TypeScript to F#
What each TypeScript construct is generated as.
Declarations
| TypeScript | F# |
|---|
function f(): void | static member f () : unit on Exports, with Import |
const x: number | static member inline x: float on Exports |
class C | interface C, and static member C () on Exports with EmitConstructor |
static member of a class | static member inline on the interface, emitted as JavaScript |
interface I | [<AllowNullLiteral>] [<Interface>] type I |
type A = B | type A = B |
namespace N | module N, its values on N.Exports |
enum E { A = 1 } | type E = A = 1 |
enum E { A = "a" } | [<StringEnum>] type E = A |
enum E { A = "a", B = 1 } | [<Erase>] type E = String of string | Number of float, with a constant per member |
export = f | Exports.f, through the default import |
export default C | the declaration, through the default import |
export as namespace N | nothing |
declare global | a global_ module |
Members
| TypeScript | F# |
|---|
x: T | abstract member x: T with get, set |
readonly x: T | abstract member x: T with get |
x?: T | abstract member x: T option with get, set |
m(a: A): R | abstract member m: a: A -> R |
m(a?: A) | abstract member m: ?a: A -> R |
m(...a: A[]) | [<ParamArray>] a: A [] |
get x(): T and set x(v: T) | one property |
[key: string]: T | [<EmitIndexer>] abstract member Item: key: string -> T |
new (a: A): R | [<EmitConstructor>] abstract member Create: a: A -> R |
(a: A): R call signature | [<Emit("$0($1...)")>] abstract member Invoke: a: A -> R |
m(this: T, a: A) | abstract member m: a: A -> R |
m<T>(a: T): T | abstract member m<'T>: a: 'T -> 'T |
m<T = D>() | the member, and an overload without T with D in its place |
| overloads | one member per overload |
Types
| TypeScript | F# |
|---|
string, number, boolean | string, float, bool |
bigint | bigint |
void, undefined | unit, obj |
any, unknown, never, symbol | obj |
T[], Array<T> | ResizeArray<T> |
readonly T[] | ReadonlyArray<T>, ResizeArray<T> as a parameter, a union case or a callback return |
[A, B] | A * B |
[A, ...B[]] | ResizeArray<obj> |
type X = A | B | an erased union X with the cases X.A, X.B and the accessors AsA, AsB |
A | B in a parameter | one overload per case, up to 16 combinations, then U2<A, B> |
A | B elsewhere | U2<A, B>, up to U9 |
| more than nine cases | obj |
"a" | B, literals and types | an erased union, its literals named and its types numbered [<RequireQualifiedAccess>]
[<Erase(CaseRules.None)>]
type T =
| a
| Case1 of B
|
"a" | "b" | a StringEnum type |
1 | 2 | an enum type |
true | false | bool |
T | undefined, T | null | T option |
(a: A) => R | A -> R |
(a: A, b: B) => R | a delegate of a: A * b: B -> R |
type F = (a: A) => R | type F = A -> R |
{ x: T } in a parameter | a class with a ParamObject constructor |
{ x: T } elsewhere | an interface in the module of the parent |
Date | Date of Glutinum.Types, built with Date.Create |
Promise<T>, RegExp | JS.Promise<T>, RegExp |
Map<K, V>, Set<T> | Map<K, V>, Set<T> from Fable.Core.JS |
HTMLElement and the DOM | Glutinum.Web.HTMLElement |
Buffer and the Node API | Glutinum.Node.Buffer |
typeof x | the type of x |
keyof T, T known | a StringEnum of its keys |
T[K], T known | the type of the member |
`on${K}` | a StringEnum when it enumerates |
x is T | bool |
asserts x is T | unit |
T extends U ? A : B | A or B when decided, obj otherwise |
Partial<T> | the members of T, optional |
Required<T>, Pick<T, K>, Omit<T, K> | the members it keeps |
Record<K, V> | an interface with an indexer |
Readonly<T> | the members of T, read only |
ReturnType<F>, Parameters<F>, Awaited<T> | the resolved type |
Exclude<T, undefined> | T |
| a mapped type over a type parameter | obj |
a generic type parameter T extends C | 'T |