TANGLE(1)

👑 TANGLE — section 1 of the general commands manual 👑

okay so, bestie, lemme put you on 💖 this is the manual page for tangle, a literal icon of the literate-programming world. It lives in the General Commands Manual, it's section 1, and it's about to change your whole workflow, fr fr.

---

✨ NAME ✨

tangle — translate WEB to Pascal 🦋

---

🌸 SYNOPSIS 🌸

tangle [options] webfile[.web] [{changefile[.ch]|-} [outfile[.p]]]

---

💅 DESCRIPTION 💅

ngl, this manual page is not meant to be exhaustive. The complete documentation for this version of TeX lives in the info file or the manual Web2C: A TeX implementation. Go read that if you want the whole lore, iykyk.

The tangle program converts a Web source document into a Pascal program, and then you compile it the usual way with the on-line Pascal compiler (like pc(1), hey bestie 👋). The output file gets packed into lines of 72 characters or less, and the only concession to readability is that lines get terminated at semicolons when this can be done conveniently. That's it. That's the aesthetic. 💀

The Web language lets you prepare a single document containing all the information 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 way that is so main character energy. ✨

But heads up — the user of Web must be familiar with both TeX and Pascal. No skipping prerequisites, bestie, that's the vibe check. Web also provides a relatively simple, although adequate, macro facility that permits a Pascal program to be written in small easily-understood modules. Modular queen. 👑

So the command line should have one, two or three names on it:

• The first is taken as the Web file (and .web is added if there is no extension).
• If there's a second name, it's 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.
• If there's a third name, it's the Pascal output file (and .p is added if there is no extension). In this case you can specify an empty change file with - as the second argument. Otherwise, the name of the Pascal file is formed by adding .p to the root of the Web file name.

An optional second output file is a string pool file, whose name is formed by adding .pool to the root of the Pascal file name. Cute, right? 🎀

---

🔥 OPTIONS 🔥

This version of tangle understands the following options. Note that some of these options may render the output unsuitable for processing by a Pascal compiler — like, read that twice, bestie, it's not a drill 🚨

• --help — Print help message and exit. Slay.
• --length number — Compare only the first number characters of identifiers when checking for collisions. The default is 32; the original tangle used 7. Glow-up fr.
• --loose — When checking for collisions between identifiers, honor the settings of the --lowercase, --mixedcase, --uppercase, and --underline options. This is the default.
• --lowercase — Convert all identifiers to lowercase.
• --mixedcase — Retain the case of identifiers. This is the default.
• --strict — When checking for collisions between identifiers, strip underlines and convert all identifiers to uppercase first. Strict mode is giving discipline 💅
• --underline — Retain underlines (also known as underscores) in identifiers.
• --uppercase — Convert all identifiers to uppercase. This is the behaviour of the original tangle.
• --version — Print version information and exit.

---

🌈 ENVIRONMENT 🌈

The environment variable WEBINPUTS is used to search for the input files, or the system default if WEBINPUTS is not set. See tex(1) for the details of the searching. Go off, environment variable 🫶

---

🦋 SEE ALSO 🦋

• pc(1)
• pxp(1) (for formatting tangle output when debugging)
• tex(1)

Also, the required reading, no cap 📚:

• 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.

Those last two are by far the largest extant examples of Web programs. Literally massive. 😭

There is an active Internet electronic mail discussion list on the subject of literate programming; send a subscription request to litprog-request@shsu.edu to join. Join the group chat bestie, it's giving community 🌸

---

💜 AUTHORS 💜

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 Curtis. Legends only. 👑

---

and that's the whole page, bestie 💖 go forth and tangle, you're gonna eat

This page is brought to you by Web2C 2025, dated 02 March 2022 — version info and date, delivered with love, mwah 🎀✨