Part 12 and the keystone of the Functional Programming in Practice series. Throughout the series I kept saying "we will verify this with property tests later." This is later, and it turns out the technique is the direct ancestor of the AI evals the whole industry is reinventing

Part 11 of the Functional Programming in Practice series. This is the part that answers the question you have been holding since Part 1: if functions cannot have side effects, how do you build anything that actually does something? Hey there, Coding Chefs! 👨‍💻 We need to settle a debt. Way

Part 10 of the Functional Programming in Practice series. Part 9 left us with a wall: we have a map for Option, for Either, for Array, but no way to write one map for all of them. This part is the honest story of why, and what to do about

Part 9 of the Functional Programming in Practice series. Part 7 gave us category theory, Part 8 used it for Monoids. This part uses it for the most famous functional tool of all, and reveals what .map() was secretly doing the whole time. Hey there, Coding Chefs! 👨‍💻 You have called

Part 8 of the Functional Programming in Practice series. Part 7 gave us the category-theory map: objects, arrows, and lawful composition. This part cashes it in on the most ordinary thing in programming, combining two things into one. Hey there, Coding Chefs! 👨‍💻 Count how many times you have written code

Part 7 of the Functional Programming in Practice series. This is the hinge of the whole series. Everything before it was concrete tools. This part is the one simple idea those tools secretly stand on, and the map for everything still to come. Hey there, Coding Chefs! 👨‍💻 Functor. Monoid. Monad.

Part 6 of the Functional Programming in Practice series. Parts 4 and 5 used Option and Either, which were both built from the same shape: a type that is "this OR that," with a tag to tell them apart. This part names that shape and shows what it