Add mixed type (#81)

* Add mixed type

* Add mixed to TOC

* Add mixed test

* Run Prettier

* Update snapshots

* Update mixed description

* Add link for mixed docs

* Move mixed to Utility types section

* Add missing spaces

README.md

@@ -119,6 +119,7 @@ Issues can be funded by anyone and the money will be transparently distributed t
 * [`$Shape<T>`](#shapet)
 * [`$NonMaybeType<T>`](#nonmaybetypet)
 * [`Class<T>`](#classt)
+* [`mixed`](#mixed)
 
 ## Deprecated API (use at own risk)
 * `getReturnOfExpression()` - from TS v2.0 it's better to use type-level `ReturnType` instead
@@ -949,6 +950,13 @@ function makeStore(storeClass: Class<Store>): Store {
 
 [⇧ back to top](#flows-utility-types)
 
+### mixed
+
+An arbitrary type that could be anything (same as `unknown`)  
+https://flow.org/en/docs/types/mixed
+
+[⇧ back to top](#table-of-contents)
+
 ---
 
 MIT License

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

@@ -35,3 +35,5 @@ exports[`$Shape testType<$Shape<Props>>() 1`] = `"Partial<Props>"`;
 exports[`$Values testType<$Values<Props>>() 1`] = `"string | number | boolean"`;
 
 exports[`Class testType<Class<Foo>>() 1`] = `"Class<Foo>"`;
+
+exports[`mixed testType<mixed>() 1`] = `"unknown"`;

src/utility-types.spec.snap.ts

@@ -10,6 +10,7 @@ import {
   $Shape,
   $NonMaybeType,
   Class,
+  mixed,
 } from './utility-types';
 import { _DeepReadonlyObject } from './mapped-types';
 /**
@@ -113,3 +114,9 @@ it('Class', () => {
   // @dts-jest:pass:snap -> Class<Foo>
   testType<Class<Foo>>();
 });
+
+// @dts-jest:group mixed
+it('mixed', () => {
+  // @dts-jest:pass:snap -> unknown
+  testType<mixed>();
+});

src/utility-types.spec.ts

@@ -10,6 +10,7 @@ import {
   $Shape,
   $NonMaybeType,
   Class,
+  mixed,
 } from './utility-types';
 import { _DeepReadonlyObject } from './mapped-types';
 /**
@@ -113,3 +114,9 @@ it('Class', () => {
   // @dts-jest:pass:snap
   testType<Class<Foo>>();
 });
+
+// @dts-jest:group mixed
+it('mixed', () => {
+  // @dts-jest:pass:snap
+  testType<mixed>();
+});

src/utility-types.ts

@@ -156,3 +156,20 @@ export type $NonMaybeType<T> = NonNullable<T>;
  *   }
  */
 export type Class<T> = new (...args: any[]) => T;
+
+/**
+ * mixed
+ * @desc An arbitrary type that could be anything
+ * @see https://flow.org/en/docs/types/mixed
+ * @example
+ *
+ * function stringify(value: mixed) {
+ *     // ...
+ *   }
+ *
+ *   stringify("foo");
+ *   stringify(3.14);
+ *   stringify(null);
+ *   stringify({});
+ */
+export type mixed = unknown;