typescript generic snippet

types-snippet.ts

// mapping
enum Words {
  One = 'one',
  Two = 'two',
  Three = 'three',
}
 
enum Numbers {
  One = 1,
  Two = 2,
  Three = 3,
}

type _WordToNumber<Object extends {[Word in Words]: Numbers}> = Object

type WordToNumber1 = _WordToNumber<{
  [Words.One]: Numbers.One,
  [Words.Two]: Numbers.Two,
  [Words.Three]:Numbers.Three
}>

type OneWordAsNumber = WordToNumber1[Words.One]


// validation
type DiceSides = 4 | 6 | 8 | 10 | 12 | 20

type DiceString<
  Count extends number,
  Sides extends DiceSides,
> = `${Count}d${Sides}`

type TwoDFour = DiceString<2,4>


type DiceStringToDiceRoll<String extends string> =
  String extends `${infer Count extends number}d${infer Sides extends DiceSides}`
    ? {count: Count; sides: Sides}
    : never
 
type TwoDFourRoll = DiceStringToDiceRoll<'2d4'>