May 24, 2026
Brackets, symbols, and backlash
Mastering Dyalog APL
The cult favorite coding book goes interactive, and the comments are split between hype and “but why”
TLDR: A classic 2009 book for learning the niche language Dyalog APL is being remade as an interactive online guide, with a print version also on the way. Commenters loved the hands-on format but kept asking the messier question: is this fascinating skill actually useful, or just fun to admire from a distance?
A beloved old-school guide to Dyalog APL—a famously symbol-heavy programming language that looks almost alien to outsiders—is getting a big makeover. The 2009 book is being rebuilt as an interactive online edition in Jupyter Notebooks, with a static web version now and a fresh printed edition promised later. On paper, this is a practical update: the language has changed, the original book is aging, and readers can now suggest fixes on GitHub like it’s a living document instead of a dusty relic.
But the real show is in the comments, where the crowd instantly turned this quiet book update into a mini identity crisis. One camp is genuinely thrilled, saying interactive examples are exactly what a strange, symbol-packed language needs because learning it is all about repetition and “muscle memory.” Another camp is giving strong “looks cool, will never use” energy, with one commenter basically filing it under “bookmark for a rainy day.” And then came the killer line: “I really wish learning this had a positive RoI”—a brutally honest jab that sums up the biggest tension here. People seem to admire APL the way you admire a beautiful, impractical sports car: stunning, fascinating, maybe not how you’re getting to work.
There was also classic internet practicality: one user swooped in with a PDF link for fellow paper-lovers, while another asked whether learning APL could help with more mainstream tools like Matlab. So yes, the update is real—but the comment section’s verdict is even juicier: deep respect, mild confusion, and a lot of side-eye about whether this knowledge will ever pay off.
Key Points
- •The article presents *Mastering Dyalog APL* as a widely used book for learning Dyalog APL and says the online version is currently a work in progress.
- •The new version is being built from Jupyter Notebooks in a GitHub repository to provide a more interactive learning experience.
- •A static online version already exists, and a printed edition is planned for readers who prefer paper books.
- •The first edition was published in November 2009 and written by Bernard Legrand, with several acknowledged contributors.
- •The current rework is by Rodrigo Girão Serrão and includes updated explanations, revised examples, and new material covering features added since Dyalog APL 12.0.