Typescript - Prettify intelli-sense, Make certain fields from type T as partial & others as required and group-by array elements type

utility_types.ts

/**
 * Prettify the hover output of a type
 */
export type Prettify<T> = {
	[K in keyof T]: T[K]
} & {}

/**
 * Make certain fields from T as partial
 */
export type PartialCertain<T, K extends keyof T> = Prettify<Required<Omit<T, K>> & Partial<Pick<T, K>>>

/**
 * Make a string as plural by adding a suffix
 */
export type Pluralize<S extends string> = `${S}s`;

/**
 * Group an array by it's elements
 */
export type GroupByArray<T extends any[]> = Prettify<{
	[K in keyof T[number] as Pluralize<string & K>]: Extract<T[number], { [P in K]: T[K] }>[K][]
}>