Can I write a type file for an observ-struct using jsig2?

[ajoslin]

Typescript is too inflexible to let me write a type for both the wrapped and unwrapped version of an observ-struct without writing two separate type definitions.

[Raynos]

@ajoslin

observ-struct : <K, I, V <: Observ<I>>(Record<K, V>) => Observ<Record<K, I>> & Record<K, V>

I want to implement Records; which allow you to operate over a set of keys and values.

TypeScript has a feature request for this https://github.com/Microsoft/TypeScript/issues/1295

Honestly; if I wanted to a do a well typed version of observ or observ-struct I would start changing the interface.

aka instead of:

var state = ObservStruct({
    fruits: ObservStruct({
        apples: Observ(3),
        oranges: Observ(5)
    }),
    customers: Observ(5)
})

// plain object
var state = {
  fruits: {
    apples: 3,
    oranges: 5
  },
  customers: 5
}

// ObservCursor : <T>(T) => Cursor<T>
var cursor = ObservCursor(state);

// get : <T>(this: Cursor<T>) => T
cursor.get();

// update : <T>(this: Cursor<T>, path: String, value: any) => void
cursor.update('fruits.apples', 4);

var state = {
  fruits: null,
  customers: 5
}
var rootCursor = ObservCursor(state);

var fruitsState = {
  apples: 3,
  oranges: 5
}
var fruitCursor = ObservCursor(fruitsState);

// merge : <T, S>(this: Cursor<T>, keyPath: String, Cursor<S>) => void
cursor.merge('fruits', fruitCursor);

I have no idea of this ObservCursor would work. I would hope that merge() allows us to get some of the cool features we wanted from arbitrarly nested observ...