Anil Dash quote-tweeted this post from Ian Brown on Mastodon this morning:

I was so excited to learn that abbreviations like “a11y” or “c14n” are called “numeronyms” that I wrote an #Emacs^H^H^H^H^H^H #E3s extension to make it easier to use them.

The tweet1 links to this GitHub page. First I thought it was funny to see a link to an Emacs Lisp script the day after I posted about my date-convert script. Then I thought “I want to be able to do that, but not in Emacs.” So I built this Keyboard Maestro macro, which I also called Numeronymize:

Screenshot of Keyboard Maestro Numeronymize macro

If you download and install it, it will appear in your Global Macro Group.

Here’s how to use it: Type the word you want to numeronymize in any editable text field. For example,


With the cursor blinking at the end of the word, type ⌃⌥⌘3 (on standard American keyboards, the number symbol, #, is on the 3 key). The word before the cursor will be selected and shortened to its numeronym,


Honestly, I don’t think I’ll be using this macro very much, but it was fun and easy to write. The key is the Perl one-liner in the third step:

/usr/bin/perl -C -pe 's/(.)(.+)(.)/$1 . length($2) . $3/e'

I have more than one Perl executable on my computer, so I’m being explicit here about calling the one in /usr/bin that comes with macOS. The -C switch tells Perl to treat the input and output as UTF-8 (more on this below); the -p switch tells it to loop through the input, apply the code to it, and print out the result; and the -e switch tells it to treat the following string as the code to execute:

s/(.)(.+)(.)/$1 . length($2) . $3/e

This is the cool part, because Perl’s substitute command has an e option that means “evaluate.” It treats the replacement as a chunk of Perl code, evaluates it, and returns the result. Here, it concatenates the first letter, the length of the middle string of characters, and the final letter. When I saw what Brown’s numeronymize extension did, I immediately thought of this feature of Perl and knew I could do it in a one-liner.

The -C switch isn’t needed if all we care about are words made of ASCII characters. But what if we want to shorten this?


Without the -C, we’d get


because the length function normally returns the length in bytes, and the ä takes up two bytes. But with the -C, length understands that we want characters, not bytes, so the macro returns


which is what we want.

A couple of other notes:

Thanks to Ian Brown for making the Emacs extension and to Anil Dash for bringing it to wide attention. Dash says his favorite numeronym is “e13n,” but I think he’s leaving out one of the T’s.

  1. Yes, I’m using “tweet” and “retweet” to refer to posts on Mastodon. Since Twitter has given up its name, I feel these words are now fair game for any Twitter-like service. After all, they were invented by the Twitter users, not the company.