Agent skill · writing content · github
em-dash
Expert on the history, origin, and correct use of the em dash. Use when writing or reviewing code, comments, or data files to avoid em and en dashes, defaulting to never using them and replacing any found with a hyphen (-). Includes strong knowledge of punctuation marks and the proper usage of punctuation characters when writing comments.
Why this skill is useful
Codifies the standard usage of em dashes in code comments and data files, preventing the AI from guessing punctuation conventions.
What it needs
About 6k tokens when loaded. Last updated 2026-08-07. 37,534 stars on the source repository.
What this skill does
em dash The em dash (U+2014, \u2014; not the hyphen-minus -) is the longest of the standard dashes, and is the Swiss Army knife of punctuation. Its history is a fascinating journey from handwritten manuscripts to mechanical constraints, literary rebellion, and modern digital dominance. Here is a breakdown of how the em dash evolved: History of the em dash Early Beginnings (15th-18th Century) The First Dashes: Early appearances of the dash in English literature date back to 1580 in private letters and 1588 in English drama. They were often used to indicate pauses, self-interruption, or an unfinished thought Gutenberg and Early Printing: The em dash officially emerged as a standardized typesetting mark during the 15th-century printing revolution The Etymology The "M" Width: The em dash is named because its standard length is equal to the width of the capital letter "M" in the specific typeface being used (Similarly, the slightly shorter en dash is the width of the letter "N") Literary Popularity (17th-19th Century) The Author's Tool: By the 17th and 18th centuries, it became a beloved tool for writers mimicking the natural lurches, stutters, and rhythms of speech Dickinson Dashes: In the 19th century, poets like Emily Dickinson famously used the em dash for emotional weight, rhythm, and to invite reader interpretation. This became so synonymous with her work that they are often informally called "Dickinson Dashes" The Typewriter Era (19th-20th Century) The Double-Hyphen Compromise: When typewriters were introduced, they lacked a dedicated key for the em dash. …
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills github/em-dash