The classic Dyalog APL reference, Mastering Dyalog APL, has outlived its 2009 edition. Written by Bernard Legrand, the book served as the de facto standard for learning the language, but Dyalog APL has evolved considerably. A rework by Rodrigo Girão Serrão converts the text into Jupyter Notebooks for a more interactive learning experience.

The new version targets Dyalog APL 12.0, adding sections and chapters that didn't exist in 2009. Prose and examples draw from the original where possible, with updates and rewrites where needed. A static online version exists now, and a printed edition is planned for those who prefer paper.

The project lives on GitHub, where contributors shaped the rework. Adám Brudzewsky receives particular mention. This update matters because APL developers need current documentation that matches the language they're actually using.