repository·master·Indexed 22 days ago
https://github.com/swi-prolog/swipl-develAn open-source (BSD-2) implementation of the Prolog language with extensive extensions. It supports applications in NLP, robotics, machine learning, and web development via WASM. The documentation covers CLI application creation using library(main), environment personalization via init.pl, XSB dialect support, and manual generation using LaTeX and PlDoc.
Specific scripts are provided for MacOS-related build tasks:
macos-deps.sh: Builds MacOS dependencies required for releases.macosx_bundle_fixup.sh: A helper used by CPack to finalize dependencies within a MacOS bundle.library(sicstus) provides a compatibility layer for users migrating from or working with SICStus Prolog. It allows you to run code written for SICStus within the SWI-Prolog environment by providing equivalent predicates and behaviors.For an enhanced development experience, you can use several GUI and editor-integrated tools:
swipl-win executable, which opens a Prolog terminal. XPCE also provides PceEmacs, an Emacs clone featuring a rich Prolog mode, a source-level debugger, and profiling tools. XPCE is included in default binaries for Windows, MacOS, and as a flatpak for Linux.The following scripts are used for managing SWI-Prolog releases:
newversion: Updates version files and GIT tags.mkchangelog [--no-date] [version]: Generates the changelog.make-distribution: Must be sourced. Defines functions to build and upload a release. This script may require manual editing when used on external build machines.make-src-tape: Creates a .tar.gz file from the GIT repo and its submodules. Typically invoked via make-distribution.labeling/2 or label/1.The CLP(FD) library allows you to use constraints instead of low-level arithmetic predicates like is/2 or =:=/2. This provides greater flexibility, allowing you to reorder goals and improve termination properties. For example, using #=/2 allows a predicate to work even when some arguments are not yet instantiated, which is not possible with standard arithmetic.
n_factorial(0, 1).
n_factorial(N, F) :-
N #> 0,
N1 #= N - 1,
F #= N * F1,
n_factorial(N1, F1).In CLP(B), you can construct Boolean expressions using the following syntax:
| Operator | Meaning |
|---|---|
0 | false |
1 | true |
_variable_ | unknown truth value |
_atom_ | universally quantified variable |
~ Expr | logical NOT |
Expr + Expr | logical OR |
Expr * Expr | logical AND |
Expr # Expr | exclusive OR (XOR) |
Var ^ Expr | existential quantification |
Expr =:= Expr | equality |
Expr \= Expr | disequality (same as #) |
Expr =< Expr | implication (less or equal) |
Expr >= Expr | greater or equal |
Expr < Expr | less than |
Expr > Expr | greater than |
card(Is, Exprs) | cardinality constraint: true if the number of true expressions in Exprs is a member of the list Is (which can contain integers or ranges like From-To) |
+(Exprs) | n-fold disjunction (OR of all elements) |
*(Exprs) | n-fold conjunction (AND of all elements) |
Atoms represent parametric values that are universally quantified. In residual goals, these typically appear on the right-hand side of equations to express functional dependencies on input variables.
An association list is a collection of unique keys associated with values.
Key constraints and properties:
Advantages:
The primary advantage of CLP(FD) constraints is their relational nature. Low-level predicates like is/2 or =:=/2 require all arguments to be sufficiently instantiated, whereas CLP(FD) constraints can be used to solve for unknown variables in any direction.
Example: Solving for a variable
Using CLP(FD):
?- 3 #= Y+2.
Y = 1.Using low-level arithmetic (fails):
?- 3 is Y+2.
ERROR: is/2: Arguments are not sufficiently instantiated
?- 3 =:= Y+2.
ERROR: =:=/2: Arguments are not sufficiently instantiated?- 3 #= Y+2.
Y = 1.The SWI-Prolog manual is built from *.doc files which are converted to LaTeX via the doc2tex program.
pl.sty allows underscores to be used without special precautions outside math mode. Do NOT write expand\_file/2; simply write expand_file/2.doc2tex uses a URL quoting mechanism (sequences named \S<name>).Every described predicate MUST have an entry in the summary.doc file. Note that the content of summary.doc is ordered alphabetically.
SWI-Prolog provides two distinct tracing features:
trace/0, spy/1 (in debug mode), or set_breakpoint/4 (in debug mode).visible/1 to control console output and leash/1 to control which ports cause pauses.notrace/0 stops tracing; nodebug/0 stops all debugging.trace/1 or trace/2.visible/1 or leash/1; ports are explicitly defined via trace/2.