St. Laurent - Introducing Erlang: getting started in functional programming

by Simon St.Laurent

Copyright 2017 Simon St.Laurent. All rights reserved.

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978-1-491-97337-0

[LSI]

Erlang has long been a mysterious dark corner of the programming universe, visited mostly by developers who need extreme reliability or scalability and people who want to stretch their brains.

Developed at Ericsson to serve on telephone-switching equipment, it seemed like a strangely special-purpose language until recently, when our computer and network architectures came to look a lot more like massively parallel telephone-switching equipment. Thanks to the spread of NoSQL data stores CouchDB and Riak, you may already be using Erlang without realizing it, and Erlang is moving out into many more fields. WhatsApp is a classic Erlang success story.

Erlang provides a short path from discipline to resilience. The decisions made by the creators of the language let the Erlang environment seamlessly scale and handle failure in ways that other environments have to manage by adding ever more infrastructure. In my utterly biased opinion, any application that needs to run for a long time and scale to many interactions should be built in Erlang (or its more recent cousin Elixir).

If you come from pretty much any background other than functional programming, exploring Erlang will require you to clear your mind of many of the techniques used in other programming languages. Forget classes, forget variables that change valueseven forget the conventions of variable assignment.

Instead, youre going to have to think about pattern matching, message passing, and establishing pathways for data rather than telling it where to go. Erlang programming can feel like making a key whose teeth set the tumblers on a lock just right for the key to pass, or playing pachinko and watching the balls fall through a maze.

Sound strange? It isbut also enjoyable, powerful, and fun.

My first explorations of Erlang confused me and excited me at the same time. Id had some experience with what Id called invariant variables, variables that can be bound to a value only once, in XSLT. That created a lot of headaches for me until I realized I was coming at the problems all wrong, and then it suddenly made sense.