Fixing types.

Author: mirek

package.json

@@ -31,13 +31,13 @@
     "@appliedblockchain/eslint-config": "3.0.0",
     "@tsconfig/node16": "1.0.2",
     "@types/jest": "27.4.1",
-    "@typescript-eslint/eslint-plugin": "5.12.1",
-    "@typescript-eslint/parser": "5.12.1",
-    "eslint": "8.9.0",
-    "eslint-plugin-jest": "26.1.1",
+    "@typescript-eslint/eslint-plugin": "5.17.0",
+    "@typescript-eslint/parser": "5.17.0",
+    "eslint": "8.12.0",
+    "eslint-plugin-jest": "26.1.3",
     "jest": "27.5.1",
     "npm-check": "5.9.2",
-    "ts-jest": "27.1.3",
-    "typescript": "4.5.5"
+    "ts-jest": "27.1.4",
+    "typescript": "4.6.3"
   }
 }

src/exact.ts

@@ -3,7 +3,7 @@ import { inspect } from 'util'
 import object from './object.js'
 
 const exact =
-  <T extends Record<string, Primitive | Assert<unknown>>>(kvs: T): Assert<{ [k in keyof T]: Asserted<T[k]> }> =>
+  <T extends Record<string, Primitive | Assert<unknown>>>(kvs: T): Assert<{ [k in keyof T]: T[k] extends Primitive ? T[k] : Asserted<T[k]> }> =>
     value => {
       if (typeof value !== 'object' || value === null) {
         throw new TypeError(`Expected object, got ${inspect(value)}.`)
@@ -15,7 +15,7 @@ const exact =
       if (keys.length) {
         throw new TypeError(`Unexpected extra keys ${keys.map(String).join(', ')} in ${inspect(value)}.`)
       }
-      return result as { [k in keyof T]: Asserted<T[k]> }
+      return result as { [k in keyof T]: T[k] extends Primitive ? T[k] : Asserted<T[k]> }
     }
 
 export default exact

src/object.test.ts

@@ -1,5 +1,20 @@
 import * as $ from './index.js'
 
+export type My = {
+  id: number,
+  uuid: string,
+  reason: null | string
+}
+
+export const assert: $.Assert<My> =
+  $.object({
+    id: $.number,
+    uuid: $.string,
+    reason: $.nullOr($.string)
+  })
+
+export type My2 = $.Asserted<typeof assert>
+
 test('object', () => {
   const r = $.object({ foo: $.string, bar: $.number })(JSON.parse('{"foo":"a","bar":1}'))
   expect(r).toEqual({ foo: 'a', bar: 1 })

src/object.ts

@@ -2,7 +2,7 @@ import { inspect } from 'util'
 import type { Assert, Asserted, Primitive } from './prelude.js'
 
 const object =
-  <T extends Record<string, Primitive | Assert<unknown>>>(kvs: T): Assert<{ [k in keyof T]: Asserted<T[k]> }> =>
+  <T extends Record<string, Assert<unknown> | Primitive>>(kvs: T): Assert<{ [k in keyof T]: T[k] extends Primitive ? T[k] : Asserted<T[k]> }> =>
     value => {
       if (typeof value !== 'object' || value === null) {
         throw new TypeError(`Expected object, got ${inspect(value)}.`)
@@ -19,7 +19,7 @@ const object =
           throw new TypeError(`Expected ${inspect(k)} to be ${inspect(v)}, got ${inspect((value as Record<string, unknown>)[k])} in ${inspect(value)} object.`)
         }
       }
-      return value as { [k in keyof T]: Asserted<T[k]> }
+      return value as { [k in keyof T]: T[k] extends Primitive ? T[k] : Asserted<T[k]> }
     }
 
 export default object

src/partial.ts

@@ -2,7 +2,7 @@ import { inspect } from 'util'
 import type { Assert, Asserted, Primitive } from './prelude.js'
 
 const partial =
-  <T extends Record<string, Primitive | Assert<unknown>>>(kvs: T): Assert<{ [k in keyof T]?: Asserted<T[k]> }> =>
+  <T extends Record<string, Primitive | Assert<unknown>>>(kvs: T): Assert<{ [k in keyof T]?: T[k] extends Primitive ? T[k] : Asserted<T[k]> }> =>
     value => {
       if (typeof value !== 'object' || value == null) {
         throw new TypeError('Expected object.')

src/prelude.ts

@@ -10,9 +10,7 @@ export type Assert<R> =
 export type Asserted<A> =
   A extends (value: unknown) => infer U ?
     U :
-    A extends Primitive ?
-      A :
-      never
+    never
 
 export type Awaited<T> =
   T extends PromiseLike<infer U> ?