mixedArray and mixedDict now return readonly (upgrade Flow)

See these Flow issues for explanation:

- facebook/flow#7684
- facebook/flow#7685

This is a breaking change.

Fixes #3.

README.md

@@ -650,7 +650,7 @@ const personDecoder: (mixed) => Person = record({
 
 #### `mixedArray`
 
-`(value: mixed) => Array<mixed>`
+`(value: mixed) => $ReadOnlyArray<mixed>`
 
 Usually you want to use [array] instead. `array` actually uses this decoder
 behind the scenes, to verify that `value` is an array (before proceeding to
@@ -663,7 +663,7 @@ undefined, null and missing values][example-missing-values].
 
 #### `mixedDict`
 
-`(value: mixed) => { [string]: mixed }`
+`(value: mixed) => { +[string]: mixed }`
 
 Usually you want to use [dict] or [record] instead. `dict` and `record` actually
 use this decoder behind the scenes, to verify that `value` is an object (before

flow/rename.js

@@ -36,11 +36,11 @@ verifyCamel(
 verifyCamel(
   // $ExpectError
   map(
-    // $ExpectError
     record({
       first_name: string,
       age: number,
     }),
+    // $ExpectError
     ({ fist_name: firstName, ...rest }) => ({ firstName, ...rest })
   )
 );

package.json

@@ -52,7 +52,7 @@
     "eslint-plugin-jest": "22.6.4",
     "eslint-plugin-prettier": "3.1.0",
     "eslint-plugin-simple-import-sort": "3.1.1",
-    "flow-bin": "0.95.1",
+    "flow-bin": "0.100.0",
     "jest": "24.8.0",
     "npm-run-all": "4.1.5",
     "prettier": "1.18.0",

src/index.js

@@ -21,14 +21,14 @@ export function string(value: mixed): string {
   return value;
 }
 
-export function mixedArray(value: mixed): Array<mixed> {
+export function mixedArray(value: mixed): $ReadOnlyArray<mixed> {
   if (!Array.isArray(value)) {
     throw new TypeError(`Expected an array, but got: ${repr(value)}`);
   }
   return value;
 }
 
-export function mixedDict(value: mixed): { [string]: mixed } {
+export function mixedDict(value: mixed): { +[string]: mixed } {
   if (typeof value !== "object" || value == null || Array.isArray(value)) {
     throw new TypeError(`Expected an object, but got: ${repr(value)}`);
   }

typescript/decoders.ts

@@ -26,9 +26,9 @@ boolean(undefined);
 number(undefined);
 // $ExpectType string
 string(undefined);
-// $ExpectType unknown[]
+// $ExpectType readonly unknown[]
 mixedArray(undefined);
-// $ExpectType { [key: string]: unknown; }
+// $ExpectType { readonly [key: string]: unknown; }
 mixedDict(undefined);
 // $ExpectType true
 constant(true)(undefined);
@@ -88,7 +88,7 @@ fieldAndThen("", string, () => string)(undefined);
 fieldAndThen(0, string, () => string)(undefined);
 // $ExpectType string | number
 either(string, number)(undefined);
-// $ExpectType string | number | boolean | { [key: string]: unknown; }
+// $ExpectType string | number | boolean | { readonly [key: string]: unknown; }
 either(either(boolean, string), either(number, mixedDict))(undefined);
 // $ExpectType string
 lazy(() => string)(undefined);

typescript/index.d.ts

@@ -8,9 +8,9 @@ export function number(value: unknown): number;
 
 export function string(value: unknown): string;
 
-export function mixedArray(value: unknown): Array<unknown>;
+export function mixedArray(value: unknown): ReadonlyArray<unknown>;
 
-export function mixedDict(value: unknown): { [key: string]: unknown };
+export function mixedDict(value: unknown): { readonly [key: string]: unknown };
 
 export function constant<
   T extends boolean | number | string | undefined | null