gistfile1.js

interface Functor {
	fmap: (any) => any;
}

interface Monad extends Functor {
	bind: (any) => Monad;
}

interface Maybe extends Monad {
}

class Just implements Maybe {
	private value: any;
	constructor(a: any) {
		this.value = a
	}
	fmap (f: (any) => any): Just {
		return new Just(f(this.value))
	}
	bind (f: (any) => Maybe): Maybe {
		return f(this.value)
	}
}

class Nothing implements Maybe {
	fmap (f: (any) => any): Nothing {
		return this
	}
	bind (f: (any) => Maybe): Maybe {
		return this
	}
}