sendou.ink/openskill.d.ts

type Rating = {
  mu: number;
  sigma: number;
};

declare module "openskill" {
  export function rating(rating?: Rating): Rating;
  export function ordinal(rating: Rating): number;
  export function rate(
    ratings: [Rating[], Rating[]],
    options: { tau: number; preventSigmaIncrease: boolean }
  ): [Rating[], Rating[]];
}