Scala, a modern Functional and OOP language

• Andrew Dale
• andrew.dale@uoit.net

Brief synopsis of the language

Scala Basics

• Scala is a general-purpose programming language which also supports functional programming --> The language is multi-paradigm
• The language was designed to address criticisms of Java -- the language on which it is built.
• The language first appeared in January of 2004, almost # 15 years ago.
• Developed at the Programming Methods Laboratory of École Polytechnique Fédérale de Lausanne
• The language's typing discipline is static, strong, inferred and structual.
• Utilizes .scala and .sc filetypes
• Lexical Scoping

Syntactic Excellence

Specifically, Scala does not have a "let" form Similar to Java, Scala must have a main definition to run

Eg

main(args: Array[String]) {
	println("Hello World")
}

A simple 'foreach' loop:

for(i <- List.range(0, 10, 1)){
	if(i % 2 == 0){
		println("Even")
	}else{
		println("Odd")
	}
}

Tools of the Trade

Scala can be developed in a multitude of ways, most commonly in IntelliJ IDEA

Or similarly can be developed on the command line via text-editors such as VIM

Either way, the project manager SBT is used to manage larger scala projects Utilizing from the command line, SBT is rather (read: isn't) straight-forward. scala> (can also be {projectname}> which allows one to input certain commands, such as ~run/run which will build the project along and compile it. One can also pull a sbt template utilizing the command:

_scala> sbt new scala/{templatename}.g8_ // for my project I utilized;
_scala> sbt new scala/scala-seed.g8_ // which creates the directories, build file (build.sbt) etc.

Unfortunately however, it would seem that SBT (at least in my limited personal experience) is oft convoluted and doesn't feel great to use -- read: often feels clunky. Especially in comparison to Leiningen.

The Standard Library

Given that Scala is built upon the JVM, almost all functionality is cross-compatible with Scala (as in Java -> Scala) This includes standard .Math etc etc.

For Example from Scalas documents (@ https://www.scala-lang.org/api/current/) Mathematical Constants:

val E: Double(2.718281828459045)
val Pi: Double(3.141592653589793)

Scalas standard library is pretty -- and intuitive. We can utilize the standard math lib to find min and max of {type}

E.g.

def max(x: {type}, y: {type}): {type}
def min(x: {type}, y: {type}): {type}

// Ceiling and Floor Functionality
def ceil(x: Double): Double
def floor(x: Double): Double

Amongst others, including, exp, log, round, trig functions etc.

Even more interesting, at least in my opinion, Scalas math lib also includes a conversion between radians and degrees. The standard library (as it is shared with Java) also contains sorting implementations for {type} E.g. quicksort, stablesort

def quickSort(a: Array[Int]): Unit

About open source library

Scala has a multitude of open-source libraries available, the two in particular that I found interesting were Breeze and Vegas (two data visualization libraries) to help bridge the gap for burgeoning data scientists with an interest in Scala. Vegas is touted as the Matplotlib for Scala and whilst this may have been true, a lack of updates and contributions have let the project fall to the way-side lacking support for the newest updates of Scala itself. #Breeze Example Upon importing the required dependencies, we can plot data (and also subsequently save it).

import breeze.plot._
// For my own project I used the standard scala io
// Once we have our data into some sort of container, array/list etc
// We can now plot x vs y
// For this example we'll forego typical Scala practice
val f = Figure()
val Plot = f.subplot(0)

Plot.title = "Yahoo Financial Data"
Plot.xlabel = "Days"
Plot.ylabel = "$ Value"
Plot += plot(days, highInt)
Plot += plot(days, lowInt)

f.refresh()

Analysis of the language

I'll be honest, I'm not particularly a fan of the language after a brief period of use, albeit that could certainly change over time