Titlecase.el

Adapted from Hung-Yi and novoid, and with rules from Capitalize My Title

It turns out, capitalizing titles is Hard. This library only does it in English, and even then, it’s pretty jankily put-together. It’s due, mostly, to the fact that many words can mean many different things, depending, and I don’t want to put a whole dictionary in this package just to make capitalizing headings a little easier. I’ll expound more on this in the USE section, below.

Installation

Make sure both titlecase.el and titlecase-data.el are in your load-path, and require as per usual. If you use a package manager like package.el or straight.el, that should be done for you.

Note that you will need a package manager that can pull from arbitrary git repositories at the moment (like straight.el), since this package is not currently in any elpa-style repositories.

The only setting you really should need to set is titlecase-style, which see. Each of these styles has a different set of rules regarding which words to capitalize in a title. After you’ve set titlecase-style, you can bind the command titlecase-dwim to a key, or call it using M-x, and it will either title-case your region (if it’s active) or the current line.

The tricky part is figuring out what words to capitalize in the title.

Articles (a, an, the) are downcased.

The first word of a title and all “important words” (generally nouns, pronouns, adjectives, verbs, and adverbs) are capitalized. The last word of a title is always capitalized, but only in Chicago, AP, Bluebook, AMA, NY Times, and Wikipedia.

All/ prepositions are downcased in Chicago, MLA, AP, NY Times, and Wikipedia, regardless of length; for APA, Bluebook, AMA, and Wikipedia, only prepositions shorter than 5 letters are (presumably, capitalize those longer than 5 letters, however only Wikipedia was clear on that point).

Coordinating conjunctions are capitalized in Chicago and APA (presumably), but downcased in MLA, AP, Bluebook, AMA, NY Times, and Wikipedia.

Hyphenated words are tricky: I could possibly figure out a way to have lookup tables to determine when to capitalize the second part of a hyphenated word, but I haven’t implemented them yet. At any rate, the rules tend to be vague enough that it’s hard to program anyway: For example, Chicago, APA, MLA, and AP lowercase the second word “after a hyphenated prefix (e.g., Mid-, Anti-, Super, etc.) in compound modifiers,” but MLA and APA capitalize the second part of “hyphenated major words (e.g., Self-Report not Self-report).

Perhaps unsurprisingly, the AMA (American Medical Association, used in the scientific community) has the most comprehensive capitalization rules around hyphenated words. I’ll just copy-paste the bullet points here:

• Lowercase the second word in a hyphenated compound when it is a prefix or suffix (e.g., “Anti-itch”,”world-wide”) or part of a single word.
• Capitalize the second word in a hyphenated compound if both words are equal and not suffices or prefixes (e.g., “Cost-Benefit”)
• Capitalize the first non-Greek letter after a lowercase Greek letter (e.g., “ω-Bromohexanoic”)
• Lowercase the first non-Greek letter after a capital Greek letter (e.g., “Δ-9-tetrahydrocannabinol”)

(The AMA also has a rule about capitilizing the genus but not species epithet, but the lookup on that would be wild as hell, so I trust yall to know on that one.)

To as an infinitive is downcased in all except AP. This is a rule I simply cannot implement without knowing whether the next word is a verb, which would require expensive lookups, which even then wouldn’t be foolproof.

Now that I’m thinking about it, most styles count phrasal verbs (like “play with”) as important enough to capitalize, when “with” would usually not be capitalized, but again, open categories like phrasal verbs simply do not work in a package like this.

ALL OF THIS IS TO SAY that titlecase offers a best-effort attempt to titlecase a line or region of text, but you should absolutely double-triple-check against the style guide you’re writing for if you’re trying for publication or something like that.

Further Customization

While titlecase-style should be the only customization option you need to tweak, it wouldn’t be Emacs if there weren’t many more.

Most of these style guides fail to specify what to do when a word does not fit one of the criteria listed. The customization option titlecase-default-case-function controls what to do there.

None of the styles specify what to do after certain punctuation marks like . : ? etc. Some do specify “capitalize the first word of … any subtitle/subheading,” which might refer to a word after :, but I’m not sure. Anyway, you can customize titlecase-force-cap-after-punc to a regexp which, if it matches after a word, will force the next word to be capitalized.

For even more customization, of course, you can tweak titlecase.el’s defvar values, but There Be Monsters.

Finally, there’s the titlecase-style sentence if you want some long-asked-for sanity in your titles.

License

This package is licensed under the terms of the GNU General Public License, version 3. See LICENSE for the full text.

Contributing!

Please contribute! This is a herculean effort, so feel free to open issues, pull requests, whatever. I’m excited to hear from you!