Infer type from field

TypeUtil.ts

export function withType<TElement extends { __type: string }, TType extends TElement["__type"]>(
  elements: TElement[],
  type: TType
): Extract<TElement, { __type: TType }>[] {
  return elements?.filter(element => element.__type === type) as Extract<TElement, { __type: TType }>[]
}

export function withoutType<TElement extends { __type: string }, TType extends TElement["__type"]>(
  elements: TElement[],
  type: TType
): Exclude<TElement, { __type: TType }>[] {
  return elements?.filter(element => element.__type !== type) as Exclude<TElement, { __type: TType }>[]
}