67c6cebfc8
* Reinterpret a type parameter constrained to any as an upper bound constraint * Use real constraqint in alias in test Co-authored-by: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>
67 lines
2.1 KiB
TypeScript
67 lines
2.1 KiB
TypeScript
// @strict: true
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type Either<L, A> = Left<L, A> | Right<L, A>;
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class Left<L, A> {
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readonly _tag: 'Left' = 'Left'
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readonly _A!: A
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readonly _L!: L
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constructor(readonly value: L) {}
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/** The given function is applied if this is a `Right` */
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map<B>(f: (a: A) => B): Either<L, B> {
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return this as any
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}
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ap<B>(fab: Either<L, (a: A) => B>): Either<L, B> {
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return null as any
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}
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}
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class Right<L, A> {
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readonly _tag: 'Right' = 'Right'
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readonly _A!: A
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readonly _L!: L
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constructor(readonly value: A) {}
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map<B>(f: (a: A) => B): Either<L, B> {
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return new Right(f(this.value))
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}
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ap<B>(fab: Either<L, (a: A) => B>): Either<L, B> {
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return null as any;
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}
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}
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class Type<A, O = A, I = unknown> {
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readonly _A!: A;
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readonly _O!: O;
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readonly _I!: I;
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constructor(
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/** a unique name for this codec */
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readonly name: string,
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/** a custom type guard */
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readonly is: (u: unknown) => u is A,
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/** succeeds if a value of type I can be decoded to a value of type A */
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readonly validate: (input: I, context: {}[]) => Either<{}[], A>,
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/** converts a value of type A to a value of type O */
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readonly encode: (a: A) => O
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) {}
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/** a version of `validate` with a default context */
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decode(i: I): Either<{}[], A> { return null as any; }
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}
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interface Any extends Type<any, any, any> {}
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type TypeOf<C extends Any> = C["_A"];
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type ToB<S extends {[_ in string | number | symbol]: Any}> = { [k in keyof S]: TypeOf<S[k]> };
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type ToA<S> = { [k in keyof S]: Type<S[k]> };
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type NeededInfo<MyNamespaceSchema = {}> = {
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ASchema: ToA<MyNamespaceSchema>;
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};
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export type MyInfo = NeededInfo<ToB<{ initialize: any }>>;
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const tmp1: MyInfo = null!;
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function tmp2<N extends NeededInfo>(n: N) {}
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// tmp2(tmp1); // uncommenting this line removes a type error from a completely unrelated line ?? (see test 1, needs to behave the same)
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class Server<X extends NeededInfo> {}
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export class MyServer extends Server<MyInfo> {} // not assignable error at `MyInfo`
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