tangle - translate WEB to Pascal


tangle webfile[.web? [ ''changefile[[.ch?'' ]


This manual page is not meant to be exhaustive. The complete documentation for this version of TEX can be found in the info file or manual Web2C: A TeX implementation.

The tangle program converts a W EB source document into a Pascal program that may be compiled 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 conveniently.

The W EB 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 W EB must be familiar with both TEX and Pascal. W EB also provides a relatively simple, although adequate, macro facility that permits a Pascal program to be written in small easily-understood modules.

The command line should have either one or two names on it. The first is taken as the W EB 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 W EB file, as described in the W EB 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 W EB file name.


pc(1)?, pxp(1)? (for formatting tangle output when debugging), tex(1).

Donald E. Knuth, The W EB 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, M ETAFONT : 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 W EB programs.

There is an active Internet electronic mail discussion list on the subject of literate programming; send a subscription request to to join.


W EB 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 W EB . The system was originally ported to Unix at Stanford by Howard Trickey, and at Cornell by Pavel Curtis.

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