Suggestion: use `:{type}` to omit formal parameter when declare function interface or something else

[wyntau]

When we declare a function interface, omit formal parameter. Because the param name is not important in interface, just the param type does.

So, we can make below code

interface func{
    (paramA: typeA, paramB: typeB): typeC;
}

to this form

interface func{
    (:typeA, :typeB): typeC
}

[kitsonk]

The formal parameter name is often useful for intellisense when using semantically meaningful parameter names, is it not?

[RyanCavanaugh]

I mean, you can't stop someone from not providing a useful name. p0, p1, p2, etc.

[wyntau]

I mean, TypeScript can support this form but it's optional. So someone can omit the formal parameter name. Because sometime we don't know the correct parameter name until we implement it

[yortus]

There are situations like this where omitting some parameter names would be a small mercy. But that particular pattern will hopefully one day be addressed better by something like #5453.

In general there are cases where the intent of declaring a function type is purely to describe a mapping from certain parameter type(s) to a certain return type, and giving names to the parameters is mostly meaningless boilerplate. You can see some of these in ramda.d.ts.

Basically any situation where you'd be temped to name things arg1, arg2 and so on would be candidates for this proposal. The compiler would probably internally name them arg1, arg2 etc for intellisense anyway.

[RyanCavanaugh]

We'd really like people to try hard to come up with parameter names, and this syntax looks really weird on its own (is it a weird kind of parameter name? a destructuring? something else?) so we'd prefer to keep names mandatory at this point.