These posts seek to describe a process by which a Scala dev can reasonably (responsibly) introduce Functional Programming (FP) in Scala into an Object Oriented (OO) Java development atmosphere. It can also serve as an entry point for an OO dev into the Scala community. They are based on a talk I gave at the Typelevel Summit in Philadelphia in 2016. Here are the slides and index cards from that talk. A video is available on YouTube.
We'll transform from OO paradigms to FP paradigms through five key ideas:
- Immutability as Default
- Combinators over loops, null & throw
- Case Classes for auto-encapsulation
- Objects are not Coroutines
- Type Classes over Subclasses
And provide practical examples using 3 libraries:
Each of these ideas builds upon the last and by the end we'll have a solid foundation for introducing FP and Category Theory without even saying any of the "M-words".
Before starting it is important to note that many of the people who develop software do not have Computer Science (CS) degrees. They will sometimes have a degree in another science or engineering discipline. Often, they will have no degree at all. An extension of this idea is you don't need a degree to define flatMap.
This fact is important to us because, the vernacular of CS is different from the vernacular of other disciplines. On the other hand, we are assuming an audience of OO developers so, some CS terminology is ok and indeed will be present throughout. Wherever OO words fail us, we will find "plain old English" ways of describing idioms and ideas. We will be coaching usage, strategies and tactics not terms and vocabulary.