make Record.hasOwnProperty a type guard

docs/modules/Record.ts.md

@@ -353,14 +353,14 @@ Added in v2.0.0
 **Signature**
 
 ```ts
-export function hasOwnProperty<K extends string>(k: K, r: Record<K, unknown>): boolean { ... }
+export function hasOwnProperty<K extends string>(k: string, r: Record<K, unknown>): k is K { ... }
 ```
 
 Added in v2.0.0
 
 # insertAt (function)
 
-Insert or replace a key/value pair in a map
+Insert or replace a key/value pair in a record
 
 **Signature**
 
@@ -445,7 +445,7 @@ Added in v2.0.0
 **Signature**
 
 ```ts
-export function modifyAt<K extends string, A>(k: K, f: (a: A) => A): (r: Record<K, A>) => Option<Record<K, A>> { ... }
+export function modifyAt<A>(k: string, f: (a: A) => A): <K extends string>(r: Record<K, A>) => Option<Record<K, A>> { ... }
 ```
 
 Added in v2.0.0
@@ -648,7 +648,7 @@ Added in v2.0.0
 **Signature**
 
 ```ts
-export function updateAt<K extends string, A>(k: K, a: A): (r: Record<K, A>) => Option<Record<K, A>> { ... }
+export function updateAt<A>(k: string, a: A): <K extends string>(r: Record<K, A>) => Option<Record<K, A>> { ... }
 ```
 
 Added in v2.0.0

dtslint/ts3.5/Record.ts

@@ -0,0 +1,39 @@
+import { pipe } from '../../src/pipeable'
+import * as R from '../../src/Record'
+import { identity } from '../../src/function'
+
+declare const dictionaryString: { [key: string]: number }
+declare const recordString: Record<string, number>
+declare const recordStringEnum: Record<'a' | 'b', number>
+
+declare const keyString: string
+
+//
+// hasOwnProperty
+//
+
+if (R.hasOwnProperty(keyString, dictionaryString)) {
+  keyString // $ExpectType string
+}
+if (R.hasOwnProperty(keyString, recordString)) {
+  keyString // $ExpectType string
+}
+if (R.hasOwnProperty(keyString, recordStringEnum)) {
+  keyString // $ExpectType "a" | "b"
+}
+
+//
+// updateAt
+//
+
+pipe(dictionaryString, R.updateAt('a', 3)) // $ExpectType Option<Record<string, number>>
+pipe(recordString, R.updateAt('a', 3)) // $ExpectType Option<Record<string, number>>
+pipe(recordStringEnum, R.updateAt('a', 3)) // $ExpectType Option<Record<"a" | "b", number>>
+
+//
+// modifyAt
+//
+
+pipe(dictionaryString, R.modifyAt('a', identity)) // $ExpectType Option<Record<string, number>>
+pipe(recordString, R.modifyAt('a', identity)) // $ExpectType Option<Record<string, number>>
+pipe(recordStringEnum, R.modifyAt('a', identity)) // $ExpectType Option<Record<"a" | "b", number>>

src/Record.ts

@@ -123,7 +123,7 @@ export function toUnfoldable<F>(unfoldable: Unfoldable<F>): <A>(r: Record<string
 }
 
 /**
- * Insert or replace a key/value pair in a map
+ * Insert or replace a key/value pair in a record
  *
  * @since 2.0.0
  */
@@ -144,7 +144,7 @@ const _hasOwnProperty = Object.prototype.hasOwnProperty
 /**
  * @since 2.0.0
  */
-export function hasOwnProperty<K extends string>(k: K, r: Record<K, unknown>): boolean {
+export function hasOwnProperty<K extends string>(k: string, r: Record<K, unknown>): k is K {
   return _hasOwnProperty.call(r, k)
 }
 
@@ -170,7 +170,7 @@ export function deleteAt(k: string): <A>(r: Record<string, A>) => Record<string,
 /**
  * @since 2.0.0
  */
-export function updateAt<K extends string, A>(k: K, a: A): (r: Record<K, A>) => Option<Record<K, A>> {
+export function updateAt<A>(k: string, a: A): <K extends string>(r: Record<K, A>) => Option<Record<K, A>> {
   return r => {
     if (!hasOwnProperty(k, r)) {
       return none
@@ -187,7 +187,7 @@ export function updateAt<K extends string, A>(k: K, a: A): (r: Record<K, A>) =>
 /**
  * @since 2.0.0
  */
-export function modifyAt<K extends string, A>(k: K, f: (a: A) => A): (r: Record<K, A>) => Option<Record<K, A>> {
+export function modifyAt<A>(k: string, f: (a: A) => A): <K extends string>(r: Record<K, A>) => Option<Record<K, A>> {
   return r => {
     if (!hasOwnProperty(k, r)) {
       return none