ruby
Naive Bayes classification in plain Ruby: how prior and posterior probabilities decide the winning class, then a working spam filter that classifies email titles. Also where the algorithm shines: sentiment analysis, recommendations, and fraud detection.
cookies
Rails CookieOverflow strikes when a cookie exceeds 4096 bytes. How to inspect cookies in Chrome dev tools, read the session dump on the error page, and use the cookie_debugger gem to log exactly which session key is eating the space, even in production.
ruby
ActiveRecord callbacks bring tight coupling, slower transactions, and painful debugging. Why before_save and after_save hooks in Rails models cause trouble, and how replacing them with an explicit process class makes the same flow readable and easy to debug.
Apipie looks like an easy way to document a Rails API, but check its limits first: no advanced type constraints like exactly_one_of, only partial OpenAPI support, and weak handling of output examples. What to weigh before picking the gem for a larger application.