descend

files/index.d.ts

@@ -5340,6 +5340,7 @@ Notes: TS typings are oversimplified
 */
 // @SINGLE_MARKER
 export function addIndex(originalFn: any): (fn: any) => (list: any[]) => any[];
+export function addIndex(originalFn: any): (fn: any, list: any[]) => any[];
 
 /*
 Method: ap
@@ -5378,6 +5379,7 @@ Notes: TS typings are oversimplified
 */
 // @SINGLE_MARKER
 export function addIndexRight(originalFn: any): (fn: any) => (list: any[]) => any[];
+export function addIndexRight(originalFn: any): (fn: any, list: any[]) => any[];
 
 /*
 Method: aperture
@@ -5437,6 +5439,25 @@ Notes:
 export function ascend<T>(fn: (obj: T) => Ord, a: T, b: T): Ordering;
 export function ascend<T>(fn: (obj: T) => Ord): (a: T, b: T) => Ordering;
 
+/*
+Method: descend
+
+Explanation:
+
+Example:
+
+```
+```
+
+Categories:
+
+Notes:
+
+*/
+// @SINGLE_MARKER
+export function descend<T>(fn: (obj: T) => Ord, a: T, b: T): Ordering;
+export function descend<T>(fn: (obj: T) => Ord): (a: T, b: T) => Ordering;
+
 // RAMBDAX_MARKER_START
 
 /*

source/ascend.js

@@ -2,10 +2,8 @@ export function createCompareFunction(
   a, b, winner, loser
 ){
   if (a === b) return 0
-  if (a == null) return winner
-  if (a == null) return loser
 
-  return a > b ? loser : winner
+  return a < b ? winner : loser
 }
 
 export function ascend(

source/ascend.spec.js

@@ -1,13 +1,12 @@
 import { ascend } from './ascend.js'
-import { descend } from './ascend.js'
+import { descend } from './descend.js'
 import { sort } from './sort.js'
 
 const people = [
   {
     name : 'Emma',
     age  : 70,
   },
-  {name: 'noage'},
   {
     name : 'Peter',
     age  : 78,
@@ -19,7 +18,7 @@ const people = [
 ]
 
 test('ascend', () => {
-  const result = sort(ascend(x => x.age),
+  const result = sort(ascend(x => x?.age),
     people)
   const expected = [
     {
@@ -37,3 +36,24 @@ test('ascend', () => {
   ]
   expect(result).toEqual(expected)
 })
+
+test('descend', () => {
+  const result = sort(descend(x => x?.age),
+    people)
+  const expected = [
+    {
+      name : 'Peter',
+      age  : 78,
+    },
+    {
+      name : 'Emma',
+      age  : 70,
+    },
+    {
+      name : 'Mikhail',
+      age  : 62,
+    },
+  ]
+
+  expect(result).toEqual(expected)
+})

source/descend.js

@@ -0,0 +1,17 @@
+import { createCompareFunction } from './ascend.js'
+
+export function descend(
+  getFunction, a, b
+){
+  if (arguments.length === 1){
+    return (_a, _b) => descend(
+      getFunction, _a, _b
+    )
+  }
+  const aValue = getFunction(a)
+  const bValue = getFunction(b)
+
+  return createCompareFunction(
+    aValue, bValue, 1, -1
+  )
+}