tiny-decoders

tiny-decoders

Type-safe data decoding for the minimalist.

➡️ Full readme

Changelog

Version 10.0.0 (2023-10-15)

Changed: multi has a new API.

Before:

type Id = { tag: "Id"; id: string } | { tag: "LegacyId"; id: number };

const idDecoder: Decoder<Id> = multi({
  string: (id) => ({ tag: "Id" as const, id }),
  number: (id) => ({ tag: "LegacyId" as const, id }),
});

After:

type Id = { tag: "Id"; id: string } | { tag: "LegacyId"; id: number };

const idDecoder: Decoder<Id> = chain(multi(["string", "number"]), (value) => {
  switch (value.type) {
    case "string":
      return { tag: "Id" as const, id: value.value };
    case "number":
      return { tag: "LegacyId" as const, id: value.value };
  }
});

Like before, you specify the types you want (string and number above), but now you get a tagged union back ({ type: "string", value: string } | { type: "number", value: number }) instead of supplying functions to call for each type. You typically want to pair this with chain, switching on the different variants of the tagged union.

This change unlocks further changes that will come in future releases.