Custom signals support

[Marcelo Terreiro Prado]

After reading the Custom Type docs, I tried creating a custom date signal. I'm not sure the right way of injecting custom assert functions. For example, the number operator adds its own set of functions. I would like to do the same for my types.

For example:

const dateSignal = signal.type<Date>(z.date().parse)

I'm trying to understand how to enhance its types to support operations besides the basic ones:

Given dates are a non-trivial type, it would be awesome if I could add operations like isSameDay, isAfter, isBefore, etc.

[Marcelo Terreiro Prado]

Turns out I can build a similar feature by using a regular number signal:

  dayOfMonth: signal.number.value<Date>((value) => getDate(value)),
  dayOfWeek: signal.number.value<Date>((value) => getISODay(value)),

Then, I can use the number assertions to achieve my goal.

Nonetheless, I'm really curious if my idea above is even possible. I've looked at the internals, but I need some time to get familiar with the TS gymnastics that happens in the signal/factory.ts 😂