TypeScript/tests/baselines/reference/discriminatedUnionFlatMap.types at 96faf0a3aea3047945dbb68782b73c0e07e3e7f9 · jakebailey/TypeScript · GitHub

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//// [tests/cases/compiler/discriminatedUnionFlatMap.ts] ////

=== discriminatedUnionFlatMap.ts ===
// https://github.com/microsoft/typescript-go/issues/1057

export type InputOp = { op: "add" } | { op: "remove"; value?: Array<unknown> };
>InputOp : InputOp
>        : ^^^^^^^
>op : "add"
>   : ^^^^^
>op : "remove"
>   : ^^^^^^^^
>value : unknown[] | undefined
>      : ^^^^^^^^^^^^^^^^^^^^^

export type OutputOp = { op: "add" | "remove" };
>OutputOp : OutputOp
>         : ^^^^^^^^
>op : "add" | "remove"
>   : ^^^^^^^^^^^^^^^^

export function f(operations: InputOp[]): OutputOp[] {
>f : (operations: InputOp[]) => OutputOp[]
>  : ^          ^^         ^^^^^
>operations : InputOp[]
>           : ^^^^^^^^^

    return operations.flatMap((operation) => {
>operations.flatMap((operation) => {        if (operation.op === "remove" && operation.value) {            return [].map(() => ({ op: "remove" }));        } else {            return [operation];        }    }) : InputOp[]
>                                                                                                                                                                                                                 : ^^^^^^^^^
>operations.flatMap : <U, This = undefined>(callback: (this: This, value: InputOp, index: number, array: InputOp[]) => U | readonly U[], thisArg?: This | undefined) => U[]
>                   : ^ ^^    ^^^^^^^^^^^^^^        ^^^    ^^^^^^^^     ^^^^^^^^^^^     ^^      ^^     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^       ^^^^^^^^^^^^^^^^^^^^^^^^^^^
>operations : InputOp[]
>           : ^^^^^^^^^
>flatMap : <U, This = undefined>(callback: (this: This, value: InputOp, index: number, array: InputOp[]) => U | readonly U[], thisArg?: This | undefined) => U[]
>        : ^ ^^    ^^^^^^^^^^^^^^        ^^^    ^^^^^^^^     ^^^^^^^^^^^     ^^      ^^     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^       ^^^^^^^^^^^^^^^^^^^^^^^^^^^
>(operation) => {        if (operation.op === "remove" && operation.value) {            return [].map(() => ({ op: "remove" }));        } else {            return [operation];        }    } : (this: undefined, operation: InputOp) => InputOp[] | { op: "remove"; }[]
>                                                                                                                                                                                             : ^    ^^^^^^^^^^^^^         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>operation : InputOp
>          : ^^^^^^^

        if (operation.op === "remove" && operation.value) {
>operation.op === "remove" && operation.value : false | unknown[] | undefined
>                                             : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>operation.op === "remove" : boolean
>                          : ^^^^^^^
>operation.op : "add" | "remove"
>             : ^^^^^^^^^^^^^^^^
>operation : InputOp
>          : ^^^^^^^
>op : "add" | "remove"
>   : ^^^^^^^^^^^^^^^^
>"remove" : "remove"
>         : ^^^^^^^^
>operation.value : unknown[] | undefined
>                : ^^^^^^^^^^^^^^^^^^^^^
>operation : { op: "remove"; value?: Array<unknown>; }
>          : ^^^^^^        ^^^^^^^^^^              ^^^
>value : unknown[] | undefined
>      : ^^^^^^^^^^^^^^^^^^^^^

            return [].map(() => ({ op: "remove" }));
>[].map(() => ({ op: "remove" })) : { op: "remove"; }[]
>                                 : ^^^^^^^^^^^^^^^^^^^
>[].map : <U>(callbackfn: (value: never, index: number, array: never[]) => U, thisArg?: any) => U[]
>       : ^ ^^          ^^^     ^^^^^^^^^     ^^      ^^     ^^^^^^^^^^^^^^^^^       ^^^   ^^^^^^^^
>[] : never[]
>   : ^^^^^^^
>map : <U>(callbackfn: (value: never, index: number, array: never[]) => U, thisArg?: any) => U[]
>    : ^ ^^          ^^^     ^^^^^^^^^     ^^      ^^     ^^^^^^^^^^^^^^^^^       ^^^   ^^^^^^^^
>() => ({ op: "remove" }) : () => { op: "remove"; }
>                         : ^^^^^^^^^^^^^^^^^^^^^^^
>({ op: "remove" }) : { op: "remove"; }
>                   : ^^^^^^^^^^^^^^^^^
>{ op: "remove" } : { op: "remove"; }
>                 : ^^^^^^^^^^^^^^^^^
>op : "remove"
>   : ^^^^^^^^
>"remove" : "remove"
>         : ^^^^^^^^

        } else {
            return [operation];
>[operation] : InputOp[]
>            : ^^^^^^^^^
>operation : InputOp
>          : ^^^^^^^
        }
    });
}