feat: add entries function

fixes #547

docs/functions.md

@@ -86,23 +86,23 @@ filter $ => .age >= 18
 Returns the length of the input:
 
 ```
-[1, 0, 1] | length;
+[1, 0, 1] | length
 ```
 
 ```
-3;
+3
 ```
 
 ## reverse
 
 Reverses the input:
 
 ```
-[1, 2, 3] | reverse;
+[1, 2, 3] | reverse
 ```
 
 ```
-[3, 2, 1];
+[3, 2, 1]
 ```
 
 ## reduce \
@@ -121,7 +121,7 @@ Returns the keys of an object:
 ```
 
 ```
-['foo', 'baz'];
+['foo', 'baz']
 ```
 
 ## values
@@ -133,7 +133,19 @@ Returns the values of an object:
 ```
 
 ```
-['bar', 42];
+['bar', 42]
+```
+
+## entries
+
+Returns the entries of an object as an array of arrays:
+
+```
+{"foo": "bar", "baz": 42} | entries
+```
+
+```
+[["foo", "bar"], ["baz", 42]]
 ```
 
 ## combinations
@@ -145,17 +157,17 @@ Returns all combinations of each possible choice of r elements of the input:
 ```
 
 ```
-[['A', 'B'], ['A', 'C'], ['A', 'D'], ['B', 'C'], ['B', 'D'], ['C', 'D']];
+[['A', 'B'], ['A', 'C'], ['A', 'D'], ['B', 'C'], ['B', 'D'], ['C', 'D']]
 ```
 
 ## product
 
 Computes the product of the iterables in the input:
 
 ```
-[['a', 'b'], ['1', '2']] | product;
+[['a', 'b'], ['1', '2']] | product
 ```
 
 ```
-[['a', '1'], ['a', '2'], ['b', '1'], ['b', '2']];
+[['a', '1'], ['a', '2'], ['b', '1'], ['b', '2']]
 ```

src/__tests__/builtins.test.js

@@ -14,6 +14,7 @@ const {
   keys,
   split,
   values,
+  entries,
   combinations,
   product,
   __opt__,
@@ -310,6 +311,15 @@ describe('built ins', () => {
     })
   })
 
+  describe('entries', () => {
+    it('returns correct value', () => {
+      expect(entries({})).toEqual([])
+      expect(new Set(entries({ foo: 'bar', baz: 4 }))).toEqual(
+        new Set([['foo', 'bar'], ['baz', 4]])
+      )
+    })
+  })
+
   describe('sortBy', () => {
     it('returns correct value', () => {
       const id = a => a // eslint-disable-line

src/builtins.js

@@ -167,6 +167,8 @@ export default {
   keys: (input: { [string]: mixed }): Array<string> => Object.keys(input),
 
   values: (input: { [string]: mixed }): Array<mixed> => Object.values(input),
+  entries: (input: { [string]: mixed }): Array<[string, mixed]> =>
+    Object.entries(input),
 
   combinations: (r: number): Array<mixed> | (string => Array<Array<mixed>>) => (
     input: Array<mixed> | string