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PDDL parser

Project description


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pddl aims to be an unquestionable and complete parser for PDDL 3.1.


  • from PyPI:
pip install pddl
  • from source (main branch):
pip install git+
  • or, clone the repository and install:
git clone
cd pddl
pip install .


You can use the pddl package in two ways: as a library, and as a CLI tool.

As a library

This is an example of how you can build a PDDL domain or problem programmatically:

from pddl.logic import Predicate, constants, variables
from pddl.core import Domain, Problem
from pddl.action import Action
from pddl.formatter import domain_to_string, problem_to_string
from pddl.requirements import Requirements

# set up variables and constants
x, y, z = variables("x y z", types=["type_1"])
a, b, c = constants("a b c", type_="type_1")

# define predicates
p1 = Predicate("p1", x, y, z)
p2 = Predicate("p2", x, y)

# define actions
a1 = Action(
    parameters=[x, y, z],
    precondition=p1(x, y, z) & ~p2(y, z),
    effect=p2(y, z)

# define the domain object.
requirements = [Requirements.STRIPS, Requirements.TYPING]
domain = Domain("my_domain",
                types={"type_1": None},
                constants=[a, b, c],
                predicates=[p1, p2],


that gives:

(define (domain my_domain)
    (:requirements :strips :typing)
    (:types type_1)
    (:constants a b c - type_1)
    (:predicates (p1 ?x - type_1 ?y - type_1 ?z - type_1)  (p2 ?x - type_1 ?y - type_1))
    (:action action-1
        :parameters (?x - type_1 ?y - type_1 ?z - type_1)
        :precondition (and (p1 ?x ?y ?z) (not (p2 ?y ?z)))
        :effect (p2 ?y ?z)

As well as a PDDL problem:

problem = Problem(
    objects=[a, b, c],
    init=[p1(a, b, c), ~p2(b, c)],
    goal=p2(b, c)


(define (problem problem-1)
    (:domain my_domain)
    (:requirements :strips :typing)
    (:objects a b c - type_1)
    (:init (not (p2 b c)) (p1 a b c))
    (:goal (p2 b c))

Example parsing:

from pddl import parse_domain, parse_problem
domain = parse_domain('d.pddl')
problem = parse_problem('p.pddl')

As CLI tool

The package can also be used as a CLI tool. Supported commands are:

  • pddl domain FILE: validate a PDDL domain file, and print it formatted.
  • pddl problem FILE: validate a PDDL problem file, and print it formatted.


Supported PDDL 3.1 requirements:

  • :strips
  • :typing
  • :negative-preconditions
  • :disjunctive-preconditions
  • :equality
  • :existential-preconditions
  • :universal-preconditions
  • :quantified-preconditions
  • :conditional-effects
  • :fluents
  • :numeric-fluents
  • :non-deterministic (see 6th IPC: Uncertainty Part)
  • :adl
  • :durative-actions
  • :duration-inequalities
  • :derived-predicates
  • :timed-initial-literals
  • :preferences
  • :constraints
  • :action-costs


If you want to contribute, here's how to set up your development environment.

  • Install Pipenv
  • Clone the repository: git clone && cd pddl
  • Install development dependencies: pipenv shell --python 3.8 && pipenv install --dev


To run tests: tox

To run only the code tests: tox -e py37

To run only the code style checks: tox -e flake8


To build the docs: mkdocs build

To view documentation in a browser: mkdocs serve and then go to http://localhost:8000



pddl is released under the MIT License.

Copyright (c) 2021-2022 WhiteMech


The pddl project is partially supported by the ERC Advanced Grant WhiteMech (No. 834228), the EU ICT-48 2020 project TAILOR (No. 952215), the PRIN project RIPER (No. 20203FFYLK), and the JPMorgan AI Faculty Research Award "Resilience-based Generalized Planning and Strategic Reasoning".

Change Log

0.1.0 (2021-06-21)

The first official release of pddl.

Main features:

  • Specify PDDL domains and problems programmatically.
  • Parsing for PDDL domains and problems.

0.0.1 (2020-07-30)

  • First commit on the package.

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