tangle - translate WEB to Pascal
tangle webfile[.web] [ changefile[.ch] ]
This manual page is not meant to be exhaustive. The complete documentation for this ver-
sion of TeX can be found in the info file or manual Web2C: A TeX implementation.
The tangle program converts a Web source document into a Pascal program that may be com-
piled in the usual way with the on-line Pascal compiler (e.g., pc(1)). The output file is
all in lower case and packed into lines of 72 characters or less, with the only concession
to readability being the termination of lines at semicolons when this can be done conve-
The Web language allows you to prepare a single document containing all the information
that is needed both to produce a compilable Pascal program and to produce a well-formatted
document describing the program in as much detail as the writer may desire. The user of
Web must be familiar with both TeX and Pascal. Web also provides a relatively simple,
although adequate, macro facility that permits a Pascal program to be written in small
The command line should have either one or two names on it. The first is taken as the Web
file (and .web is added if there is no extension). If there is another name, it is a
change file (and .ch is added if there is no extension). The change file overrides parts
of the Web file, as described in the Web system documentation.
The output files are a Pascal file and a string pool file, whose names are formed by
adding .p and .pool respectively to the root of the Web file name.
pc(1), pxp(1) (for formatting tangle output when debugging), tex(1).
Donald E. Knuth, The Web System of Structured Documentation.
Donald E. Knuth, Literate Programming, Computer Journal 27, 97-111, 1984.
Wayne Sewell, Weaving a Program, Van Nostrand Reinhold, 1989, ISBN 0-442-31946-0.
Donald E. Knuth, TeX: The Program (Volume B of Computers and Typesetting), Addison-Wesley,
1986, ISBN 0-201-13437-3.
Donald E. Knuth, Metafont: The Program (Volume D of Computers and Typesetting), Addison-
Wesley, 1986, ISBN 0-201-13438-1.
These last two are by far the largest extant examples of Web programs.
There is an active Internet electronic mail discussion list on the subject of literate
programming; send a subscription request to email@example.com to join.
Web was designed by Donald E. Knuth, based on an earlier system called DOC (implemented by
Ignacio Zabala). The tangle and weave programs are themselves written in Web. The system
was originally ported to Unix at Stanford by Howard Trickey, and at Cornell by Pavel Cur-
Web2C 7.3.1 12 February 1993 TANGLE(1)