library

Prolog files

aggregate.pl  -- Aggregation operators on backtrackable predicates
ansi_term.pl  -- Print decorated text to ANSI consoles
apply.pl
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 an ensemble of m (0 <= m <= 4) lists of length n head-to-tail ("fold-left"), using columns of m list elements as arguments for Goal.
foldl/5	Fold an ensemble of m (0 <= m <= 4) lists of length n head-to-tail ("fold-left"), using columns of m list elements as arguments for Goal.
foldl/6	Fold an ensemble of m (0 <= m <= 4) lists of length n head-to-tail ("fold-left"), using columns of m list elements as arguments for Goal.
foldl/7	Fold an ensemble of m (0 <= m <= 4) lists of length n head-to-tail ("fold-left"), using columns of m list elements as arguments for Goal.
include/3	Filter elements for which Goal succeeds.
maplist/2	True if Goal is successfully applied on all matching elements of the list.
maplist/3	True if Goal is successfully applied on all matching elements of the list.
maplist/4	True if Goal is successfully applied on all matching elements of the list.
maplist/5	True if Goal is successfully applied on all matching elements of the list.
partition/4	Filter elements of List according to Pred.
partition/5	Filter List according to Pred in three sets.
scanl/4	Scan an ensemble of m (0 <= m <= 4) lists of length n head-to-tail ("scan-left"), using columns of m list elements as arguments for Goal.
scanl/5	Scan an ensemble of m (0 <= m <= 4) lists of length n head-to-tail ("scan-left"), using columns of m list elements as arguments for Goal.
scanl/6	Scan an ensemble of m (0 <= m <= 4) lists of length n head-to-tail ("scan-left"), using columns of m list elements as arguments for Goal.
scanl/7	Scan an ensemble of m (0 <= m <= 4) lists of length n head-to-tail ("scan-left"), using columns of m list elements as arguments for Goal.
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
base32.pl  -- Base32 encoding and decoding
base64.pl
base64/2	Equivalent to base64_encoded/3 using the options as(atom) and encoding(iso_latin_1).
base64/3	Encode/decode list of character codes using base64.
base64_encoded/3	General the base64 encoding and decoding.
base64_encoded/4
base64url/2	Translates between plaintext and base64url encoded atom or string.
base64url/3	Encode/decode list of character codes using Base64URL.
broadcast.pl  -- Event service
charsio.pl  -- I/O on Lists of Character Codes
check.pl  -- Consistency checking
codesio.pl
format_to_codes/3	Use format/2 to write to a list of character codes.
format_to_codes/4	Use format/2 to write to a difference list of character codes.
open_codes_stream/2	Open Codes as an input stream.
read_from_codes/2	Read Codes into Term.
read_term_from_codes/3	Read Codes into Term.
with_output_to_codes/2	Run Goal with as once/1.
with_output_to_codes/3	Run Goal with as once/1.
with_output_to_codes/4	As with_output_to_codes/3, but Stream is unified with the temporary stream.
write_term_to_codes/3	True when Codes is a string that matches the output of write_term/3 using Options.
write_term_to_codes/4	True when Codes\Tail is a difference list containing the character codes that matches the output of write_term/3 using Options.
write_to_codes/2	Codes is a list of character codes produced by write/1 on Term.
write_to_codes/3	Codes is a difference-list of character codes produced by write/1 on Term.
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
dif/2	Constraint that expresses that Term1 and Term2 never become identical (==/2).
edinburgh.pl
debug/0	Switch on/off debug mode.
display/1	Write a term, ignoring operators and special syntax constructs such as brace terms ({a}) and lists ([a,b,c]).
display/2	Write a term, ignoring operators and special syntax constructs such as brace terms ({a}) and lists ([a,b,c]).
fileerrors/2	Query and change the fileerrors flag.
nodebug/0	Switch on/off debug mode.
reconsult/1	Load source file(s), wiping the old content first.
unknown/2	Edinburgh Prolog predicate for dealing dealing with undefined procedures.
edit.pl
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
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
explain/1	Give an explanation on Term.
explain/2	True when Explanation is an explanation of Term.
fastrw.pl  -- Fast reading and writing of terms
files.pl
gensym.pl  -- Generate unique symbols
git.pl  -- Run GIT commands
hashtable.pl
ht_del/3	Delete Key-Value from HT.
ht_gen/3	True when Key-Value is in HT.
ht_get/3	True when Key is in HT and associated with Value.
ht_is_hashtable/1	True when HT is a hash table.
ht_keys/2	True when Keys is an ordered set of all keys in HT.
ht_new/1	Create a new hash table.
ht_pairs/2	True when Pairs and HT represent the same association.
ht_put/3	Add a Key-Value to HT.
ht_put/5	Add Key-Value to HT.
ht_put_new/3	As ht_put/3, but fails if Key is already in HT instead of updating the associated value.
ht_size/2	True when Size is the number of key-value pairs in HT.
ht_update/4	True when HT holds Key-Old before and Key-New after this call.
heaps.pl  -- heaps/priority queues
help.pl  -- Text based manual
increval.pl
incr_directly_depends/2	True if Goal1 depends on Goal2 in the IDG.
incr_invalid_subgoals/1	List is a sorted list (set) of the incremental subgoals that are currently invalid.
incr_invalidate_call/1	This is the XSB name, but the manual says incr_invalidate_calls/1 and the comment with the code suggests this is misnamed.
incr_invalidate_calls/1	Invalidate all tables for subgoals of Goal as well as tables that are affected by these.
incr_is_invalid/1	True when Subgoal's table is marked as invalid.
incr_propagate_calls/1	Activate the monotonic answer propagation similarly to when a new fact is asserted for a monotonic dynamic predicate.
incr_table_update/0	Updated all invalid tables.
incr_trans_depends/2	True for each pair in the transitive closure of incr_directly_depends(G1, G2).
is_incremental_subgoal/1	This predicate non-deterministically unifies Subgoal with incrementally tabled subgoals that are currently table entries.
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
expand_macros/5	Perform macro expansion on TermIn with layout PosIn to produce TermOut with layout PosOut.
include_macros/3	Include macros from another module.
macro_position/1	True when Position is the position of the macro.
main.pl
argv_options/3	Parse command line arguments.
argv_options/4	As argv_options/3 in guided mode, Currently this version allows parsing argument options throwing an exception rather than calling halt/1 by passing an empty list to ParseOptions.
argv_usage/1	Use print_message/2 to print a usage message at Level.
cli_debug_opt_help/2	Implements opt_type/3, opt_help/2 and opt_meta/2 for debug arguments.
cli_debug_opt_meta/2	Implements opt_type/3, opt_help/2 and opt_meta/2 for debug arguments.
cli_debug_opt_type/3	Implements opt_type/3, opt_help/2 and opt_meta/2 for debug arguments.
cli_enable_development_system/0	Re-enable the development environment.
cli_parse_debug_options/2	Parse certain commandline options for debugging and development purposes.
main/0	Call main/1 using the passed command-line arguments.
make.pl  -- Reload modified source files
make/0	Reload all source files that have been changed since they were loaded.
make_reload_file/1	Reload file into the proper module.
modules.pl  -- Module utility predicates
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
pop_operators/0	Revert all changes to the operator table realised since the last push_operators/1.
pop_operators/1	Reset operators as pushed by push_operators/2.
push_op/3	As op/3, but this call must appear between push_operators/1 and pop_operators/0.
push_operators/1	Installs the operators from New, where New is a list of op(Prec, Type, :Name).
push_operators/2	Installs the operators from New, where New is a list of op(Prec, Type, :Name).
option.pl  -- Option list processing
optparse.pl  -- command line parsing
ordsets.pl  -- Ordered set manipulation
oset.pl  -- Ordered set manipulation
pairs.pl  -- Operations on key-value lists
persistency.pl  -- Provide persistent dynamic predicates
pio.pl  -- Pure I/O
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  -- Utilities for reasoning about code
prolog_codewalk.pl
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
debug_control_hook/1	Allow user-hooks in the Prolog debugger interaction.
debugging/0	Report current status of the debugger.
debugging_hook/1	Multifile hook that is called as forall(debugging_hook(DebugMode), true) and that may be used to extend the information printed from other debugging libraries.
exception_hook/5	Trap exceptions and consider whether or not to start the tracer.
nospy/1	Set/clear spy-points.
nospyall/0	Set/clear spy-points.
notrap/1	Install a trap on error(Formal, Context) exceptions that unify.
spy/1	Set/clear spy-points.
trap/1	Install a trap on error(Formal, Context) exceptions that unify.
trap_alias/2	Define short hands for commonly used exceptions.
prolog_format.pl  -- Analyse format specifications
prolog_history.pl  -- Per-directory persistent commandline 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 properties
prolog_pack.pl  -- A package manager for Prolog
prolog_profile.pl  -- Execution profiler
prolog_source.pl
quasi_quotation_syntax/2	True when the quasi quotation syntax Syntax can be loaded from Library.
xref_close_source/2	Called by prolog_close_source/1 to close a source previously opened by the hook prolog:xref_open_source/2.
xref_open_source/2	Hook to open an xref SourceID.
directory_source_files/3	True when Files is a sorted list of Prolog source files in Dir.
file_alias_path/2	True if file Alias points to Dir.
file_name_on_path/2	True if OnPath a description of File based on the file search path.
load_quasi_quotation_syntax/2	Import quasi quotation syntax Syntax from Path into the module specified by the first argument.
path_segments_atom/2	Translate between a path represented as a/b/c and an atom representing the same path.
prolog_canonical_source/2	Given a user-specification of a source, generate a unique and indexable identifier for it.
prolog_close_source/1	Close a stream opened using prolog_open_source/2.
prolog_file_directives/3	True when Directives is a list of directives that appear in the source file File.
prolog_open_source/2	Open source with given canonical id (see prolog_canonical_source/2) and remove the #!
prolog_read_source_term/4	Read a term from a Prolog source-file.
read_source_term_at_location/3	Try to read a Prolog term form an arbitrary location inside a file.
requires_library/2	known expansion hooks.
valid_term_position/2	Check that a Term has an appropriate TermPos layout.
prolog_stack.pl  -- Examine the Prolog stack
prolog_trace.pl  -- Print access to predicates
prolog_versions.pl  -- Demand specific (Prolog) versions
prolog_wrap.pl
current_predicate_wrapper/4	True if Head is wrapped with Body.
unwrap_predicate/2	Remove the outermost wrapper whose name unifies with Name.
wrap_predicate/4	Wrap the predicate referenced by Head using Body.
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_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
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
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
sandbox_allowed_directive/1	Throws an exception if G is not considered a safe directive.
sandbox_allowed_expansion/1	Throws an exception if G is not considered a safe expansion goal.
sandbox_allowed_goal/1	Throw an exception if it is not safe to call G.
format_calls/3	Find ~@ calls from Format and Args.
safe_call/1	Call Goal if it complies with the sandboxing rules.
safe_directive/1	Hook to declare additional directives as safe.
safe_global_variable/1	Declare the given global variable safe to write to.
safe_goal/1	True if calling Goal provides no security risc.
safe_meta/2	Hook.
safe_primitive/1	True if Goal is safe to call (i.e., cannot access dangerous system-resources and cannot upset other parts of the Prolog process).
safe_prolog_flag/2	True if it is safe to set the flag Flag to Value.
settings.pl
convert_setting_text/3	Converts from textual form to Prolog Value.
current_setting/1	True if Setting is a currently defined setting.
env/2	Evaluate environment variables on behalf of arithmetic expressions.
env/3	Evaluate environment variables on behalf of arithmetic expressions.
list_settings/0	List settings to current_output.
list_settings/1	List settings to current_output.
load_settings/1	Load local settings from File.
load_settings/2	Load local settings from File.
restore_setting/1	Restore the value of setting Name to its default.
save_settings/0	Save modified settings to File.
save_settings/1	Save modified settings to File.
set_setting/2	Change a setting.
set_setting_default/2	Change the default for a setting.
setting/2	True when Name is a currently defined setting with Value.
setting/4	Define a setting.
setting_property/2	Query currently defined settings.
shell.pl  -- Elementary shell commands
cd/0	Change working directory.
cd/1	Change working directory.
dirs/0	Manage the directory stack:.
file_style/2	True when File should be listed as a terminal hyperlink.
ls/0	Listing similar to Unix =ls -F=, flagging directories with =/=.
ls/1	Listing similar to Unix =ls -F=, flagging directories with =/=.
mv/2	Move (Rename) a file.
popd/0	Manage the directory stack:.
pushd/0	Manage the directory stack:.
pushd/1	Manage the directory stack:.
pwd/0	Print current working directory.
rm/1	Remove (unlink) a file.
shell/0	Execute an interactive shell.
shlib.pl  -- Utility library for loading foreign objects (DLLs, shared objects)
solution_sequences.pl
call_nth/2	True when Goal succeeded for the Nth time.
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.
sort.pl
statistics.pl  -- Get information about resource usage
streams.pl
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
terms.pl  -- Term manipulation
thread.pl  -- High level thread primitives
call_in_thread/2	Run Goal as an interrupt in the context of Thread.
concurrent/3	Run Goals in parallel using N threads.
concurrent_and/2	Concurrent version of (Generator,Test).
concurrent_and/3	Concurrent version of (Generator,Test).
concurrent_forall/2	True when Action is true for all solutions of Generate.
concurrent_forall/3	True when Action is true for all solutions of Generate.
concurrent_maplist/2	Concurrent version of maplist/2.
concurrent_maplist/3	Concurrent version of maplist/2.
concurrent_maplist/4	Concurrent version of maplist/2.
first_solution/3	Try alternative solvers concurrently, returning the first answer.
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 debug-mode, trapping the graphical debugger on reaching spy-points or errors.
tdebug/1	Enable debug-mode, trapping the graphical debugger on reaching spy-points or errors.
thread_has_console/0	True when the calling thread has an attached console.
threads/0	List currently known threads with their status.
tnodebug/0	Disable debug-mode in all threads or the specified Thread.
tnodebug/1	Disable debug-mode in all threads or the specified Thread.
tprofile/1	Profile the operation of Thread until the user hits a key.
tspy/1	Trap the graphical debugger on reaching Spec in the specified or any thread.
tspy/2	Trap the graphical debugger on reaching Spec in the specified or any thread.
with_stopped_threads/2	Stop all threads except the caller while running once(Goal).
tty.pl  -- Terminal operations
ugraphs.pl  -- Graph manipulation library
url.pl  -- Analysing and constructing URL
utf8.pl  -- UTF-8 encoding/decoding on lists of character codes.
varnumbers.pl
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.
wfs.pl  -- Well Founded Semantics interface
when.pl
when/2	Execute Goal when Condition is satisfied.
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