libprolog library

A modern, ISO-compliant Prolog engine for Dart.

libprolog provides a complete Prolog implementation designed for embedding in Dart applications. It supports ISO Prolog core predicates and DCG.

Example usage:

import 'package:libprolog/libprolog.dart';

void main() async {
  // Create a Prolog engine
  final prolog = PrologEngine();

  // Assert facts
  prolog.assertz('parent(tom, bob)');
  prolog.assertz('parent(bob, ann)');

  // Query
  await for (final solution in prolog.query('parent(X, Y)')) {
    print('${solution['X']} is parent of ${solution['Y']}');
  }
}

Classes

AnsiColors: ANSI color codes for syntax highlighting.
Atom: A Prolog atom - an atomic constant.
BuiltinContext: Context provided to built-in predicates during execution.
BuiltinError: Built-in threw an error (ISO exception).
BuiltinFailure: Built-in failed (no solutions).
BuiltinNotFound: Built-in is not recognized (let resolver try database).
BuiltinRegistry: Registry of built-in predicates.
BuiltinResult: Result of executing a built-in predicate.
BuiltinStream: Built-in succeeded with multiple solutions (non-deterministic).
BuiltinSuccess: Built-in succeeded with no choice points (deterministic success).
ByteInputStream: Byte input stream.
ByteOutputStream: Byte output stream.
CatchFrame: Catch frame for ISO exception handling.
CharacterInputStream: Character input stream.
CharacterOutputStream: Character output stream.
ChoicePoint: A choice point for backtracking.
ChoicePointStack: Stack of choice points for backtracking.
Clause: A Prolog clause (fact or rule).
Compound: A Prolog compound term (structure).
Database: A Prolog clause database.
DCGTranslator: Translates a DCG rule into a regular Prolog clause.
FileInputStream: File-based character input stream.
FileOutputStream: File-based character output stream.
Goal: A goal to be proven during execution.
GoalStack: A goal stack representing the current execution state.
Highlighter: Syntax highlighter for Prolog code.
Lexer: ISO-compliant Prolog lexer.
MemoryStorage: In-memory clause storage with first-argument indexing.
Operator: An operator definition.
OperatorTable: Operator table for parser.
Parser: ISO-compliant Prolog parser.
PersistentStorage: Optional interface for storage implementations that support persistence.
PrologEngine: High-level Dart API for the Prolog engine.
PrologFloat: A Prolog floating-point number.
PrologInteger: A Prolog integer number.
PrologNumber: Base class for numeric terms.
PrologStream: Abstract base class for Prolog streams.
QueryResult: Represents the result of a query that expects at most one solution.
Resolver: SLD Resolution engine.
Solution: A solution to a query.
StderrStream: Standard error stream (stderr).
StdinStream: Standard input stream (stdin).
StdoutStream: Standard output stream (stdout).
Storage: Abstract interface for clause storage engines.
StorageStats: Statistics about storage operations (for optimization).
StorageWithStats: Optional interface for storage implementations that support statistics.
StreamManager: Global stream manager for Prolog I/O.
StreamProperties: Properties of a Prolog stream.
Substitution: A substitution (environment) mapping variables to terms.
Term: Base class for all Prolog terms.
TermConversion: Utilities for converting between Dart values and Prolog terms.
Token: A token from the lexer.
Trail: A trail for recording variable bindings during unification.
TransactionalStorage: Optional interface for storage implementations that support transactions.
Unify: Unification algorithm implementing Robinson's algorithm with occur check.
Variable: A Prolog logic variable.

Enums

EndOfStream: End-of-stream status.
OperatorType: Operator associativity and position.
StreamDirection: Direction of a stream.
StreamType: Type of stream content.
TokenType: Token types for Prolog lexer.
TracePort: Trace port types for debugging.

Extensions

SolutionExtensions on Solution: Extension methods for Solution to provide Dart-friendly access.

Functions

createStandardRegistry({StreamManager? streamManager, Database? database}) → BuiltinRegistry: Creates a registry with all standard ISO built-ins registered.
evaluateArithmetic(Term term, Substitution substitution, [String context = 'is/2']) → Term: Evaluates an arithmetic expression to a numeric term.
isDCGRule(Term term) → bool: Helper to check if a clause is a DCG rule.
registerArithmeticBuiltins(BuiltinRegistry registry) → void: Registers ISO Prolog arithmetic built-in predicates.
registerAtomProcessingBuiltins(BuiltinRegistry registry) → void: Registers ISO Prolog atom and string processing built-in predicates.
registerControlBuiltins(BuiltinRegistry registry) → void: Registers control flow built-ins.
registerDatabaseBuiltins(BuiltinRegistry registry, Database database) → void: Registers database manipulation built-ins.
registerDCGBuiltins(BuiltinRegistry registry) → void: Registers DCG built-in predicates.
registerIOBuiltins(BuiltinRegistry registry, StreamManager streamManager) → void: Registers I/O built-in predicates.
registerListPredicates(BuiltinRegistry registry) → void: Registers list manipulation built-ins.
registerMetaPredicates(BuiltinRegistry registry) → void: Registers meta-predicates (all-solutions).
registerTermComparisonBuiltins(BuiltinRegistry registry) → void: Registers ISO Prolog term comparison built-in predicates.
registerTermManipulationBuiltins(BuiltinRegistry registry) → void: Registers ISO Prolog term manipulation built-in predicates.

Typedefs

ArithmeticError = ArithmeticException
BuiltinPredicate = BuiltinResult Function(BuiltinContext context): A built-in predicate implementation.
TraceCallback = bool Function(TracePort port, int depth, Term goal): Callback for trace events.

Exceptions / Errors

ArgumentError: Argument error for invalid API usage (Dart-level).
ArithmeticException: Exception thrown during arithmetic evaluation.
DomainError: ISO 7.2.3.c: Error when argument is out of valid domain.
EvaluationError: ISO 7.2.3.f: Error when evaluation fails.
ExistenceError: ISO 7.2.3.i: Error when predicate does not exist.
InstantiationError: ISO 7.2.3.a: Error when argument is not sufficiently instantiated.
LexerError: Lexer error exception.
ParserError: Parser error for syntax problems.
PermissionError: ISO 7.2.3.h: Error when permission is denied.
PrologException: Base class for all Prolog-related exceptions.
RepresentationError: ISO 7.2.3.e: Error when representation is outside implementation limits.
ResourceError: Resource error when system resource is exhausted.
TypeError: ISO 7.2.3.b: Error when argument is of wrong type.

libprolog library

Classes

Enums

Extensions

Functions

Typedefs

Exceptions / Errors

libprolog package

libprolog library