splitEvery typings are wrong

[codan84]

splitEvery takes 2 arguments and is curried so the following is possible:

splitEvery(2, [1,2,3,4,5,6])

splitEvery(2)([1,2,3,4,5,6])

However, your types are messed up making it hard to work with in TS:

export function splitEvery(a: number): {
  (list: string): string[];
  <T>(list: readonly T[]): T[][];
};
export function splitEvery(a: number, list: string): string[];
export function splitEvery<T>(a: number, list: readonly T[]): T[][];

Should be corrected to:

export function splitEvery(a: number, list: string): string[];
export function splitEvery(a: number): (list: string) => string[]

export function splitEvery<T>(a: number, list: readonly T[]): T[][];
export function splitEvery<T>(a: number): (list: readonly T[]) => T[][];

[Harris-Miller]

export function splitEvery(a: number, list: string): string[];
export function splitEvery(a: number): (list: string) => string[]

export function splitEvery<T>(a: number, list: readonly T[]): T[][];
export function splitEvery<T>(a: number): (list: readonly T[]) => T[][];

This won't work for a few reasons.

First. Typescript expects the most specific first and the most generic last. The generic last is for general fall back and because that is the typedef that gets passed if you pass the function as an argument

Second, typescript tries to match first defined. This means that it will find export function splitEvery(a: number): (list: string) => string[] first, and splitEvery(2)([1,2,3,4,5,6]) will never be allowed. Because [1,2,3,4,5,6]. Typescript will not go back and look for the other def export function splitEvery<T>(a: number): (list: readonly T[]) => T[][]; to match what you're trying to give it

This is why we define it like this:

export function splitEvery(a: number): {
  (list: string): string[];
  <T>(list: readonly T[]): T[][];
};

This is says that splitEvery(2) returns a function that can accept either a string or T[] as it's arg, return the correct return type depending.

The current type definition is correct as is. Closing