feat: create lens module

BREAKING CHANGE: get and set functions were moved into lens module

src/index.ts

@@ -1,5 +1,3 @@
-export { default as get } from './get'
-export { default as set } from './set'
 export { default as tap } from './tap'
 export { default as pipe } from './pipe'
 export { default as apply } from './apply'

src/get.ts → src/lens/get.ts

@@ -1,9 +1,9 @@
 /**
- * @module Get
+ * @module Lens
  */
 
-import permutation2 from './permutation/permutation-2'
-import type { Flatten, Flattenable } from './types/flatten'
+import permutation2 from '../permutation/permutation-2'
+import type { Flatten, Flattenable } from '../types/flatten'
 
 /**
  * Gets the value type inside a nested object type `Source` by provided `Path`
@@ -16,15 +16,16 @@ export type Get<
   Source extends Record<string, unknown>
     ? Path extends `${number}.${infer Right}`
       ? Get<Source, Right>
+      // @ts-ignore
       : Path extends `${infer Left extends keyof Source}.${infer Right}`
         // @ts-ignore
         ? Get<Exclude<Source[Left], undefined>, Right> | Extract<Source[Left], undefined>
         : Path extends keyof Source
           ? Source[Path]
           : never
     : Source extends any[]
-      ? Path extends `${infer Left extends number}.${infer Right}`
-        ? Get<Exclude<Source[Left], undefined>, Right> | Extract<Source[Left], undefined>
+      ? Path extends `${infer Index extends number}.${infer Right}`
+        ? Get<Exclude<Source[Index], undefined>, Right> | Extract<Source[Index], undefined>
         : Path extends `${infer Index extends number}`
           ? Source[Index]
           : never
@@ -34,30 +35,35 @@ export type Get<
  * Gets the value inside a nested `source` object by provided `path`
  * written in dot-notation.
  */
+// @ts-ignore
 export default function get<
   Source extends Flattenable,
   Path extends Flatten<Source>
 > (
   path: Path
+  // @ts-ignore
 ): (source: Source) => Get<Source, Path>
 
 /**
  * Gets the value inside a nested `source` object by provided `path`
  * written in dot-notation.
  */
+// @ts-ignore
 export default function get<
   Source extends Flattenable,
   Path extends Flatten<Source>
 > (
   source: Source,
   path: Path
+  // @ts-ignore
 ): Get<Source, Path>
 
 /**
  * Gets the value inside a nested `source` object by provided `path`
  * written in dot-notation.
  */
 export default function get (...args: [any, any?]): any {
+  // @ts-ignore
   return permutation2(
     <
       Source extends Flattenable,

src/lens/index.ts

@@ -0,0 +1,2 @@
+export { default as set } from './set'
+export { default as get } from './get'

src/lens/set.ts

@@ -0,0 +1,117 @@
+/**
+ * @module Lens
+ */
+
+import type { Unshift } from '../types/unshift'
+import permutation3 from '../permutation/permutation-3'
+import type { Flatten, Flattenable } from '../types/flatten'
+
+/**
+ * Sets the `Value` type inside a nested object type `Source` by provided `Path`
+ * written in dot-notation.
+ */
+export type Set<
+  Source extends Flattenable,
+  Path extends string,
+  Value
+> =
+  Source extends Record<string, unknown>
+    ? Path extends `${number}.${infer Right}`
+      ? Set<Source, Right, Value>
+      // @ts-ignore
+      : Path extends `${infer Left extends keyof Source}.${infer Right}`
+        ? {
+          [Key in keyof Source]: Key extends Exclude<keyof Source, Left>
+            ? Source[Key]
+            // @ts-ignore
+            : Set<Exclude<Source[Left], undefined>, Right, Value>
+        }
+        : Path extends keyof Source
+          ? {
+            [Key in keyof Source]: Key extends Exclude<keyof Source, Path>
+              ? Source[Key]
+              : Value
+          }
+          : never
+    : Source extends any[]
+      ? Path extends `${infer Index extends number}.${infer Right}`
+        ? Unshift<Source, Index, Set<Exclude<Source[Index], undefined>, Right, Value>>
+        : Path extends `${infer Index extends number}`
+          ? Unshift<Source, Index, Value>
+          : never
+      : never
+
+/**
+ * Sets the `value` inside a nested `source` object by provided `path`
+ * written in dot-notation.
+ */
+// @ts-ignore
+export default function set<
+  Source extends Flattenable,
+  Path extends Flatten<Source>,
+  Value
+> (
+  path: Path,
+  value: Value,
+  // @ts-ignore
+): (source: Source) => Set<Source, Path, Value>
+
+/**
+ * Sets the `value` inside a nested `source` object by provided `path`
+ * written in dot-notation.
+ */
+// @ts-ignore
+export default function set<
+  Source extends Flattenable,
+  Path extends Flatten<Source>,
+  Value
+> (
+  source: Source,
+  path: Path,
+  value: Value
+  // @ts-ignore
+): Set<Source, Path, Value>
+
+/**
+ * Sets the `value` inside a nested `source` object by provided `path`
+ * written in dot-notation.
+ */
+export default function set (...args: [any, any, any?]): any {
+  // @ts-ignore
+  return permutation3(
+    // @ts-ignore
+    <
+      Source extends Flattenable,
+      Path extends Flatten<Source>,
+      Value
+    >(
+      source: Source,
+      path: Path,
+      value: Value
+      // @ts-ignore
+    ): Set<Source, Path, Value> => {
+      // @ts-ignore
+      const keys = path.split('.')
+      const length = keys.length
+
+      let result = structuredClone(source)
+
+      if (length === 0) {
+        result[path as keyof Source] = value as Source[keyof Source]
+      }
+
+      let scope: any = result[keys[0]! as keyof Source]
+
+      for (let index = 1; index < length; index += 1) {
+        if (index === length - 1) {
+          scope[keys?.[index] as keyof typeof scope] = value
+        } else {
+          scope = scope?.[keys?.[index] as keyof typeof scope]
+        }
+      }
+
+      // @ts-ignore
+      return result as Set<Source, Path, Value>
+    }
+  )(...args)
+}

tests/get.spec.ts

@@ -1,4 +1,4 @@
-import sut from '../src/get'
+import sut from '../src/lens/get'
 
 describe('get', () => {
   describe('when accessing a property', () => {

tests/guard.spec.ts

@@ -4,8 +4,8 @@ describe('guard', () => {
   describe('when encountering a truthy guard', () => {
     it('should execute the function next to that guard', () => {
       expect(
-        sut<(x: number) => number>(
-          [(x) => x < 5, (x) => x + 1],
+        sut(
+          [(x) => x < 5, (x: number) => x + 1],
           [(x) => x === 5, (x) => x - 1],
           () => 1
         )(5)
@@ -15,21 +15,21 @@ describe('guard', () => {
     it('should not check further guards', () => {
       const guardNotToBeCalled = jest.fn((x: number) => x < 5)
 
-      sut<(x: number) => number>(
-        [(x) => x === 5, (x) => x - 1],
+      sut(
+        [(x) => x === 5, (x: number) => x - 1],
         [guardNotToBeCalled, (x) => x + 1],
         () => 1
       )(5)
 
-      expect(guardNotToBeCalled).not.toBeCalled()
+      expect(guardNotToBeCalled).not.toHaveBeenCalled()
     })
   })
 
   describe('when no truthy guards are present', () => {
     it('should execute the default function', () => {
       expect(
-        sut<(x: number) => number>(
-          [(x) => x < 5, (x) => x + 1],
+        sut(
+          [(x) => x < 5, (x: number) => x + 1],
           [(x) => x > 5, (x) => x - 1],
           () => 1
         )(5)

tests/set.spec.ts

@@ -0,0 +1,33 @@
+import sut from '../src/lens/set'
+
+describe('set', () => {
+  describe('when setting a property', () => {
+    it('should return source copy with modified value', () => {
+      const source = { a: { b: { c: 1 } } }
+      const result = sut(source, 'a.b.c', 2)
+
+      expect(result).toEqual({ a: { b: { c: 2 } } })
+      expect(source === result).toBe(false)
+    })
+  })
+
+  describe('when setting a nested array\'s element', () => {
+    it('should return source copy with modified value', () => {
+      const source = { a: { b: { c: [1] } } }
+      const result = sut(source, 'a.b.c.0', 2)
+
+      expect(result).toEqual({ a: { b: { c: [2] } } })
+      expect(source === result).toBe(false)
+    })
+
+    describe('when an element is object', () => {
+      it('should return source copy with modified value', () => {
+        const source = { a: { b: { c: [{ a: { b: 2 } }] } } }
+        const result = sut(source, 'a.b.c.0.a.b', 3)
+
+        expect(result).toEqual({ a: { b: { c: [{ a: { b: 3 } }] } } })
+        expect(source === result).toBe(false)
+      })
+    })
+  })
+})

typetests/get.test.ts

@@ -1,4 +1,4 @@
-import get from '../src/get'
+import get from '../src/lens/get'
 
 import tacit from './tacit'
 

typetests/pipe.test.ts

@@ -72,7 +72,7 @@ const a8: Maybe<boolean> = tacit(
         (value) => `${value}` === '1',
       ),
       pipe(
-        identity,
+        (value) => Number(value),
         (value: number): string => `${value}`,
       ),
     ),

typetests/set.test.ts

@@ -0,0 +1,84 @@
+import set from '../src/lens/set'
+
+import tacit from './tacit'
+
+const source = {
+  a: 1,
+  b: {
+    c: true,
+    d: {
+      e: [
+        {
+          f: ''
+        }
+      ],
+      g: [
+        3
+      ]
+    }
+  }
+}
+
+// region full
+
+const a1: typeof source = set(
+  source,
+  'a',
+  2
+)
+
+const a2: typeof source = set(
+  source,
+  'b.c',
+  false
+)
+
+const a3: typeof source = set(
+  source,
+  'b.d.e.0.f',
+  'f'
+)
+
+const a4: typeof source = set(
+  source,
+  'b.d.g',
+  [2]
+)
+
+// endregion
+
+// region tacit
+
+const b1: typeof source = tacit(
+  set(
+    'a',
+    2
+  ),
+  source
+)
+
+const b2: typeof source = tacit(
+  set(
+    'b.c',
+    false
+  ),
+  source
+)
+
+const b3: typeof source = tacit(
+  set(
+    'b.d.e.0.f',
+    'f'
+  ),
+  source
+)
+
+const b4: typeof source = tacit(
+  set(
+    'b.d.g',
+    [2]
+  ),
+  source
+)
+
+// endregion