The Missing Map for Learning FP
Groxio is now in our second year of teaching programmers to code functionally, and have fun doing it. Along the way, I’ve led more than a dozen groups of new and intermediate programmers through the treacherous waters of LiveView and OTP. In this post, I want to share with you a breakthrough I’ve found in these classrooms, a pattern called CRC, or construct-reduce-convert. Better yet, think construct |> reduce |> convert. It’s a simple story. Like all stories, this one has a beginning, a middle and an end.
You have doubtlessly noticed that Elixir, Groxio, the Jolly Roger, and treasure maps all share a big bright X. Sadly for you, dear reader, that means you’re going to have to wade through ten whole minutes of silly pirate wordplay. So, edge out onto this plank with me and we’ll stagger along these skinny, shivering timbers together.
A Treasure Map on a Number Line
It might surprise you that pirates love computers. After all, piracy is all about doing things the easy way. Let someone else suffer through mining and assembling all of that treasure, and slip in to reap the benefits at the end.
Computers, too, are about using machines to do the hard work so we can reap the benefits. So, let’s talk about one of the things pirates and programmers have in common. Maps. Treas-arr maps.
There’s a map in my possession that describes the exact location for the lost treasure of that great Elixir pirate, Purple Beard. Loosely translated, the map is a big fat conglomeration of buccaneer speak and pirate code that boils down to the basic translation:
Two steps forward, and one step back.
You might question my sanity, but I know it’s a map, and I am going to prove it. All I need is the map code with a beginning, a middle, and an end that will leave me swimming in treas-arr.
A H-arr-owing Tale
If you know that Purple Beard’s favorite movie is The Hitchhiker’s Guide to the Galaxy, you already know where to st-arrr-t. Open up an IEx prompt and follow along:
iex(1)> starting = 42
