web-to-html

Conversion of Knuth's WEB to HTML.

Currently only “Phase 1” and “Phase 2” (see a comment I wrote elsewhere) are implemented.

How to use it

Prerequisites: You must have a Common Lisp implementation and ASDF (which likely comes with your Lisp).

First, download the project into a place where ASDF can see it (such as ~/common-lisp/ on *nix). Next, start a Lisp session and do

(require "asdf")
(asdf:load-system "web-to-html")
(in-package :web-to-html)

Now you have the program loaded. The entry point for Phase 1 is the Phase-1 function, which has the following syntax:

(Phase-1 WEB-file [change-file])

where WEB-file and change-file are streams. By default, change-file is (make-string-input-stream ""), i.e., an empty stream. An example usage would be

(with-open-file (input "tex.web")
  (Phase-1 input))

After executing the above expression, you can use the following functions to inspect the collected data:

• (get-nth-section n) returns the representation of the nth section.
• (section-text section) returns the token list associated with a section object.
• (lookup-module name) returns the module object corresponding to the module named name.
• (lookup-prefix prefix) returns the module object uniquely identified by the given prefix (don't include “...”).
• (module-name module) returns the name associated with a given module object.
• (module-definitions module) returns a list of section numbers where the given module is defined.
• (map-modules function) calls the function on each module. They are traversed in tree order, but you shouldn't depend on this.

To get the full text of a module module, you might run

(let ((definitions (module-definitions module)))
  (loop for definition in definitions
        appending (section-Pascal-part (get-nth-section definition))))

Running Phase 2 is easier; all you need to do is evaluate (Phase-2), provided that Phase 1 has already completed. However, most of Knuth's programs will need to be changed, because they have meta-comments (@{…@}) that confuse Phase 2. For WEAVE and TANGLE it suffices to remove the reference to the “Compiler directives” module, and the 'BREAKPOINT' comment in TeX's debug_help must also be removed.

Weird stuff

Here are some things you might notice about the code:

• There are no abbreviations, except when the abbreviation is a single character long. This is a stylistic preference.
• Comments use the “incorrect” quotation marks `` and ''. I would just write “ and ”, but I've decided to make the program Unicode-agnostic, and I can't bear the sight of ".
• The condition system isn't used for errors in Phase 1. Eventually there will be a whole heirarchy of condition types, but for now errors are simply reported.
• There is a mysterious :long-distance token type, apparently corresponding to an @n control code. This is intended to be used to specify the section in which an identifier should be identified, in case it is ambiguous.