nrdl

A pure-Python implementation of NRDL, the Nestable, Readable Document Language — a superset of JSON with comments, multi-line strings, and symbols. This package is a port of the reference implementation in Common Lisp, following the language specification and ABNF in the repository README.

Installation

pip install nrdl

Usage

The API follows the json module's conventions: load/dump work with file handles, and loads/dumps work with strings.

import nrdl

# Deserialize an NRDL document from a string.
doc = nrdl.loads("""
{
    the-wind "bullseye"
    the-trees false
    the-sparrows his-eye
}
""")
# -> {"the-wind": "bullseye", "the-trees": false, "the-sparrows": "his-eye"}

# Or from a file handle.
with open("config.nrdl", encoding="utf-8") as fh:
    doc = nrdl.load(fh)

# Serialize Python data back to NRDL.
nrdl.dumps(doc, pretty_indent=4)
# -> '{\n    the-sparrows "his-eye"\n    the-trees false\n    the-wind "bullseye"\n}'

# Write it to a file handle.
with open("config.out.nrdl", "w", encoding="utf-8") as fh:
    nrdl.dump(doc, fh, pretty_indent=4)

# Emit a JSON document instead.
nrdl.dumps(doc, json_mode=True)
# -> '{"the-sparrows": "his-eye", "the-trees": false, "the-wind": "bullseye"}'

Because Python has no symbol type, NRDL symbols deserialize to plain strings, and true/false/null deserialize to True/False/None. When serializing, dictionary keys are written as symbols while string values are written as quoted strings.

Command line

The package also installs an nrdl command that parses documents and prints the parsed data, as NRDL by default or as JSON with --json:

$ nrdl config.nrdl
{
    the-wind "bullseye"
}
$ nrdl --json config.nrdl
{
    "the-wind": "bullseye"
}
$ cat config.nrdl | nrdl
...
$ nrdl --validate config.nrdl && echo ok
ok

nrdl --validate parses documents without printing them, reporting only problems to stderr and exiting non-zero when a document is invalid.

Full documentation is available on ReadTheDocs.