Add object.prop function

docs/modules/struct.ts.md

@@ -16,6 +16,7 @@ Added in v2.10.0
   - [getAssignSemigroup](#getassignsemigroup)
 - [utils](#utils)
   - [evolve](#evolve)
+  - [prop](#prop)
 
 ---
 
@@ -80,3 +81,35 @@ assert.deepStrictEqual(
 ```
 
 Added in v2.11.0
+
+## prop
+
+Accesses a property of an object
+
+**Signature**
+
+```ts
+export declare const prop: <Path extends keyof A extends never ? string : keyof A, A>(
+  path: Path
+) => <B extends { [k in Path]: unknown }>(
+  obj: keyof A extends never ? B : A
+) => Path extends keyof A ? A[Path] : B[Path]
+```
+
+**Example**
+
+```ts
+import { pipe } from 'fp-ts/function'
+import { prop } from 'fp-ts/struct'
+
+type Person = {
+  readonly name: string
+  readonly age: number
+}
+
+const person: Person = { name: 'Jane', age: 62 }
+assert.deepStrictEqual(prop('name')(person), 'Jane')
+assert.deepStrictEqual(pipe(person, prop('age')), 62)
+```
+
+Added in v2.11.0

src/struct.ts

@@ -63,3 +63,27 @@ export const evolve = <A, F extends { [K in keyof A]: (a: A[K]) => unknown }>(tr
   }
   return out as any
 }
+
+/**
+ * Accesses a property of an object
+ *
+ * @example
+ * import { pipe } from 'fp-ts/function'
+ * import { prop } from 'fp-ts/struct'
+ *
+ * type Person = {
+ *   readonly name: string
+ *   readonly age: number
+ * }
+ *
+ * const person: Person = { name: 'Jane', age: 62 }
+ * assert.deepStrictEqual(prop('name')(person), 'Jane')
+ * assert.deepStrictEqual(pipe(person, prop('age')), 62)
+ *
+ * @since 2.11.0
+ */
+export const prop = <Path extends keyof A extends never ? string : keyof A, A>(path: Path) => <
+  B extends { [k in Path]: unknown }
+>(
+  obj: keyof A extends never ? B : A
+) => (obj as B)[path] as Path extends keyof A ? A[Path] : B[Path]

test/struct.ts

@@ -36,4 +36,15 @@ describe('struct', () => {
     x.b = 1
     U.deepStrictEqual(pipe(x, _.evolve({ b: (b) => b > 0 })), { b: true })
   })
+
+  it('prop', () => {
+    interface Person {
+      readonly name: string
+      readonly age: number
+    }
+
+    const person: Person = { name: 'Jane', age: 62 }
+    U.deepStrictEqual(_.prop('name')(person), 'Jane')
+    U.deepStrictEqual(pipe(person, _.prop('age')), 62)
+  })
 })