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The Design and Implementation
of the
Lout Document Formatting Language
Jeffrey H. Kingston
Basser Department of Computer Science,
The University of Sydney 2006,
Australia
27 January, 1993
1. Introduction
Lout [1, 2] is a high-level language for document formatting, designed and implemented by
the author. The implementation, known as Basser Lout, is a fully operational production version
written in C for the Unix operating system,1 which translates Lout source code into PostScript,2
a device-independent graphics rendering language accepted by many high-resolution output
devices, including most laser printers. Basser Lout is available free of charge [3]. It includes
installation instructions, C source, seven standard packages, and complete documentation in the
form of six technical reports and a manual page.
The Lout project arose out of the author’s desire to bring to document formatting languages
the elegance of expression found in programming languages like Algol-60 and Pascal. This emphasis on expressiveness has produced an order of magnitude reduction in the cost of developing
document formatting applications. For example, an equation formatting application, which may
be difficult or impossible to add to other systems, can be written in Lout in a few days.
When expert users can implement such applications quickly, non-experts benefit. Although
Lout itself provides only a small kernel of carefully chosen primitives, packages written in Lout
and distributed with Basser Lout provide an unprecedented array of advanced features in a form
accessible to non-expert users. The features include rotation and scaling, fonts, paragraph and
page breaking, displays and lists, floating figures and tables, footnotes, chapters and sections (automatically numbered), running page headers and footers, odd-even page layouts, automatically
generated tables of contents, sorted indexes and reference lists, bibliographic and other databases
(including databases of formats for printing references), equations, tables, diagrams, formatting
of Pascal programs, and automatically maintained cross references.
This paper charts the evolution of Lout from conception in mid-1984 to the public
release of Basser Lout in October 1991. Lout is organized around four key concepts – objects,
definitions, galleys, and cross references – and they were developed in the order listed, so this
paper will treat each in turn, discussing its design, implementation, problems, and prospects for
1
Unix is a trademark of AT&T Bell Laboratories.
PostScript is a trademark of Adobe Systems, Incorporated.
2