Mutable

Use ft.Mutable to change an array or object Codec from readonly to mutable. It will not have any effect on the actual behaviour of the Codec, other than the results of ft.showType and the inferred TypeScript type.

The inverse is also available as ft.Readonly

Mutable Array

import * as ft from "funtypes";

const ReadonlyArrayCodec = ft.ReadonlyArray(
  ft.Number,
);
// => Codec<readonly number[]>

const ArrayCodec = ft.Mutable(ReadonlyArrayCodec);
// => Codec<number[]>

type Array = ft.Static<typeof ArrayCodec>;
// => number[]

assert.deepEqual(
  ft.showType(ArrayCodec),
  "number[]",
);

Mutable Object

import * as ft from "funtypes";

const ReadonlyUserCodec = ft.ReadonlyObject({
  id: ft.Number,
  name: ft.String,
});
// => Codec<{ readonly id: number; readonly name: string }>

const UserCodec = ft.Mutable(ReadonlyUserCodec);
// => Codec<{ id: number; name: string }>

type User = ft.Static<typeof UserCodec>;
// => { id: number; name: string }

assert.deepEqual(
  ft.showType(UserCodec),
  "{ id: number; name: string }",
);

Mutable Tuple

import * as ft from "funtypes";

const ReadonlyTupleCodec = ft.ReadonlyTuple(
  ft.Number,
  ft.String,
);
// => Codec<readonly [ number, string ]>

const TupleCodec = ft.Mutable(ReadonlyTupleCodec);
// => Codec<[ number, string ]>

type Tuple = ft.Static<typeof TupleCodec>;
// => [ number, string ]

assert.deepEqual(
  ft.showType(TupleCodec),
  "[ number, string ]",
);