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![Sample 2 • f[X]=2*X is equivalent to (f[X]==Y) <= (Y==2*x) • Functions return only 1 value per key (aka dict()) • Functions can appear in expressions • Resolution starts with the latest clause, and stops on first answer • Support for aggregate functions : sum, min, max, …](https://image.slidesharecdn.com/logicprogramminginpython-140627095657-phpapp02/75/Logic-programming-in-python-12-2048.jpg)
Uploaded byPierre Carbonnelle
Logic programming in python
Logic programming in Python allows for productive, readable programs using logic rules rather than loops or conditionals. The pyDatalog library adds logic programming capabilities to Python. Programs are defined with facts and clauses like Prolog, and can query SQL databases. PyDatalog memoizes results to avoid recomputation and supports features like aggregate functions. It allows applications like spreadsheet programming, expert systems, and cross-database queries. The presenter outlines roadmaps for adding an equation solver, transactions, and improving performance.
Logic programming in python
- 1. Logic Programming inPython Pierre Carbonnelle FOSDEM 2014
- 2. No if’s, noloops, just the plain mathematical definition !
- 3. Logic programming (Prolog, SQL) Functional (Lisp,..) Imperative / OO (C, Smalltalk)
- 4. Logic programming (Prolog, SQL) Functional (Lisp,..) Imperative / OO (C, Smalltalk) Python Python + pyDatalog
- 5. Why Logic Programmingin Python ? Be productive Be Readable Use AI Easy to learn Batteries included Query 11 SQL databases
- 6. The anatomy ofa prolog program Fact Clause Query
- 7. The anatomy ofa pyDatalog program
- 8. The anatomy ofa pyDatalog program
- 9. Sample 1 Could be writtenin SQL too !
- 10. Sample 1 Loop Calculation Test Input/output polymorphism ! Shorter programs !
- 11. Sample 1 Batteries included Wouldneed an equation solver
- 12. Sample 2 • f[X]=2*Xis equivalent to (f[X]==Y) <= (Y==2*x) • Functions return only 1 value per key (aka dict()) • Functions can appear in expressions • Resolution starts with the latest clause, and stops on first answer • Support for aggregate functions : sum, min, max, …
- 13. Sample 3 Familiartuple notation Memoized Faster Avoid infinite loop
- 14. Sample 4 Prefixed function toquery Python classes or SQL databases
- 15. Other pyDatalog features •Runs on PyPy, Python 2, Python 3 • Accepts predicate definition written in Python • For I/O, performance, … • Thread-safe • For use in multi-threaded web framework • Multi-model : Switch from one Logic model (= set of clauses) to another
- 16. Applications Core technology BenefitApplications The SLG resolution algorithm determines the sequence of steps to resolve a query. Spreadsheet-programming : faster iterations, fewer bugs, more readable. Rule-based expert systems for pricing, tax calculation, access right, robot control, intelligent agent. Input/output polymorphism. Maximise code reuse : shorter program, simpler database query language. Cross-database queries, data integration. Intermediate results are memoized. Avoid re-calculation. Avoid infinite loop. Recursive algorithm on tree or graph structures, natural language processing, code analysis
- 17. Roadmap : Equationsolver
- 18. Roadmap : Transactions •Assert facts within transactions, with possible roll-back • Use logic clauses to validate data operations • Use logic clauses to define triggers (condition => action) • Memoize results across queries within the same transaction • Translate Datalog queries into SQL for server-side processing Feedback, Help welcome !!
- 19. Roadmap : Performance •Rewrite critical sections in C • Exploit multi-threading in resolution engine Feedback, Help welcome !!
- 20. Why Logic Programmingin Python ? Easy to learn Batteries included Query 11 SQL databases Be productive Be Readable Use AI