library

Prolog files

aggregate.pl  -- Aggregation operators on backtrackable predicates
ansi_term.pl  -- Print decorated text to ANSI consoles
apply.pl  -- Apply predicates on a list
apply_macros.pl  -- Goal expansion rules to avoid meta-calling
apply_macros_sentinel/0	Used to detect that library(apply_macros) is loaded into the current context explicitly.
expand_phrase/2	Provide goal-expansion for PhraseGoal.
expand_phrase/4	Provide goal-expansion for PhraseGoal.
arithmetic.pl  -- Extensible arithmetic
assoc.pl  -- Binary associations
atom.pl
identifier_parts/2	Parts is a list of atoms that make up Identifier.
join_identifier_parts/3	Join parts of an identifier according to Style.
restyle_identifier/3	Restyle an identifier by extracting the alnum substrings and joining them together according to Style.
backcomp.pl  -- Backward compatibility
$apropos_match/2	True if Needle is a sub atom of Haystack.
$arch/2
$argv/1
$declare_module/3	Used in triple20 particle library.
$home/1
$module/2
$set_prompt/1	Set the prompt for the toplevel.
$sig_atomic/1	Execute Goal without processing signals.
$strip_module/3	This used to be an internal predicate.
$version/1
C/3	Used to be generated by DCG.
at_initialization/1	Register goal only to be run if a saved state is restored.
call_cleanup/3	Call Cleanup with an indication of the reason unified to Catcher.
checklist/2
concat/3
concat_atom/2	Concatenate a list of atomic values to an atom.
concat_atom/3	Concatenate a list of atomic values to an atom, inserting Separator between each consecutive elements.
convert_time/2	Convert a time-stamp as obtained though get_time/1 into a textual representation using the C-library function ctime().
convert_time/8	Convert a time stamp, provided by get_time/1, time_file/2, etc.
current_module/2	True if Module is a module loaded from File.
current_mutex/3
current_thread/2
displayq/1	Write term ignoring operators and quote atoms.
displayq/2	Write term ignoring operators and quote atoms.
eval_license/0
export_list/2	Module exports the predicates of List.
feature/2	Control Prolog flags.
flush/0
free_variables/2	Return a list of unbound variables in Term.
hash/1	Demands PredInd to be indexed using a hash-table.
hash_term/2	If Term is ground, Hash is unified to an integer representing a hash for Term.
index/1	Prepare the predicate indicated by Head for multi-argument indexing.
lock_predicate/2
merge/3	Merge the ordered sets List1 and List2 into a new ordered list.
merge_set/3	Merge the ordered sets Set1 and Set2 into a new ordered set without duplicates.
message_queue_size/2	True if Queue holds Size terms.
proper_list/1	Old SWI-Prolog predicate to check for a list that really ends in a [].
read_clause/1
read_clause/2
read_history/6
read_pending_input/3
read_variables/2
read_variables/3
set_base_module/1	Set the default module from which we inherit.
set_feature/2	Control Prolog flags.
setup_and_call_cleanup/3	Call Cleanup once after Goal is finished.
setup_and_call_cleanup/4	Call Cleanup once after Goal is finished, with Catcher unified to the reason.
sformat/2
sformat/3
string_to_atom/2	Bi-directional conversion between string and atom.
string_to_list/2	Bi-directional conversion between a string and a list of character codes.
sublist/3	Succeeds if List2 unifies with a list holding those terms for which call(Goal, Elem) succeeds.
substring/4	Predecessor of sub_string using 1-based Offset.
sumlist/2	True when Sum is the list of all numbers in List.
thread_at_exit/1	Register Goal to be called when the calling thread exits.
trie_insert_new/3
unlock_predicate/2
write_length/3
write_ln/1
base32.pl  -- Base32 encoding and decoding
base64.pl  -- Base64 encoding and decoding
broadcast.pl  -- Event service
charsio.pl  -- I/O on Lists of Character Codes
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.
check.pl  -- Consistency checking
check_installation.pl  -- Check installation issues and features
check_config_files/0	Examines the locations of config files.
check_installation/0	Check features of the installed system.
check_installation/1	As check_installation/0, but additionally returns a list of Component-Problem pairs.
test_installation/0	Run regression tests in the installed system.
test_installation/1	Run regression tests in the installed system.
update_config_files/0	Move config files from their old location to the new if the file or directory exists in the old location but not in the new.
codesio.pl  -- I/O on Lists of Character Codes
coinduction.pl  -- Co-Logic Programming
csv.pl  -- Process CSV (Comma-Separated Values) data
ctypes.pl  -- Character code classification
is_digit/3	Succeeds if `C' is a digit using `Base' as base and `Weight' represents its value.
is_paren/2	True if Open is the open-parenthesis of Close.
to_lower/2	Downcase a character code.
to_upper/2	Upcase a character code.
upper_lower/2	True when U is the character code of an uppercase character and L is the character code of the corresponding lowercase character.
date.pl  -- Process dates and times
debug.pl  -- Print debug messages and test assertions
dialect.pl  -- Support multiple Prolog dialects
dicts.pl  -- Dict utilities
dif.pl  -- The dif/2 constraint
edinburgh.pl  -- Some traditional Edinburgh predicates
edit.pl
addr2location/3	Get the File and Line for a C address.
edit/0	Edit associated or script file.
edit/1	Edit indicated object.
edit_command/2	This predicate should specify the shell-command called to invoke the user's editor.
locate/2	Locate object from the specified location.
locate/3
locations/2	Locate entities matching Spec.
predicate_location/2	Find the source location of a predicate.
select_location/3
error.pl
current_encoding/1	True if Name is the name of a supported encoding.
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	Culprit is of the correct type and correct domain, but there is no existing (external) resource of type ObjectType that is represented by it.
existence_error/3	Culprit is of the correct type and correct domain, but there is no existing (external) resource of type ObjectType that is represented by it in the provided set.
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 Operation on (whatever is represented by) Culprit that is of the given PermissionType (in fact, the ISO Standard is confusing and vague about these terms' meaning).
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 Culprit is not of the expected ValidType.
uninstantiation_error/1	An argument is over-instantiated.
exceptions.pl
catch/4	As catch/3, only catching exceptions for which exception(ErrorType,Ball) is true.
error_term/2	Describe the formal part of error(Formal,ImplDefined) exceptions.
exception/2	If Ball is unbound, adds a delayed goal that tests the error belongs to Type when Ball is instantiated (by catch/3).
exception_term/2	Describe exceptions that are not error(Formal, _) terms.
exception_type/2	Declare all exceptions subsumed by Term to be an exception of Type.
explain.pl  -- Describe Prolog Terms
fastrw.pl  -- Fast reading and writing of terms
files.pl
can_open_file/2	Succeeds if the user has access to `File' in mode `Mode'.
chdir/1	Change Working Directory.
gensym.pl  -- Generate unique symbols
git.pl  -- Run GIT commands
hashtable.pl  -- Hash tables
heaps.pl  -- heaps/priority queues
help.pl
tty_link_hook/2	Open a man: or apropos: link that was clicked in an Epilog Terminal.
apropos/1	Print objects from the manual whose name or summary match with Query.
apropos/2	Print objects from the manual whose name or summary match with Query.
help/0	Show help for What.
help/1	Show help for What.
help_apropos/4	Find matching documented objects in the help database.
help_text/2	When Predicate is a term of the form Name/Arity for which documentation exists, HelpText is the documentation in textual format (parsed from the HTML help).
show_html_hook/1	Hook called to display the extracted HTML document.
increval.pl  -- Incremental dynamic predicate modification
intercept.pl  -- Intercept and signal interface
iostream.pl  -- Utilities to deal with streams
close_any/1	Execute the Close closure returned by open_any/5.
open_any/5	Establish a stream from Specification that should be closed using Close, which can either be called or passed to close_any/1.
lazy_lists.pl  -- Lazy list handling
listing.pl  -- List programs and pretty print clauses
lists.pl  -- List Manipulation
macros.pl  -- Macro expansion
main.pl  -- Provide entry point for scripts
make.pl  -- Reload modified source files
modules.pl
current_temporary_module/1	True when we are executing in the given temporary module context.
in_temporary_module/3	Run Goal on temporary loaded sources and discard the module and loaded predicates after completion.
nb_rbtrees.pl
nb_rb_get_node/3	True if Node is the node in RBTree associated to Key.
nb_rb_insert/3	Add Key-Value to the tree RBTree using non-backtrackable destructive assignment.
nb_rb_node_value/2	Value is the value associated to Node.
nb_rb_set_node_value/2	Associate Value with Node.
nb_set.pl  -- Non-backtrackable sets
add_nb_set/2	Insert Key into the set.
add_nb_set/3	Insert Key into the set.
empty_nb_set/1	Create an empty non-backtrackable set.
gen_nb_set/2	Enumerate the members of a set in the standard order of terms.
nb_set_to_list/2	Get the elements of a an nb_set.
size_nb_set/2	Unify Size with the number of elements in the set.
occurs.pl  -- Finding and counting sub-terms
operators.pl  -- Manage operators
option.pl  -- Option list processing
optparse.pl  -- command line parsing
ordsets.pl  -- Ordered set manipulation
oset.pl
oset_addel/3	Ordered set element addition.
oset_delel/3	Ordered set element deletion.
oset_diff/3	Ordered set difference.
oset_dint/2	Distributed intersection.
oset_dunion/2	Distributed union.
oset_int/3	ordered set intersection.
oset_is/1	check that OSet in correct format (standard order).
oset_power/2	True when PSet is the powerset of Set.
oset_union/3	Union is the union of OSet1 and OSet2.
pairs.pl  -- Operations on key-value lists
persistency.pl  -- Provide persistent dynamic predicates
portray_text.pl
portray_text/1	Switch portraying on or off.
set_portray_text/2	Set options for portraying.
set_portray_text/3	Set options for portraying.
pprint.pl  -- Pretty Print Prolog terms
predicate_options.pl  -- Access and analyse predicate options
prolog_autoload.pl  -- Autoload all dependencies
prolog_breakpoints.pl  -- Manage Prolog break-points
prolog_clause.pl
clause_info/4	Fetches source information for the given clause.
clause_info/5	Fetches source information for the given clause.
clause_name/2	Provide a suitable description of the indicated clause.
initialization_layout/4	Find term-layout of :- initialization directives.
make_varnames/5	Create a Term varnames(...) where each argument contains the name of the variable at that offset.
open_source/2	Hook into clause_info/5 that opens the stream holding the source for a specific clause.
predicate_name/2	Describe a predicate as [Module:]Name/Arity.
unify_goal/5	This hook is called to fix up source code manipulations that result from goal expansions.
unify_term/2	Unify the two terms, where T2 is created by writing the term and reading it back in, but be aware that rounding problems may cause floating point numbers not to unify.
prolog_code.pl
body_term_calls/2	True when BodyTerm calls Goal.
comma_list/2	True if CommaList is a nested term over the ','/2 (';'/2) functor and List is a list expressing the elements of the conjunction.
extend_goal/3	Extend the possibly qualified Goal0 with additional arguments from Extra.
head_name_arity/3	Similar to functor/3, but deals with SWI-Prolog's zero-argument callable terms and avoids creating a non-callable term if Name is not an atom and Arity is zero.
is_control_goal/1	True if Goal is a compiled Prolog control structure.
is_predicate_indicator/1	True when Term is a predicate indicator.
mkconj/3	Create a conjunction or disjunction from two terms.
mkdisj/3	Create a conjunction or disjunction from two terms.
most_general_goal/2	General is the most general version of Goal.
pi_head/2	Translate between a PredicateIndicator and a Goal term.
predicate_label/2	Create a human-readable label for the given predicate indicator.
predicate_sort_key/2	Key is the (module-free) name of the predicate for sorting purposes.
semicolon_list/2	True if CommaList is a nested term over the ','/2 (';'/2) functor and List is a list expressing the elements of the conjunction.
prolog_codewalk.pl  -- Prolog code walker
prolog_program_clause/2	True when ClauseRef is a reference for clause in the program.
prolog_walk_code/1	Walk over all loaded (user) Prolog code.
subterm_pos/5	True when SubTerm is a sub term of Term, compared using Cmp, TermPosition describes the term layout of Term and SubTermPos describes the term layout of SubTerm.
prolog_colour.pl  -- Prolog syntax colouring support.
prolog_config.pl
prolog_config/2	Get information on the configuration of the current Prolog system.
prolog_dump_runtime_variables/0	Dump the current configuration in shell format.
prolog_coverage.pl  -- Coverage analysis tool
prolog_debug.pl  -- User level debugging tools
prolog_format.pl  -- Analyse format specifications
prolog_history.pl
prolog_history/1	Execute Action on the history.
prolog_jiti.pl
jiti_list/0	List the JITI (Just In Time Indexes) of selected predicates.
jiti_list/1	List the JITI (Just In Time Indexes) of selected predicates.
jiti_suggest_modes/0	Propose modes for the predicates referenced by Spec.
jiti_suggest_modes/1	Propose modes for the predicates referenced by Spec.
prolog_metainference.pl
infer_meta_predicate/2	True when MetaSpec is a meta-predicate specifier for the predicate Head.
inferred_meta_predicate/2	True when MetaSpec is an inferred meta-predicate specification for Head.
prolog_pack.pl  -- A package manager for Prolog
prolog_profile.pl  -- Execution profiler
prolog_source.pl  -- Examine Prolog source-files
prolog_stack.pl  -- Examine the Prolog stack
prolog_trace.pl  -- Print access to predicates
prolog_versions.pl  -- Demand specific (Prolog) versions
prolog_wrap.pl  -- Wrapping predicates
prolog_xref.pl
called_by/2	If this succeeds, the cross-referencer assumes Goal may call any of the goals in ListOfCalled.
called_by/4	True when Called is a list of callable terms called from Goal, handled by the predicate Module:Goal and executed in the context of the module Context.
hook/1	True if Goal is a hook that is called spontaneously (e.g., from foreign code).
meta_goal/2	Define meta-predicates.
xref_called/3	True when By is called from Called in Source.
xref_called/4	True when By is called from Called in Source.
xref_called/5	True when By is called from Called in Source.
xref_clean/1	Reset the database for the given source.
xref_comment/3	Is true when Source has a section comment with Title and Comment.
xref_comment/4	Is true when Head in Source has the given PlDoc comment.
xref_current_source/1	Check what sources have been analysed.
xref_defined/3	Test if Goal is accessible in Source.
xref_definition_line/2	If the 3th argument of xref_defined contains line info, return this in Line.
xref_done/2	Cross-reference executed at Time.
xref_exported/2	True when Source exports Head.
xref_hook/1	Definition of known hooks.
xref_meta/2	True when Called is a list of terms called from Head.
xref_meta/3	True when Head calls Called in Source.
xref_mode/3	Is true when Source provides a predicate with Mode and determinism.
xref_module/2	True if Module is defined in Source.
xref_object_comment/4	Is true when Object in Source has the given PlDoc comment.
xref_object_signature/3	Is true when Object in Source has Signature as provided by the hook doc_compile_comment/5.
xref_op/2	Give the operators active inside the module.
xref_option/2	True when Source was processed using Option.
xref_prolog_flag/4	True when Flag is set to Value at Line in Source.
xref_public_list/3	Find meta-information about File.
xref_public_list/4	Find meta-information about File.
xref_public_list/6	Find meta-information about File.
xref_public_list/7	Find meta-information about File.
xref_source/1	Generate the cross-reference data for Source if not already done and the source is not modified.
xref_source/2	Generate the cross-reference data for Source if not already done and the source is not modified.
xref_source_file/3	Find named source file from Spec, relative to Src.
xref_source_file/4	Find named source file from Spec, relative to Src.
xref_uses_file/3	True when Source tries to load a file using Spec.
pure_input.pl  -- Pure Input from files and streams
qpforeign.pl
load_foreign_files/0	Calls make_foreign_wrapper_file(+File), compiles the wrapper and loads the predicates.
load_foreign_files/2	Calls make_foreign_wrapper_file(+File), compiles the wrapper and loads the predicates.
load_foreign_files/3	Calls make_foreign_wrapper_file(+File), compiles the wrapper and loads the predicates.
load_foreign_resource/2	Load a foreign module.
make_foreign_resource_wrapper/3	Create a wrapper-file for the given foreign resource.
make_foreign_wrapper_file/1	Just output the wrapper file to the named .c file.
make_foreign_wrapper_file/2	Just output the wrapper file to the named .c file.
make_shared_object/3	Generate a wrapper and link it using plld to the given SharedObject.
qsave.pl
arch_shlib/3	This is a user defined hook called by qsave_program/2.
qsave_program/1	Make a saved state in file `File'.
qsave_program/2	Make a saved state in file `File'.
qsave_toplevel/0	Called to handle `-c file` compilaton.
quasi_quotations.pl  -- Define Quasi Quotation syntax
quintus.pl  -- Quintus compatibility
random.pl  -- Random numbers
rbtrees.pl  -- Red black trees
is_rbtree/1	True if Term is a valid Red-Black tree.
list_to_rbtree/2	Tree is the red-black tree corresponding to the mapping in List, which should be a list of Key-Value pairs.
ord_list_to_rbtree/2	Tree is the red-black tree corresponding to the mapping in list List, which should be a list of Key-Value pairs.
rb_apply/4	If the value associated with key Key is Val0 in Tree, and if call(G,Val0,ValF) holds, then NewTree differs from Tree only in that Key is associated with value ValF in tree NewTree.
rb_clone/3	`Clone' the red-back tree TreeIn into a new tree TreeOut with the same keys as the original but with all values set to unbound values.
rb_del_max/4	Delete the largest element from the tree Tree, returning the key Key, the value Val associated with the key and a new tree NewTree.
rb_del_min/4	Delete the least element from the tree Tree, returning the key Key, the value Val associated with the key and a new tree NewTree.
rb_delete/3	Delete element with key Key from the tree Tree, returning the value Val associated with the key and a new tree NewTree.
rb_delete/4	Same as rb_delete(Tree, Key, NewTree), but also unifies Val with the value associated with Key in Tree.
rb_empty/1	Succeeds if Tree is an empty Red-Black tree.
rb_fold/4	Fold the given predicate over all the key-value pairs in Tree, starting with initial state State0 and returning the final state State.
rb_in/3	True when Key-Value is a key-value pair in red-black tree Tree.
rb_insert/4	Add an element with key Key and Value to the tree Tree creating a new red-black tree NewTree.
rb_insert_new/4	Add a new element with key Key and Value to the tree Tree creating a new red-black tree NewTree.
rb_keys/2	Keys is unified with an ordered list of all keys in the Red-Black tree Tree.
rb_lookup/3	True when Value is associated with Key in the Red-Black tree Tree.
rb_map/2	True if call(Goal, Value) is true for all nodes in T.
rb_map/3	For all nodes Key in the tree Tree, if the value associated with key Key is Val0 in tree Tree, and if call(G,Val0,ValF) holds, then the value associated with Key in NewTree is ValF.
rb_max/3	Key is the maximal key in Tree, and is associated with Val.
rb_min/3	Key is the minimum key in Tree, and is associated with Val.
rb_new/1	Create a new Red-Black tree Tree.
rb_next/4	Next is the next element after Key in Tree, and is associated with Val.
rb_partial_map/4	For all nodes Key in Keys, if the value associated with key Key is Val0 in tree Tree, and if call(G,Val0,ValF) holds, then the value associated with Key in NewTree is ValF, otherwise it is the value associated with the key in Tree.
rb_previous/4	Previous is the previous element after Key in Tree, and is associated with Val.
rb_size/2	Size is the number of elements in Tree.
rb_update/4	Tree NewTree is tree Tree, but with value for Key associated with NewVal.
rb_update/5	Same as rb_update(Tree, Key, NewVal, NewTree) but also unifies OldVal with the value associated with Key in Tree.
rb_visit/2	Pairs is an infix visit of tree Tree, where each element of Pairs is of the form Key-Value.
rb_visit_range/4	Retrieves a range of pairs with keys between Min and Max (inclusive) from a Tree using standard term comparison.
readln.pl
readutil.pl  -- Read utilities
record.pl  -- Access compound arguments by name
rwlocks.pl
with_rwlock/3	Run Goal, synchronized with LockId in ModeSpec.
with_rwlock/4	Run Goal, synchronized with LockId in ModeSpec.
sandbox.pl  -- Sandboxed Prolog code
settings.pl  -- Setting management
shell.pl  -- Elementary shell commands
shlib.pl
compat_arch/2	User definable hook to establish if Arch1 is compatible with Arch2 when running a shared object.
current_foreign_library/2	Query currently loaded shared libraries.
foreign_library_property/2	True when Property is a property of the foreign library File.
load_foreign_library/1	Load a shared object or DLL.
load_foreign_library/2	Load a shared object or DLL.
reload_foreign_libraries/0	Reload all foreign libraries loaded (after restore of a state created using qsave_program/2.
unload_foreign_library/1	Unload a shared object or DLL.
unload_foreign_library/2	Unload a shared object or DLL.
use_foreign_library/1	Load and install a foreign library as load_foreign_library/1,2 and register the installation using initialization/2 with the option now.
use_foreign_library/2	Load and install a foreign library as load_foreign_library/1,2 and register the installation using initialization/2 with the option now.
solution_sequences.pl  -- Modify solution sequences
sort.pl
locale_sort/2	Sort a list of atoms using the current locale.
predsort/3	Sorts similar to sort/2, but determines the order of two terms by calling Compare(-Delta, +E1, +E2).
statistics.pl  -- Get information about resource usage
streams.pl  -- Manage Prolog streams
with_output_to/3	Run Goal and once/1 while capturing all output to all streams (current_output, user_output and user_error) in the string Output.
strings.pl  -- String utilities
system.pl  -- System utilities
tables.pl  -- XSB interface to tables
tableutil.pl  -- Table inspection and statistics utilities
terms.pl  -- Term manipulation
thread.pl  -- High level thread primitives
thread_pool.pl
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.
worker_exitted/3	It is possible that '__thread_pool_manager' no longer exists while closing down the process because the manager was killed before the worker.
threadutil.pl  -- Interactive thread utilities
attach_console/0	Create a new console and make the standard Prolog streams point to it.
attach_console/1	Create a new console and make the standard Prolog streams point to it.
join_threads/0	Join all terminated threads.
tbacktrace/1	Print a backtrace for Thread to the stream user_error of the calling thread.
tbacktrace/2	Print a backtrace for Thread to the stream user_error of the calling thread.
tdebug/0	Enable or disable a thread or group of threads for debugging using the graphical tracer.
tdebug/1	Enable or disable a thread or group of threads for debugging using the graphical tracer.
thread_alias/1	Set the alias for a thread.
thread_has_console/0	True when the calling thread has an attached console.
threads/0	List currently known threads with their status.
tnodebug/0	Enable or disable a thread or group of threads for debugging using the graphical tracer.
tnodebug/1	Enable or disable a thread or group of threads for debugging using the graphical tracer.
tprofile/1	Profile the operation of Thread until the user hits a key.
tspy/1	Trap the graphical debugger on reaching Spec.
tspy/2	Trap the graphical debugger on reaching Spec.
with_stopped_threads/2	Stop all threads except the caller while running once(Goal).
tty.pl
menu/3	Show a menu.
tty_clear/0	Clear the display.
tty_flash/0	Give visual signal if possible, otherwise beep.
ugraphs.pl  -- Graph manipulation library
url.pl  -- Analysing and constructing URL
utf8.pl  -- UTF-8 encoding/decoding on lists of character codes.
varnumbers.pl  -- Utilities for numbered terms
vm.pl
vm_list/1	Lists the definition of the predicates matching Spec to current_output.
wfs.pl  -- Well Founded Semantics interface
when.pl  -- Conditional coroutining
writef.pl  -- Old-style formatted write
www_browser.pl  -- Open a URL in the users browser
yall.pl  -- Lambda expressions
zip.pl  -- Access resource ZIP archives