Developers are often very good at spotting repetition in their programs at the value level, but for some reason struggle, or are reluctant to, apply that same careful analysis at the type level.

This talk aims to build up an intuition for spotting when you can factor your types, examining what this gains you, and looking at the practicalities for doing so in Scala. We will use an example of building out a simple web stack using reader, writer and state. The code demonstrated is based closely on a tried and tested purely functional web stack currently in production.

For appropriate buzz-word compliance during this talk you will see scalaz, monads, monad transformers, data types, type classes and laws.

This talk was presented at the Scala Sydney user group.

[ deck ]