feat(append): Add module append

src/__tests__/append.js

@@ -0,0 +1,6 @@
+import append from '../append';
+
+test('Core.append', () => {
+  expect(append('c', ['a', 'b'])).toEqual(['a', 'b', 'c']);
+  expect(append(['c'], ['a', 'b'])).toEqual(['a', 'b', ['c']]);
+});

src/append.js

@@ -0,0 +1,3 @@
+import concat from './concat';
+
+export default (el, list) => concat(list, [el]);

src/filter.js

@@ -1,4 +1,5 @@
 import reduce from './reduce';
+import append from './append';
 
 export default (fn, arr) =>
-  reduce((a, e) => (fn(e) ? a.concat(e) : a), [], arr);
+  reduce((a, e) => (fn(e) ? append(e, a) : a), [], arr);

src/index.js

@@ -1,5 +1,6 @@
 import allPass from './allPass';
 import anyPass from './anyPass';
+import append from './append';
 import compose from './compose';
 import concat from './concat';
 import curry from './curry';
@@ -21,6 +22,7 @@ import slice from './slice';
 export {
   allPass,
   anyPass,
+  append,
   compose,
   concat,
   curry,

src/reverse.js

@@ -1,9 +1,10 @@
 import reduceRight from './reduceRight';
 import pipe from './pipe';
 import isArray from './isArray';
+import append from './append';
 
 export default arr => {
-  const reverseArray = list => reduceRight((a, e) => a.concat(e), [], list);
+  const reverseArray = list => reduceRight((a, e) => append(e, a), [], list);
   const reverseString = pipe(s => s.split(''), reverseArray, a => a.join(''));
 
   if (isArray(arr)) return reverseArray(arr);