Give another name to a type

An alias gives a more expressive local name to an existing type. It improves the vocabulary of the code without creating a new type.

Declare an alias

Place the existing name after use, then the local name after as:

use int as Count

func main() {
    let total:Count = 3
    print(total)
}

The program prints:

3

Here, Count and int designate exactly the same type. A Count value can be used anywhere an int is expected, without conversion.

Shorten a qualified name

An alias can also shorten a name from another module:

use Geometry.Vector as Vector

In this file, Vector then designates Geometry.Vector. The alias neither moves the original declaration nor creates a wrapper or additional type identity.

Choose an alias when the new name better expresses the type's role or avoids repeating a long path. If two values must become incompatible despite an identical representation, an alias is insufficient: declare an actual type.

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