CL-DOCUTILS: Docutils for Common Lisp

AuthorDr John A.R. Williams
created:22 September 2009
Copyright© 2009 J.A.R. Williams


CL-DOCUTILS is a Common Lisp implementation of the Docutils text processing system for processing plaintext into presentational formats such as HTML and LaTeX. It is based upon the Python Docutils reference implementation but uses Common Lisp idioms making it easier to extend and more flexible. As with the reference implementation it includes a parser for the reStructured text plaintext markup syntax which is suitable for marking up documentation and for use as user markup for collaborative web sites. It is successfully used to support a higher education peer-review assessment and online tutorial system.

Table of Contents

Download and Installation

CL-DOCUTILS together with this documentation can be downloaded from the git repository at <git://> or from <>. The current version is 0.1.5.

CL-DOCUTILS comes with a system definition for ASDF and is compiled and loaded in the usual way. It depends upon CL-DATA-FORMAT-VALIDATION and CL-PPCRE . It has been developed and tested using SBCL but should be portable to any ANSI-compliant implementation of Common Lisp.

CL-DOCUTILS is made available under the terms of the GPL v3 license -- see the file LICENSE.txt for details.


For questions, bug reports, feature requests, improvements, or patches relating to this implementation please email <>.

See reStructured text for the wide range of documentation on the restructured text syntax and Docutils for information on the reference implementation on which this is based.

Convenience Functions For Users

Although this is intended as a library for embedding in other applications the following functions in the DOCUTILS package are provided as examples suitable for direct use:

API For Developers

This documentation is in early stages and those wishing to use the library are encouraged to read the documentation for the Python Docutils implementation to get a flavour and examine the code here to determine differences. The generic interface is largely defined and documented in the file publisher.lisp which is a good place to start. Queries to the author as mentioned under support are also welcome.

Data Flow

The following diagram shows the components and data flow:

             /               \
            /                 \


Specialised methods of the API are already provided for stream, pathname and string source types. It is the responsibility of the source and output streams to handle external character encodings.

  • generic function new-document source => document

    Implementations of this should create a new document instance with the appropriate non-default document settings from source.

    The default method loads no settings and the method specialised on pathname source will load settings from *standard-config-files* and cl-docutils.conf in the pathname directory.

  • generic function read-lines source => vector

    Given a source, return a vector of the text lines from source for subsequent parsing.

  • generic function settings source => hash-table

    Return a hash table of processing settings to be associated with documents with this source.

  • function register-settings-spec specifications => specifications

    Register a list of setting specifications. Each entry corresponds to one setting and has the form (name type default description) where name is a keyword symbol used to look up that setting, type the data format validation type specification, default a default value to be used if unspecified and description a string description suitable for users.

    Specifications are normally given in text files in internet header style with the setting name, followed by a colon, followed by the textual representation of the value. Continuation lines are supported.


  • generic function read-document source reader => document

    Read a document from source using reader and using the transforms associated with this reader return a fully parsed and transformed document.

The following restructured text specific API is exported from package docutils.parser.rst.

  • class rst-reader

    Class name of the standard restructured text parser.

  • macro def-role ((name textvar &rest argument-list) &body body)

    Define a new interpreted role element handler for role with canonical name name. textvar is the name of the variable holding the textual argument to be referenced in body and argument-list is as follows:

    lambda-list::= ({var | (var [[specializer] [default]])}*
                   [{{&content {var [[specializer] [default]]}}] )

    body is the list of forms which should return a docutils:text node instance to be substituted into the document

  • macro def-directive ((name parent &rest argument-list) &body body)

    Define a new directive element handler with name name. Similar to def-role except the body is responsible for adding nodes to the parent node.


  • generic function transforms reader => list

    Return a list of transform specifications (class names) to be applied by this reader after parsing.

  • generic function transform transform

    Evaluate the given transform instance on its node.

  • generic function do-transforms transforms document => document

    Apply a list of transformation to the document in priority order.


  • class writer

    Base class for all writer instances.

  • generic function visit-node writer node

    Process the node updating writer parts accordingly. Visiting a document node will clear all document parts first.

  • generic function write-document writer document destination

    Use writer to visit the document and write all parts in order to destination

  • generic function write-part writer part destination

    Write a given named document part from a writer to destination.

  • generic function settings writer => settings

    Return an alist of settings associated with this specific writer instance which will override the document settings during writer processing.

  • macro with-part ((part-name) &body) => result

    Specify dynamically the document part to be written to using part-append and part-prepend.

  • function part-append &rest values

    function part-prepend &rest values

    These function append or prepend their arguments to the currently set part of the current writer.

  • class docutils.writer.html:html-writer

    The base class for writing a document out in html format. The provided file docutils.css provides an example style sheet for the generated documents.

  • class docutils.writer.latex:latex-writer

    The base class for writing a document out in latex format. The provided file docutils.tex should be placed in the latex search path as it is required by the produced latex documents.


  • variable *unknown-reference-resolvers*

    List of functions to try to resolve unknown references during the transformation process. This can usefully be set to, for example, check against a database of pages in a live online system and return the relevant reference into the document.

  • variable *standard-config-files*

    List of pathnames to files to be parsed in order for document configuration settings. Defaults include /etc/cl-docutils.conf and  /.cl-docutils.conf. A pathname source will also check for cl-docutils.conf file in the same directory.

  • variable *default-reader-package*

    Value to bind *package* to when reading lisp forms from the document.

  • variable *evaluator*

    Name of function to use to evaluate lisp forms in evaluateable nodes/

  • variable *evaluation-error-hook*

    Function to be called if there are errors when calling *evaluator*

Differences from Reference Implementation

Character Sets
This Common Lisp implementation uses standard Lisp string handling and the CL-PPCRE regular expression library. Character set translation on input and output is orthogonal to this processing and can be formed using the appropriate specialised stream libraries such as FlexiStreams.
Nested Inline Elements
This implementation supports nested inline elements (where they make sense) whereas the reference implementation did not.
Error Messages
Error messages is handled differently in this implementation with the result that they may not be located in exactly the same position relative the cause as in the Python implementation.
Python Enhancement Proposals
Parsing of Python Enhancement Proposals (PEPs) is not supported as these have significance only for the Python community, however PEP references are supported as to enable the use of the stand-alone test documents provided with the reference Python implementation.


A fundamental requirement and important feature of restructured text is that it can easily be customised and extended for use in embedded applications (particularly web applications) without changing the core language. Restructured text was explicitly designed with this in mind, however the Common Lisp implementation is quite different, and more powerful in this regard than the reference Python implementation.

The major feature for language extension at the block level is by the use of the named directive explicit markup. New directives can be defined using the def-directive macro.
Roles provide a means of implementing new inline elements. They are defined using the def-role macro.
Transformations are associated with the parser element. If you wish new transformations to be run, use a subclass of the parser which return the appropriate list of transformations.

Additional Elements

  • role math

    This role allows the embedding of mathematical expressions using LaTeX syntax. An implict syntax, delimiting the argument with '$$' is also provided.

  • directive equation

    This directive allows the embedding of equations in LaTeX format.

  • role eval

    A role allowing the embedding of inline evaluateable expressions in Lisp syntax

  • directive evaluation

    A directive allowing embedding of expressions to be evaluated - Currently only Lisp expressions are supported.


The many contributers to the original Docutils project on which this based and the many examples of code made available by Common Lisp community which have inspired and taught me. Particular mention should go to Edi Weitz for making available the CL-PPCRE used here and the Flex-Streams library which can be used to deal with external character coding issue.