Missing solution for dictionary challenge

[hatched-cristina]

The instructor mentions at the end of "Dictionary Solution" lesson that it will be available on the repo, but I don't see it there. After contacting support via Intercom, I was directed to leave an issue on the repo. Thanks!

I would imagine it would be this file, but filled in https://github.com/mike-works/typescript-fundamentals/blob/362113346f26fde233919a04a9e8a87f81c8e319/challenges/dict/src/index.ts

[jubeater]

here is the sol i have(map from video, reduce just mocked the map style)

export type Dict<T> = {
    [anyKeyWeWant: string]: T | undefined;
};

// Array.prototype.map, but for Dict
export function mapDict<T, S>(
    dict: Dict<T>,
    fn: (arg: T, idx: number) => S
): Dict<S> {
    const out: Dict<S> = {};
    Object.keys(dict).forEach((keyName, idx: number) => {
        const thisItem = dict[keyName];
        if (typeof thisItem !== 'undefined') {
            out[keyName] = fn(thisItem, idx);
        };
    });
    return out;
}

// Array.prototype.reduce, but for Dict
export function reduceDict<T, S>(
    dict: Dict<T>,
    fn: (cur: T, sum: S) => S,
    initVal: S
): S {
    let out: S = initVal;
    Object.keys(dict).forEach((keyName) => {
        const thisItem = dict[keyName];
        if (typeof thisItem !== 'undefined') {
            out = fn(thisItem, out);
        };
    });
    return out;
}

[it3xl]

Oh, many thanks.

Couple of thoughts.

To make tests compilable after

it("(compile) should have a default typeParam", () => {
    ...
it("(compile) should have a default typeParam of `any`", () => {

we have to replace type Dict<T> with type Dict<T = any>

export type Dict<T = any> = {
    [k:string]: T | undefined;
};

Btw, we don't always use summation in reducers. A more general term is aggregation, IMHO.
I would use aggr in place of sum, i.e. fn: (cur: T, aggr: S) => S, in place of fn: (cur: T, sum: S) => S,.
But then fn would be more expressive the same as Array.prototype.reduce.