index.ts

import { fromJson as fromResultJson } from "@/lib/true-myth/result";
import { fromJson as fromMaybeJson } from "@/lib/true-myth/maybe";

export function unreachable(value: never): never {
  throw new Error(`Should have been unreachable with ${value}`);
}

export { fromResultJson, fromMaybeJson };

maybe.ts

import { unreachable } from "@/lib/true-myth";
import Maybe, * as maybe from "true-myth/maybe";

export function fromJson<T extends object>(json: maybe.MaybeJSON<T>): Maybe<T> {
  switch (json.variant) {
    case "Just":
      return Maybe.just(json.value);
    case "Nothing":
      return Maybe.nothing();
    default:
      unreachable(json);
  }
}

result.ts

import { unreachable } from "@/lib/true-myth";
import Result, * as result from "true-myth/result";

export function fromJson<T, E>(json: result.ResultJSON<T, E>): Result<T, E> {
  switch (json.variant) {
    case "Ok":
      return Result.ok(json.value);
    case "Err":
      return Result.err(json.error);
    default:
      unreachable(json);
  }
}