The Developer’s Guide to Scala Implicit Values (Part II)

Imagine a rectangular grid of cells, in which each cell has a value – Either black (dead) or white (alive). And imagine that:

  1. Any live cell with two or three live neighbors survives for the next generation.
  2. Any cell with four or more neighbors dies from overpopulation.
  3. Any cell with one or no neighbors dies from isolation.
  4. Any dead cell with exactly three neighbors comes to life.

 

These are the four simple rules of Conway’s Game of Life . You could hardly imagine a simpler set of rules to code on your computer and you wouldn’t expect any interesting result at all, but…

Behold the wonders of its hidden might!

The Developer’s Guide to Scala Implicit Values (Part I)

Implicit parameters and conversions are powerful tools in Scala increasingly used to develop concise, versatile tools such as DSLs, APIs, libraries…

When used correctly, they reduce the verbosity of Scala programs thus providing easy to read code. But their most important feature is that they offer a way to make your libraries functionality extendible without having to change their code nor needing to distribute it.

A great power comes with a great responsibility however. For new comers, as well as for relatively experienced Scala users, they can become a galaxy of confusions and pitfalls derived from the fact that the use of implicit values imply the compiler making decisions not obviously described in the code and following a set of rules with some unexpected results.

This post pretends to shed some light on the use of implicit values. Its content isn’t 100% original, it is just a tourist guide through this full of marvels, and sometimes dangerous, code jungle.
As most of those monstrous things that make us shiver, implicit values are mostly harmless once you get to know them.

Variance in Scala (“Luke, he is your father too”)

When working with Big Data, sometimes it’s useful to remember that powerful products wouldn’t work properly without the tools that build them. It’s possible to start programming in Scala with a few case classes and a bunch of for-comprehensions, but those are only little scratches in a huge ice surface like Scala is. It may not be enough to make your code clean and comprehensible.  I’ve been developing with this programming language for almost 4 years, and every day I discover a new feature that surprises me. That acknowledgement, in the end, is the main reason to keep digging deeper into Scala.