fancytypes.ts

export type Discriminate<T, TField extends keyof T, TValue extends T[TField]> = T extends {[field in TField]: TValue}
  ? T
  : never;
type UnionToIntersection<U> = (U extends any ? (k: U) => void : never) extends (k: infer I) => void ? I : never;
type IsUnion<T, U extends T = T> = T extends unknown ? ([U] extends [T] ? false : true) : false;
type IsStringUnion<T> = IsUnion<T> extends true ? (T extends string ? true : false) : false;