- swipl
- library
- error.pl
- debug.pl -- Print debug messages and test assertions
- apply.pl -- Apply predicates on a list
- lists.pl -- List Manipulation
- broadcast.pl
- predicate_options.pl -- Access and analyse predicate options
- shlib.pl
- option.pl -- Option list processing
- thread_pool.pl
- gensym.pl -- Generate unique symbols
- settings.pl
- arithmetic.pl
- main.pl
- readutil.pl -- Read utilities
- operators.pl -- Manage operators
- pairs.pl -- Operations on key-value lists
- prolog_source.pl -- Examine Prolog source-files
- quasi_quotations.pl -- Define Quasi Quotation syntax
- url.pl -- Analysing and constructing URL
- www_browser.pl -- Open a URL in the users browser
- prolog_colour.pl
- record.pl -- Access compound arguments by name
- prolog_xref.pl -- Prolog cross-referencer data collection
- occurs.pl -- Finding and counting sub-terms
- ordsets.pl -- Ordered set manipulation
- assoc.pl -- Binary associations
- ugraphs.pl -- Graph manipulation library
- iostream.pl -- Utilities to deal with streams
- atom.pl -- Operations on atoms
- prolog_pack.pl -- A package manager for Prolog
- solution_sequences.pl -- Modify solution sequences
- git.pl -- Run GIT commands
- ctypes.pl -- Character code classification
- utf8.pl -- UTF-8 encoding/decoding on lists of character codes.
- base64.pl -- Base64 encoding and decoding
- persistency.pl -- Provide persistent dynamic predicates
- pure_input.pl -- Pure Input from files and streams
- nb_set.pl -- Non-backtrackable sets
- aggregate.pl -- Aggregation operators on backtrackable predicates
- csv.pl -- Process CSV (Comma-Separated Values) data
- dialect.pl -- Support multiple Prolog dialects
- apply_macros.pl -- Goal expansion rules to avoid meta-calling
- yall.pl -- Lambda expressions
- prolog_code.pl -- Utilities for reasoning about code
- dif.pl -- The dif/2 constraint
- thread.pl -- High level thread primitives
- rbtrees.pl -- Red black trees
- nb_rbtrees.pl -- Non-backtrackable operations on red black trees
- random.pl -- Random numbers
- sandbox.pl -- Sandboxed Prolog code
- prolog_format.pl -- Analyse format specifications
- pprint.pl -- Pretty Print Prolog terms
- modules.pl -- Module utility predicates
- lazy_lists.pl -- Lazy list handling
- edinburgh.pl -- Some traditional Edinburgh predicates
- prolog_clause.pl -- Get detailed source-information about a clause
- prolog_breakpoints.pl -- Manage Prolog break-points
- dicts.pl -- Dict utilities
- backcomp.pl -- Backward compatibility
- date.pl -- Process dates and times
- listing.pl -- List programs and pretty print clauses
- prolog_profile.pl -- Execution profiler
- quintus.pl -- Quintus compatibility
- shell.pl -- Elementary shell commands
- intercept.pl -- Intercept and signal interface
- wfs.pl -- Well Founded Semantics interface
- tables.pl -- XSB interface to tables
- system.pl -- System utilities
- threadutil.pl -- Interactive thread utilities
- optparse.pl -- command line parsing
- make.pl -- Reload modified source files
- writef.pl -- Old-style formatted write
- prolog_stack.pl -- Examine the Prolog stack
- prolog_versions.pl -- Demand specific (Prolog) versions
- terms.pl -- Term manipulation
- prolog_jiti.pl -- Just In Time Indexing (JITI) utilities
- files.pl
- prolog_trace.pl -- Print access to predicates
- tty.pl -- Terminal operations
- varnumbers.pl -- Utilities for numbered terms
- prolog_debug.pl -- User level debugging tools
- check.pl -- Consistency checking
- portray_text.pl -- Portray text
- ansi_term.pl -- Print decorated text to ANSI consoles
- heaps.pl -- heaps/priority queues
- strings.pl -- String utilities
- charsio.pl -- I/O on Lists of Character Codes
- edit.pl -- Editor interface
- zip.pl -- Access resource ZIP archives
- prolog_history.pl -- Per-directory persistent commandline history
- prolog_config.pl -- Provide configuration information
- streams.pl -- Manage Prolog streams
- statistics.pl -- Get information about resource usage
- codesio.pl -- I/O on Lists of Character Codes
- prolog_metainference.pl -- Infer meta-predicate properties
- prolog_coverage.pl -- Coverage analysis tool
- fastrw.pl -- Fast reading and writing of terms
- sort.pl
- qsave.pl -- Save current program as a state or executable
- prolog_autoload.pl -- Autoload all dependencies
- macros.pl -- Macro expansion
- help.pl -- Text based manual
- prolog_codewalk.pl -- Prolog code walker
- win_menu.pl -- Console window menu
- base32.pl -- Base32 encoding and decoding
- when.pl -- Conditional coroutining
- increval.pl -- Incremental dynamic predicate modification
- explain.pl -- Describe Prolog Terms
- coinduction.pl -- Co-Logic Programming
- prolog_wrap.pl -- Wrapping predicates
- hashtable.pl -- Hash tables
- oset.pl -- Ordered set manipulation
- library
- foreach(:Generator, :Goal)
- True when the conjunction of instances of Goal created from
solutions for Generator is true. Except for term copying, this could
be implemented as below.
foreach(Generator, Goal) :- findall(Goal, Generator, Goals), maplist(call, Goals).
The actual implementation uses findall/3 on a template created from the variables shared between Generator and Goal. Subsequently, it uses every instance of this template to instantiate Goal, call Goal and undo only the instantiation of the template and not other instantiations created by running Goal. Here is an example:
?- foreach(between(1,4,X), dif(X,Y)), Y = 5. Y = 5. ?- foreach(between(1,4,X), dif(X,Y)), Y = 3. false.
The predicate foreach/2 is mostly used if Goal performs backtrackable destructive assignment on terms. Attributed variables (underlying constraints) are an example. Another example of a backtrackable data structure is in library(hashtable). If we care only about the side effects (I/O, dynamic database, etc.) or the truth value of Goal, forall/2 is a faster and simpler alternative. If Goal instantiates its arguments it is will often fail as the argument cannot be instantiated to multiple values. It is possible to incrementally grow an argument:
?- foreach(between(1,4,X), member(X, L)). L = [1,2,3,4|_].
Note that SWI-Prolog up to version 8.3.4 created copies of Goal using copy_term/2 for each iteration, this makes the current implementation unable to properly handle compound terms (in Goal's arguments) that share variables with the Generator. As a workaround you can define a goal that does not use compound terms, like in this example:
mem(E,L) :- % mem/2 hides the compound argument from foreach/2 member(r(E),L). ?- foreach( between(1,5,N), mem(N,L)).