Result.ts

type Result<T> = {type: "ok", data: T} | {type: "error", reason: string};

export const ok = <T = unknown>(data: T): Result<T> => {
  return {type: "ok", data };
};

export const error = <T = unknown>(reason: string): Result<T> => {
  return {type: "error", reason};
};

export const isOk = <T = unknown>(r: Result<T>): boolean => {
  if (r.type !== "error")
    return true;
  return false;
};

export const isError = <T = unknown>(r: Result<T>): boolean => {
  if (r.type === "error")
    return true;
  return false;
};

export const map = <T = unknown, U = unknown>(r: Result<T>, fn: (v: T) => U): Result<U> => {
  switch(r.type) {
    case "ok":
      return {type: "ok", data: fn(r.data)};
    case "error":
      return r;
  }
};

export const chain = <T = unknown, U = unknown>(r: Result<T>, fn: (v: T) => Result<U>): Result<U> => {
  switch(r.type) {
    case "ok":
      return fn(r.data);
    case "error":
      return r;
  }  
};