schema to static magic

schema.ts

export const tString : 'string' = 'string';
export const tNumber : 'number' = 'number';

export interface TypeMap {
    'number': number;
    'string': string
}

export type Schema = {
    [fieldName: string]: {type: "string" | "number"}
}

export type Static<T extends Schema> = {
    [fieldName in keyof T]: TypeMap[T[fieldName]["type"]]
}

user.ts

improt { Schema, Static, tString, tNumber } from './schema.ts';
  
const User = {
 id: {type: tNumber},
 username: {type: tString}
}

type UserType = Static<typeof User>;

let user1 : UserType = {
    id: 123,
    username: "abc"  // all good
    // <ctrl+space> autocompletion provides "id" and "username" options
}
  
let user2 : UserType = {
    id: 'abc',
    username: 123
    // [ts]
    // Type '{ id: string; username: number; }' is not assignable to type 'Static<{ id: { type: "number"; }; username: { type: "string"; }; }>'.
    // Types of property 'id' are incompatible.
    // Type 'string' is not assignable to type 'number'.
}