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# Scala Functions

## Examples

#### Anonymous Functions

Anonymous functions are functions that are defined but not assigned a name.

The following is an anonymous function that takes in two integers and returns the sum.

``(x: Int, y: Int) => x + y``

The resultant expression can be assigned to a val:

``val sum = (x: Int, y: Int) => x + y``

Anonymous functions are primarily used as arguments to other functions. For instance, the map function on a collection expects another function as its argument:

``````// Returns Seq("FOO", "BAR", "QUX")
Seq("Foo", "Bar", "Qux").map((x: String) => x.toUpperCase)``````

The types of the arguments of the anonymous function can be omitted: the types are inferred automatically:

``Seq("Foo", "Bar", "Qux").map((x) => x.toUpperCase)``

If there is just one argument, the parentheses around that argument can be omitted:

``````Seq("Foo", "Bar", "Qux").map(x => x.toUpperCase)
``````

## Underscores shorthand

There is an even shorter syntax that doesn't require names for the arguments. The above snippet can be written:

``Seq("Foo", "Bar", "Qux").map(_.toUpperCase)``

_ represents the anonymous function arguments positionally. With an anonymous function that has multiple parameters, each occurrence of _ will refer to a different argument. For instance, the two following expressions are equivalent:

``````// Returns "FooBarQux" in both cases
Seq("Foo", "Bar", "Qux").reduce((s1, s2) => s1 + s2)
Seq("Foo", "Bar", "Qux").reduce(_ + _)``````

When using this shorthand, any argument represented by the positional _ can only be referenced a single time and in the same order.

## Conclusion

In this page (written and validated by ) you learned about Scala Functions . What's Next? If you are interested in completing Scala tutorial, your next topic will be learning about: Scala Futures.

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