LookupTable.d.ts

import { UnionToIntersection } from 'utility-types';

type String<T> = T extends string ? T : any

type Keys<T, Field extends keyof T> =
  T extends { [P in Field]: infer A }
  ? { [P in String<A>]: T }
  : never

type LookupTable<Union, key extends keyof Union> = UnionToIntersection<Keys<Union, key>>

// usage
interface Slide {
  name: 'slide';
  key: 'foo'
  next(): void;
}
interface Pullup {
  name: 'pullup'; 
  key: 'bar'
  prev(): void;
}

type pullup = LookupTable<Slide|Pullup, 'name'>['pullup'] // Pullup
type slide = LookupTable<Slide | Pullup, 'key'>['foo'] // Slide