Add AugmentedMutable type

README.md

@@ -115,7 +115,7 @@ We are open for contributions. If you're planning to contribute please make sure
 * [`DeepRequired<T>`](#deeprequiredt)
 * [`Readonly<T>`](#readonlyt) _(built-in)_
 * [`DeepReadonly<T>`](#deepreadonlyt)
-* [`Mutable<T>`](#mutablet)
+* [`Mutable<T, K>`](#mutablet-k)
 * [`Pick<T, K>` _(built-in)_](#pickt-k-built-in)
 * [`Omit<T, K>`](#omitt-k) _(built-in)_
 * [`PickByValue<T, ValueType>`](#pickbyvaluet-valuetype)
@@ -678,11 +678,11 @@ Make all properties of object type readonly
 
 [⇧ back to top](#table-of-contents)
 
-### `Mutable<T>`
+### `Mutable<T, K>`
 
-From `T` make all properties become mutable
+From `T`, make a set of properties, whose keys are in the union `K`, mutable
 
-Alias: `Writable<T>`
+Alias: `Writable<T, K>`
 
 ```ts
 import { Mutable } from 'utility-types';
@@ -695,6 +695,9 @@ type Props = {
 
 // Expect: { name: string; age: number; visible: boolean; }
 Mutable<Props>;
+
+// Expect: { readonly name: string; age: number; visible: boolean; }
+Mutable<Props, 'age' | 'visible'>;
 ```
 
 [⇧ back to top](#table-of-contents)

src/__snapshots__/mapped-types.spec.ts.snap

@@ -4,6 +4,24 @@ exports[`Assign const result: Assign<{}, Omit<T, 'age'>> = rest (type) should ma
 
 exports[`Assign testType<Assign<Props, NewProps>>() (type) should match snapshot 1`] = `"Pick<Pick<Props, \\"name\\" | \\"visible\\"> & Pick<NewProps, \\"age\\"> & Pick<NewProps, \\"other\\">, \\"name\\" | \\"age\\" | \\"visible\\" | \\"other\\">"`;
 
+exports[`AugmentedMutable testType<AugmentedMutable<Readonly<Props>, 'name' | 'age'>>({
+ name: 'Yolo',
+ age: 99,
+ visible: true,
+ }) (type) should match snapshot 1`] = `"AugmentedMutable<Readonly<Props>, \\"name\\" | \\"age\\">"`;
+
+exports[`AugmentedMutable testType<AugmentedMutable<Readonly<Props>>>({
+ name: 'Yolo',
+ age: 99,
+ visible: true,
+ }) (type) should match snapshot 1`] = `"AugmentedMutable<Readonly<Props>, \\"name\\" | \\"age\\" | \\"visible\\">"`;
+
+exports[`AugmentedMutable testType<AugmentedMutable<Readonly<Props>>['age']>(99) (type) should match snapshot 1`] = `"number"`;
+
+exports[`AugmentedMutable testType<AugmentedMutable<Readonly<Props>>['name']>('Yolo') (type) should match snapshot 1`] = `"string"`;
+
+exports[`AugmentedMutable testType<AugmentedMutable<Readonly<Props>>['visible']>(true) (type) should match snapshot 1`] = `"boolean"`;
+
 exports[`AugmentedRequired testType<AugmentedRequired<Partial<Props>, 'age' | 'visible'>>({
  age: 99,
  visible: true,
@@ -111,18 +129,6 @@ exports[`Intersection testType<Intersection<Props | NewProps, DefaultProps>>() (
 
 exports[`Intersection testType<Intersection<Props, DefaultProps>>() (type) should match snapshot 1`] = `"Pick<Props, \\"age\\">"`;
 
-exports[`Mutable testType<Mutable<Readonly<Props>>>({
- name: 'Yolo',
- age: 99,
- visible: true,
- }) (type) should match snapshot 1`] = `"Mutable<Readonly<Props>>"`;
-
-exports[`Mutable testType<Mutable<Readonly<Props>>['age']>(99) (type) should match snapshot 1`] = `"number"`;
-
-exports[`Mutable testType<Mutable<Readonly<Props>>['name']>('Yolo') (type) should match snapshot 1`] = `"string"`;
-
-exports[`Mutable testType<Mutable<Readonly<Props>>['visible']>(true) (type) should match snapshot 1`] = `"boolean"`;
-
 exports[`MutableKeys testType<MutableKeys<ReadWriteProps>>() (type) should match snapshot 1`] = `"\\"b\\""`;
 
 exports[`NonFunctionKeys testType<NonFunctionKeys<MixedProps>>() (type) should match snapshot 1`] = `"\\"name\\" | \\"someKeys\\""`;

src/index.ts

@@ -27,7 +27,7 @@ export {
  Diff,
  FunctionKeys,
  Intersection,
- Mutable,
+ AugmentedMutable as Mutable,
  MutableKeys,
  NonFunctionKeys,
  NonUndefined,

src/mapped-types.spec.snap.ts

@@ -40,7 +40,7 @@ import {
  ValuesType,
  AugmentedRequired,
  UnionToIntersection,
- Mutable,
+ AugmentedMutable,
 } from './mapped-types';
 
 /**
@@ -572,21 +572,28 @@ type RequiredOptionalProps = {
  testType<UnionToIntersection<'name' | 'age'>>();
 }
 
-// @dts-jest:group Mutable
+// @dts-jest:group AugmentedMutable
 {
- // @dts-jest:pass:snap -> Mutable<Readonly<Props>>
- testType<Mutable<Readonly<Props>>>({
+ // @dts-jest:pass:snap -> AugmentedMutable<Readonly<Props>, "name" | "age" | "visible">
+ testType<AugmentedMutable<Readonly<Props>>>({
+ name: 'Yolo',
+ age: 99,
+ visible: true,
+ });
+
+ // @dts-jest:pass:snap -> AugmentedMutable<Readonly<Props>, "name" | "age">
+ testType<AugmentedMutable<Readonly<Props>, 'name' | 'age'>>({
  name: 'Yolo',
  age: 99,
  visible: true,
  });
 
  // @dts-jest:pass:snap -> string
- testType<Mutable<Readonly<Props>>['name']>('Yolo');
+ testType<AugmentedMutable<Readonly<Props>>['name']>('Yolo');
 
  // @dts-jest:pass:snap -> number
- testType<Mutable<Readonly<Props>>['age']>(99);
+ testType<AugmentedMutable<Readonly<Props>>['age']>(99);
 
  // @dts-jest:pass:snap -> boolean
- testType<Mutable<Readonly<Props>>['visible']>(true);
+ testType<AugmentedMutable<Readonly<Props>>['visible']>(true);
 }

src/mapped-types.spec.ts

@@ -40,7 +40,7 @@ import {
  ValuesType,
  AugmentedRequired,
  UnionToIntersection,
- Mutable,
+ AugmentedMutable,
 } from './mapped-types';
 
 /**
@@ -572,21 +572,28 @@ type RequiredOptionalProps = {
  testType<UnionToIntersection<'name' | 'age'>>();
 }
 
-// @dts-jest:group Mutable
+// @dts-jest:group AugmentedMutable
 {
  // @dts-jest:pass:snap
- testType<Mutable<Readonly<Props>>>({
+ testType<AugmentedMutable<Readonly<Props>>>({
  name: 'Yolo',
  age: 99,
  visible: true,
  });
 
  // @dts-jest:pass:snap
- testType<Mutable<Readonly<Props>>['name']>('Yolo');
+ testType<AugmentedMutable<Readonly<Props>, 'name' | 'age'>>({
+ name: 'Yolo',
+ age: 99,
+ visible: true,
+ });
+
+ // @dts-jest:pass:snap
+ testType<AugmentedMutable<Readonly<Props>>['name']>('Yolo');
 
  // @dts-jest:pass:snap
- testType<Mutable<Readonly<Props>>['age']>(99);
+ testType<AugmentedMutable<Readonly<Props>>['age']>(99);
 
  // @dts-jest:pass:snap
- testType<Mutable<Readonly<Props>>['visible']>(true);
+ testType<AugmentedMutable<Readonly<Props>>['visible']>(true);
 }

src/mapped-types.ts

@@ -632,9 +632,11 @@ export type UnionToIntersection<U> = (U extends any
  ? I
  : never;
 
+type Mutable<T> = { -readonly [P in keyof T]: T[P] };
+
 /**
  * Mutable
- * @desc From `T` make all properties become mutable
+ * @desc From `T`, make a set of properties, whose keys are in the union `K`, mutable
  * @example
  * type Props = {
  * readonly name: string;
@@ -644,6 +646,10 @@ export type UnionToIntersection<U> = (U extends any
  *
  * // Expect: { name: string; age: number; visible: boolean; }
  * Mutable<Props>;
+ *
+ * // Expect: { readonly name: string; age: number; visible: boolean; }
+ * Mutable<Props, 'age' | 'visible'>;
  */
-export type Mutable<T> = { -readonly [P in keyof T]: T[P] };
-export type Writable<T> = Mutable<T>;
+export type AugmentedMutable<T, K extends keyof T = keyof T> = Omit<T, K> &
+ Mutable<Pick<T, K>>;
+export type Writable<T, K extends keyof T = keyof T> = AugmentedMutable<T, K>;