This library contains multiple Common Lisp ASDF systems for manipulating Planning Domain Definition Language (PDDL), and – newly added (summer 2023) – Hierarchical Domain Definition Language (HDDL).
These libraries enable a programmer to parse PDDL and HDDL, generate and modify parsed PDDL and HDDL expressions, and then write these expressions to files for use by AI planners. Constructs handled include domain definitions, problem definitions, and plans.
Two additional special functionalities:
- PDDL-PLANNERS
- Attempts to provide a uniform CL interface to a number of AI planning systems to support automating their use.
- HDDL-JSON
- Provides JSON schemas for HDDL constructs (domains and problems) and code for emitting HDDL domains and problems as JSON. We hope to later provide the same capabilities for PDDL, and also support reading domains and problems as JSON, not just writing them, so that planning models can be authored in JSON as well as in PDDL/HDDL. We believe that this can streamline the development of AI planning by obviating the need to incorporate HDDL and PDDL parsers in planners.
We plan to provide an executable wrapper around these libraries for parsing and translation, which will be available for building – for those comfortable with Common Lisp – or for use through Docker images.
Support for HDDL is as yet only partial. In particular, the library only support totally-ordered subtasks, not partially-ordered ones. We expect to add this shortly. Since we do not ourselves need these constructs, getting it added will be hastened substantially by requests from potential users (or, even more, pull requests)!
This code is made publicly available by SIFT, LLC under the terms of the 3-clause BSD license, attached as license.txt.
This does not provide any PDDL-wrangling functions (well, with the exception of
PPRINT-PDDL, whose job it is to print PDDL readably). It simply provides
the PDDL package, which is a package into which other code can read PDDL
expressions. Having a canonical package for PDDL means that multiple different
bits of code can all wrangle PDDL without getting into package hell. In
particular, it means that one bit of code can read PDDL into an s-expression
that other code can interact with.
PDDL-wrangling functions. These are made to allow you to read and write PDDL files, especially problem files, domain files, and plans. There are also problem and domain constructors, accessors, and modifiers. A key purpose of this library is for programmers to be able to make derivative or templated domains and problems. You can read a problem (domain), set some of its slots programmatically, and then write it out to a file.
This attempts to provide a uniform-ish API to invoke a number of different planners from Common Lisp. This is just the core framework here.
Given a particular planning program that one wants to invoke, one extends the set of planning methods (often adding new keyword arguments) provided here with methods for your new planners.
This approach is only somewhat successful, since we find that planners often have very complex invocation procedures with very particular sets of configuration options.
Playing a role similar to the #PDDL system, this library provides the
HDDL package (Common Lisp namespace) into which HDDL domain can be
parsed.
This is the HDDL-wrangling system proper. It plays an analogous role to the #PDDL-UTILS system.
This system provides the two key interface functions
HDDL-JSON:JSON-DUMP-DOMAIN and HDDL-JSON:JSON-DUMP-PROBLEM which,
as their names suggest, provide the ability to write domains and
problems to JSON files.
This is not a library, but rather a repository of JSON schemas for HDDL as written to JSON.