Support TS 4.7 instantiation expressions

[cyberia-ng]

TS 4.7.0 (currently in beta) will bring in "Instantiation Expressions" (see https://github.com/microsoft/TypeScript/pull/47607).

Essentially this means that you can write things like:

function foo<T>(val: T) {}
type Foo<T> = typeof foo<T>
// type Foo<T> = (val: T) => void

The application for Zod schemas is as detailed here (https://github.com/microsoft/TypeScript/issues/40542), in particular that we can now write such things as:

// the dateSchema param could be a schema for an ISO 8601 string or a Date object, or even some custom date-like type
const fooSchema = <T>(dateSchema: z.ZodSchema<T>) => z.object({
  name: z.string(),
  date: dateSchema
})
type Foo<T> = z.infer<ReturnType<(typeof fooSchema)<T>>>
// expected result: type Foo<T> = { name: string, date: T }

Unfortunately this does not "Just Work" by upgrading to TS 4.7.0-beta:

import { z } from "zod";

function genericFooSchema<T>(inner: z.Schema<T>) {
  return z.object({
    type: z.literal("foo"),
    inner,
  });
}

type Foo<T> = z.infer<ReturnType<typeof genericFooSchema<T>>>;

function useAFoo<T>(foo: Foo<T>): string {
  switch (foo.type) {
    // Hovering over foo.type gives:
    // ```
    // (property) type: z.objectUtil.addQuestionMarks<{
    //     type: "foo";
    //     inner: T;
    // }>["type"]
    // ```

    case "foo":
      return "TS should infer that this switch is exhaustive";
  }
}

[cyberia-ng]

Related: https://github.com/colinhacks/zod/issues/153

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[aganoza]

bump

[max-abclabs]

Since typescript's official version is now, as of this writing, 4.7.4 would it be possible to prioritise this feature now?

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[dilame]

Hey guys, why is this issue closed?

[FlorianWendelborn]

@dilame as you can see, it is closed because @stale decided to close it and nobody cared enough to bump