Functional Scala: Quiz with Lists – common list functions, handcraftet

Welcome to another episode of Functional Scala!

As promised within the last episode, we’re going to take another detailed look at some more commonly used list functions. As we wanna become well acquainted with the functional side of Scala, we’re again going to implement those list functions one by one. Along the way, we’ll get a better and better understanding on how to apply some of the typical tools within the world of functional programming, like pattern matching, recursion or function composition.

As it turned out, most of us learn best in a synthetical way (that is not by dissecting the frog, but to build one). For that, we’re gonna change the style of the following sections. For every useful function, we’re first looking at their intended behaviour, maybe along with some exemplary showcases. Only when we grasp the intention, we’re trying to come up with a sensible idea for their realization and finally with an implementation. You might consider the whole episode like a little quiz and try to come up with your own solutions before you’ll take a closer look at the presented ones.

Functional Scala: Essential list functions

In the last two episodes we came up with the basic idea of persistent (read immutable) list-like data structures and how to construct and deconstruct (read pattern match) them using a sugarized notational form. We also talked big about their non-destructive nature when it comes to e.g. updating a given list or removing some elements. In this episode, we’ll finally inspect some of those commonly used list functions. While we’re going to reimplement the most essential ones,  you’ll hopefully get a better feeling for the  basic principles and characteristics which build the foundation for operating on persistent data structures in a non-destructive way (preserving the structure of given list values).

Functional Scala: List sugarization

In the last episode we started to look at persistent list-like data structures. We came up with an algebraic datatype which allows to construct arbitrary lists, featuring parametric polymorphism with regard to the type of the lists content. So far, we didn’t see the non-destructive nature of those datatypes when it comes to updating a given list or removing some elements.

Bear with me. We’re going to inspect a bulk of widely accepted, commonly used list functions, operating on persistent data structures in a non-destructive way! But before, we’ll need to prepare ourself with a set of tools for an easier way of tinkering with our list-like data structure.