Solve transportation problem
variable_value/3 | Fetch value of variable in solved state

### F.2.31 library(ugraphs)

vertices_edges_to_ugraph/3 | Create unweighted graph
vertices/2 | Find vertices in graph
edges/2 | Find edges in graph
add_vertices/3 | Add vertices to graph
del_vertices/3 | Delete vertices from graph
add_edges/3 | Add edges to graph
del_edges/3 | Delete edges from graph
transpose_ugraph/2 | Invert the direction of all edges
neighbors/3 | Find neighbors of vertice
neighbours/3 | Find neighbors of vertice
complement/2 | Inverse presense of edges
compose/3 |
top_sort/2 | Sort graph topologically
top_sort/3 | Sort graph topologically
transitive_closure/2 | Create transitive closure of graph
reachable/3 | Find all reachable vertices
ugraph_union/3 | Union of two graphs

### F.2.32 library(url)

file_name_to_url/2 | Translate between a filename and a file:`//` URL.
global_url/3 | Translate a possibly relative URL into an absolute one.
http_location/2 | Construct or analyze an HTTP location.
is_absolute_url/1 | True if URL is an absolute URL.
parse_url/2 | Construct or analyse a URL.
parse_url/3 | Similar to parse_url/2 for relative URLs.
parse_url_search/2 | Construct or analyze an HTTP search specification.
set_url_encoding/2 | Query and set the encoding for URLs.
url_iri/2 | Convert between a URL, encoding in US-ASCII and an IRI.
www_form_encode/2 | En/decode to/from application/x-www-form-encoded.

### F.2.33 library(www_browser)

www_open_url/1 | Open a web-page in a browser

### F.2.34 library(solution_sequences)

distinct/1 | True if Goal is true and no previous solution of Goal bound Witness to the same value.
distinct/2 | True if Goal is true and no previous solution of Goal bound Witness to the same value.
group_by/4 | Group bindings of Template that have the same value for By.
limit/2 | Limit the number of solutions.
offset/2 | Ignore the first Count solutions.
order_by/2 | Order solutions according to Spec.
reduced/1 | Similar to distinct/1, but does not guarantee unique results in return for using a limited amount of memory.
reduced/3 | Similar to distinct/1, but does not guarantee unique results in return for using a limited amount of memory.

### F.2.35 library(thread_pool)

create_pool/1 | Hook to create a thread pool lazily.
current_thread_pool/1 | True if Name refers to a defined thread pool.
thread_create_in_pool/4 | Create a thread in Pool.
thread_pool_create/3 | Create a pool of threads.
thread_pool_destroy/1 | Destroy the thread pool named Name.
thread_pool_property/2 | True if Property is a property of thread pool Name.

### F.2.36 library(varnumbers)

max_var_number/3 | True when Max is the max of Start and the highest numbered $VAR(N) term.
numbervars/1 | Number variables in Term using $VAR(N).
varnumbers/2 | Inverse of numbervars/1.
varnumbers/3 | Inverse of numbervars/3.
varnumbers_names/3 | If Term is a term with numbered and named variables using the reserved term '$VAR'(X), Copy is a copy of Term where each '$VAR'(X) is consistently replaced by a fresh variable and Bindings is a list `X = Var`, relating the `X` terms with the variable it is mapped to.

### F.2.37 library(yall)

//2 | Shorthand for `Free/[]`>>`Lambda`.
//3 | Shorthand for `Free/[]`>>`Lambda`.
//4 | Shorthand for `Free/[]`>>`Lambda`.
//5 | Shorthand for `Free/[]`>>`Lambda`.
//6 | Shorthand for `Free/[]`>>`Lambda`.
//7 | Shorthand for `Free/[]`>>`Lambda`.
//8 | Shorthand for `Free/[]`>>`Lambda`.
//9 | Shorthand for `Free/[]`>>`Lambda`.
>>/2 | Calls a copy of Lambda.
>>/3 | Calls a copy of Lambda.
>>/4 | Calls a copy of Lambda.
>>/5 | Calls a copy of Lambda.
>>/6 | Calls a copy of Lambda.
>>/7 | Calls a copy of Lambda.
>>/8 | Calls a copy of Lambda.
>>/9 | Calls a copy of Lambda.
is_lambda/1 | True if Term is a valid Lambda expression.
lambda_calls/2 | Goal is the goal called if call/N is applied to LambdaExpression, where ExtraArgs are the additional arguments to call/N.
lambda_calls/3 | Goal is the goal called if call/N is applied to LambdaExpression, where ExtraArgs are the additional arguments to call/N.