TypeScript映射类型 - 如何获取嵌套对象的类型

Question

TypeScript 2.1具有Mapped Types的强大功能，可以键入对象的键并通过键获取类型。例如，您可以更改原始对象的结构：

type FactoryUnit<T> = {
    self: T;
};

type Factory<T> = {
    compile: () => {[P  in keyof T]: FactoryUnit<T[P]>};
    clone: (mutator: (origin: T) => T) => Factory<T>;
};

function buildFactory<T>(v: T): Factory<T> {
    return null;
}

const imp = buildFactory({ one: 1, two: 2 }).compile();
console.log(imp.one.self);

但是如果我想改变里面的物体怎么办？例如，我确信对象值具有modifiers属性，我可以使用某些函数来使用它。

type FactoryUnit<T, M> = {
    self: T;
    modifiers: <R>(f: (v: M) => R) => R;
};

type Factory<T extends { [key: string]: { modifiers: M } }, M> = {
    compile: () => {[P  in keyof T]: FactoryUnit<T[P], T[P]['modifiers']>};
    clone: (mutator: (origin: T) => T) => Factory<T, M>;
};

function buildFactory<T extends { [key: string]: { modifiers: M } }, M>(v: T): Factory<T, M> {
    return null;
}

const imp = buildFactory({
    one: { one: 1, modifiers: { mOne: 11 } },
    two: { two: 2, modifiers: { mTwo: 11 } }
}).compile();

console.log(imp.one.modifiers(v => v.mOne)); // v is any

我试图告诉TypeScript关于modifiers键，但是如何键入值以使ts推断它？如何告诉TypeScript modifiers属性有M类型？