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Scm2Xexpr - Scheme code formatter

Overview

The program listed below converts Scheme source code, stored in a specified file or text string, into PLT's Xexpr representation of XML. This can be used to generate web pages containing formatted Scheme code. The program listing below is generated by a PLT web servlet which uses this code.

About the code

The code was adapted from Dorai Sitaram's TeX2page, with the following changes:

• The Scheme formatting parts of TeX2page were extracted, and TeX-specific features removed.
• Generation of the HTML output string was changed to generate a list-based Xexpr structure. This enabled the output model to be changed from imperative, to purely functional.
• All mutable global variables were eliminated, to better support concurrent access in the web servlet context.
• The input stream code was decoupled from the formatting code, and wrapped in an input stream interface abstraction. This more directly enables each request to have its own private input stream. The previously global variable *current-input* is now a lexical variable within the input stream code. The result is that concurrent requests can be served safely without resorting to the namespace tricks used by TeX2page as distributed with PLT.

With the exception of side effects encapsulated in the input stream code, and the use of destructive reverse!, for performance reasons, the resulting program is side-effect free.

scm2xexpr.scm

Syntax Highlighting: error: scm: undefined language

scheme-names.scm

Syntax Highlighting: error: scm: undefined language

pretty.scm

The following is a PLT web servlet which invokes the above code:

Syntax Highlighting: error: scm: undefined language