## Unofficial Texinfo Format

This is the second edition SICP book,
from Unofficial Texinfo Format.

You are probably reading it in an Info hypertext browser, such as the Info mode of Emacs. You might alternatively be reading it TeX-formatted on your screen or printer, though that would be silly. And, if printed, expensive.

The freely-distributed official HTML-and-GIF format was first converted personally to Unofficial Texinfo Format (UTF) version 1 by Lytha Ayth during a long Emacs lovefest weekend in April, 2001.

The UTF is easier to search than the HTML format. It is also much more accessible to people running on modest computers, such as donated ’386-based PCs. A 386 can, in theory, run Linux, Emacs, and a Scheme interpreter simultaneously, but most 386s probably can’t also run both Netscape and the necessary X Window System without prematurely introducing budding young underfunded hackers to the concept of thrashing. UTF can also fit uncompressed on a 1.44MB floppy diskette, which may come in handy for installing UTF on PCs that do not have Internet or LAN access.

The Texinfo conversion has been a straight transliteration, to the extent possible. Like the TeX-to-HTML conversion, this was not without some introduction of breakage. In the case of Unofficial Texinfo Format, figures have suffered an amateurish resurrection of the lost art of ASCII. Also, it’s quite possible that some errors of ambiguity were introduced during the conversion of some of the copious superscripts (‘^’) and subscripts (‘_’). Divining which has been left as an exercise to the reader. But at least we don’t put our brave astronauts at risk by encoding the greater-than-or-equal symbol as <u>&gt;</u>.

If you modify sicp.texi to correct errors or improve the ASCII art, then update the @set utfversion 2.andresraba6.6 line to reflect your delta. For example, if you started with Lytha’s version 1, and your name is Bob, then you could name your successive versions 1.bob1, 1.bob2, … 1.bobn. Also update utfversiondate. If you want to distribute your version on the Web, then embedding the string “sicp.texi” somewhere in the file or Web page will make it easier for people to find with Web search engines.

It is believed that the Unofficial Texinfo Format is in keeping with the spirit of the graciously freely-distributed HTML version. But you never know when someone’s armada of lawyers might need something to do, and get their shorts all in a knot over some benign little thing, so think twice before you use your full name or distribute Info, DVI, PostScript, or PDF formats that might embed your account or machine name. Peath, Lytha Ayth

Addendum: See also the SICP video lectures by Abelson and Sussman: at MIT CSAIL or MIT OCW.

Second Addendum: Above is the original introduction to the UTF from 2001. Ten years later, UTF has been transformed: mathematical symbols and formulas are properly typeset, and figures drawn in vector graphics. The original text formulas and ASCII art figures are still there in the Texinfo source, but will display only when compiled to Info output. At the dawn of e-book readers and tablets, reading a PDF on screen is officially not silly anymore. Enjoy! A.R, May, 2011

Third Addendum: Things go in spirals. We explored the powers of Texinfo and LaTeX at typesetting the PDF book. Now it’s time to come back to HTML. This turn it shall be HTML5. “It can be a dangerous place, but it’s our last, best hope for peace.” (Sinclair, Babylon 5.) Does the peace endure after the browser wars? Anyway, the aim of the project is to approach the quality of LaTeX output by using the HTML5 toolbox. JavaScript, CSS3, SVG, MathJax, MathML, and web fonts are employed here. Due to the experimental nature of this undertaking, there will be glitches and errors in some browsers. Technical and artistic help is appreciated. In the meantime, enjoy the book, and fire up a REPL! A.R, January, 2014