Generic Type Alias

[RamIdeas]

What is the reason for disallowing generic type aliases?

I know you can use an empty interface definition to achieve the same thing, such as:

interface KO<T> extends KnockoutObservable<T> {}

But the limitation with interfaces is you can't use primitives or union types.

I want to be able to write:

type KnockoutWrapped<T> = T | KnockoutObservable<T>;
// or: type KW<T> = T | KO<T>;
// ensure I call ko.unwrap to get value

But my only option right now is:

type KnockoutWrappedString = string | KnockoutObservable<string>;
type KnockoutWrappedNumber = number | KnockoutObservable<number>;
type KnockoutWrappedBoolean = boolean | KnockoutObservable<boolean>;
// ...
// or:
type KWString = string | KO<string>;
type KWNumber = number | KO<number>;
type KWBoolean = boolean | KO<boolean>;

Which:

1. reduces my flexibility to use whatever type I want (without having to create more interfaces)
2. reduces readability as Visual Studio's colourisation won't colour string, number and boolean in blue, and
3. quite frankly, makes me type more -- reminiscent of back before typescript included generics and I was writing:

interface KOString extends KnockoutObservableString {}
interface KONumber extends KnockoutObservableNumber {}
interface KOBoolean extends KnockoutObservableBoolean {}
// ...

[danquirk]

See #1616