#Scala for loop generator
#Scala for loop code

Let’s say that we only want to print the names of the women in the collection. While the functionality of the for loop pretty much ends with the above example in Java or C# Scala’s version of the for loop has a lot more to offer.

#Scala for loop generator

The <- operator is called a generator and a for expressions must always start with a generator which specifies which collection of objects to iterate over and a temporary variable that holds the current object.Ĭompared to the C# equivalent there is more differences, most notably that we in C# use the foreach keyword to traverse a sequence of objects instead of the for keyword. The same loop in Java would have looked like this: for(Person person : people)Īnd in C# it would have looked like this: foreach (var person in people)Īs we can see the for loop is very similar to Java’s, except it doesn’t require us to specify the type of the temporary variable as the compiler can infer it and the : operator is replaced with the <- operator which can be thought of as directing instance from the sequence being iterated over to the temporary variable.

#Scala for loop code

for(person <- people)Īs you might guess the code above will print the name of each Person object in the list.

We can traverse the list, “comprehending” each instance using a for loop that syntactically is very similar to Java’s. To have something to work with in our examples, let’s begin by creating a simple Person class and a list of Person instances: class Person(val name: String, val female: Boolean) The for loop in Scala is referred to as “for comprehension” or “for expression” in the Scala community and it can do some pretty funky stuff. Result = if(a = b) 'It's true' else 'Not really' For comprehensions This means that we can re-write if statements such as this: if(a = b) In Scala however if statements are expressions meaning that they return a (single) value. In Java, C# and many other programming languages conditional branches are statements that can control execution of code but don’t produce any resulting value themselves. As we’ll see they to have some interesting characteristics compared to languages such as Java or C#.

In this part we’ll look at how standard programming constructs such as if statements and different types of loops work in Scala. In the previous part of the Learning Scala series we looked at defining and invoking methods in Scala which has some interesting characteristics.