CppCon 2023

Monads get all the press. Functors are often presented as a prerequisite to monads. Applicative (functor) almost never gets mentioned. But it's massively useful - to the point where a lot of the time when we think about a "monadic interface" what we really want is an applicative interface.

This talk will put applicative in the limelight, showing how it works and why it's so powerful, with lots of examples grounded in code; there are no category theory diagrams in this talk. Attendees will come away with a solid understanding of the applicative pattern and its many uses. And as a byproduct, their opinions of monads will probably change too.

Optionals. Expected. Ranges. Futures. Parsing. Validation. Error Handling. Transforms. Functions themselves. These are all examples where thinking in terms of applicatives (and importantly, NOT just reaching for "a monadic interface") helps us write simpler, more composable code.

If you're kind of fuzzy about functors and monads, what's missing is probably the third piece of the puzzle: applicative.