Not very useful implementation of Char in TypeScript

char.ts

const chartag = Symbol("char");
export type Char = string & { __tag: typeof chartag };


type IsChar<S extends string> = S extends `${infer Head}${infer Tail}`
  ? Head extends ""
    ? never
    : Tail extends ""
    ? Char 
    : never
  : never;

type C = IsChar<"c">; // Char

type CC = IsChar<"cc">; // never

type EC = IsChar<"">; // never