Type aliasing
Type aliasing is a feature in some programming languages that allows the creation to refer to a type using another name. It does not create a new type hence does not increase type safety. It can be used to shorten a long name. Programing languages which allows type aliasing include C++, C# Crystal, D, Dart, Elixir, Elm, F#, Go, Hack, Haskell, Julia, Kotlin, Nim, OCaml, Python, Rust, Scala, Swift and TypeScript.
Example[edit]
C++[edit]
C++ features type aliasing using the using keyword.
using Distance = int;
C#[edit]
C# since version 12 features type aliasing using the using keyword.[1]
using Distance = int;
Crystal[edit]
Crystal features type aliasing using the alias keyword.[2]
alias Distance = Int32;
D[edit]
D features type aliasing using the alias keyword.[3]
alias Distance = int;
Dart[edit]
Dart features type aliasing using the typedef keyword.[4]
typedef Distance = int;
Elixir[edit]
Elixir features type aliasing using @type.[5]
@type Distance :: integer
Elm[edit]
Elm features type aliasing using type alias.
type alias Distance = Int
F#[edit]
F3 features type aliasing using the type keyword.
type Distance = int
Go[edit]
Go features type aliasing using the type keyword.
type Distance int
Hack[edit]
Hack features type aliasing using the newtype keyword.[6]
newtype Distance = int;
Haskell[edit]
Haskell features type aliasing using the type keyword.[7]
type Distance = Int;
Julia[edit]
Julia features type aliasing.[8]
const Distance = Int
Kotlin[edit]
Kotlin features type aliasing using the typealias keyword.[9]
typealias Distance = Int
Nim[edit]
Nim features type aliasing.[10]
type
Distance* = int
OCaml[edit]
OCaml features type aliasing.[11]
type distance = int
Python[edit]
Python features type aliasing.[12]
Vector = list[float]
Type aliases may be marked with TypeAlias to make it explicit that the statement is a type alias declaration, not a normal variable assignment.
from typing import TypeAlias
Vector: TypeAlias = list[float]
Rust[edit]
Rust features type aliasing using the type keyword.[13]
type Point = (u8, u8);
Scala[edit]
Scala can create type aliases using opaque types.[14]
object Logarithms:
opaque type Logarithm = Double
Swift[edit]
Swift features type aliasing using the typealias keyword.
typealias Distance = Int;
TypeScript[edit]
TypeScript features type aliasing using the type keyword.[15]
type Distance = number;
References[edit]
- ^ "Alias any type - C# 12.0 draft feature specifications". learn.microsoft.com. 16 August 2023. Retrieved 23 February 2024.
- ^ "alias - Crystal". crystal-lang.org. Retrieved 21 February 2024.
- ^ "Alias Alias - D Programming Language". dlang.org. Retrieved 18 June 2023.
- ^ "Typedefs". dart.dev. Retrieved 18 June 2023.
- ^ "Typespecs and behaviours". elixir-lang.github.com. Retrieved 23 June 2023.
- ^ "Types: Type Aliases". docs.hhvm.com. Retrieved 18 June 2023.
- ^ "Type synonym - HaskellWiki". wiki.haskell.org. Retrieved 18 June 2023.
- ^ "Types · The Julia Language". docs.julialang.org. Retrieved 23 June 2023.
- ^ "Type aliases | Kotlin". Kotlin Help. Retrieved 18 June 2023.
- ^ "Nim by Example - Types". nim-by-example.github.io. Retrieved 21 June 2023.
- ^ "OCaml reference manual". ocaml.org. Retrieved 23 April 2024.
- ^ "typing — Support for type hints". Python documentation. Python Software Foundation. Retrieved 18 June 2023.
- ^ "Type aliases - The Rust Reference". doc.rust-lang.org. Retrieved 18 June 2023.
- ^ "Opaque Types". Scala Documentation. Retrieved 18 June 2023.
- ^ "Documentation - Everyday Types". www.typescriptlang.org. Retrieved 18 June 2023.