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Introduction to Scala

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Hello, World!

2:22 with andi mitre

In this video we will use the scala REPL for an up and running example of Scala.

There are two ways of creating variables in Scala. 0:00
The preferred way is by creating a constant using the key word val. 0:03
This way of creating a variable supports the second idea of functional programming, 0:07
as the contents of a val cannot be changed. 0:12
Additionally, you can create a mutable variable in Scala 0:15
by using the key word var whose contents can be changed. 0:19
Let's see how this works in the REPL, the interactive shell, which we can get to by 0:23
opening up a terminal in a Mac or command prompt in Windows and typing Scala. 0:27
Let's open up the terminal to start the Scala REPL. 0:33
REPL stands for read, evaluate, print, and loop, and 0:37
it's very useful in evaluating expressions. 0:41
Here, we've created a variable name greeting. 0:53
A constant whose values cannot be changed. 0:55
Attempting to reassign the value of variable greeting 0:58
will throw a reassignment to val error. 1:02
Let's take a look at that. 1:05
Let's take a similar approach, but with a mutable variable this time. 1:10
We've created a variable called message, which contains the string, hello world. 1:19
Because vars are mutable, we can reassign its value. 1:24
In both instances, you may have noticed two things. 1:33
First, we aren't required to provide a semicolon at the end of the statement, and 1:37
that's because Scala supports semicolon inference. 1:41
Second, we didn't have to specify the parameter type. 1:45
That's because scala has a built in type inference mechanism 1:49
which allows it to figure out what the type of variable should be. 1:53
Although not recommended, we can always supply the semicolon or 1:57
the type information if we really wanted to. 2:01
Let's take a look. 2:04
Awesome, we learn how to create values and variables in Scala. 2:12
In the next video, we will create our first Scala app and learn about functions. 2:16
See you there! 2:21