allow arrays into the arithmetic macros

README.md

@@ -502,7 +502,7 @@ source1: 3,
 source2: 2,
 source3: 1,
 value1: difference('source1', 'source2', 'source3'), // 0
-value2: difference('source1', difference('source2', 'source3')) // 2
+value2: difference('source1', collect('source2', 'source3')) // 2
 ```
 
 ##### `divide`
@@ -706,7 +706,7 @@ source1: 1,
 source2: 2,
 source3: 3,
 value1: product('source1', 'source2', 'source3'), // 6
-value2: product('source1', product('source2', 'source3')) // 6
+value2: product('source1', collect('source2', 'source3')) // 6
 ```
 
 ##### `promise.all`
@@ -804,7 +804,7 @@ source1: 3,
 source2: 2,
 source3: 1,
 value1: quotient('source1', 'source2', 'source3'), // 1.5
-value2: quotient('source1', quotient('source2', 'source3')) // 1.5
+value2: quotient('source1', collect('source2', 'source3')) // 1.5
 ```
 
 ##### `string.camelize`
@@ -989,7 +989,7 @@ source1: 1,
 source2: 2,
 source3: 3,
 value1: sum('source1', 'source2', 'source3'), // 6
-value2: sum('source1', sum('source2', 'source3')) // 6
+value2: sum('source1', collect('source2', 'source3')) // 6
 ```
 
 ##### `tag`

addon/-utils.js

@@ -3,7 +3,22 @@ import lazyCurriedComputed from 'ember-macro-helpers/lazy-curried-computed';
 
 export function reduceKeys(func) {
   return curriedComputed((...values) => {
-    return values.reduce(func);
+    if (values.length === 0) {
+      return 0;
+    }
+    return values.reduce((total, next, i) => {
+      if (Array.isArray(next)) {
+        if (next.length === 0) {
+          next = 0;
+        } else {
+          next = next.reduce(func);
+        }
+      }
+      if (i === 0) {
+        return next;
+      }
+      return func(total, next);
+    }, null);
   });
 }
 

tests/integration/add-test.js

@@ -1,5 +1,6 @@
 import { add } from 'ember-awesome-macros';
 import { module, test } from 'qunit';
+import { A as emberA } from 'ember-array/utils';
 import compute from 'ember-macro-test-helpers/compute';
 
 module('Integration | Macro | add');
@@ -29,6 +30,22 @@ test('adds three numbers', function(assert) {
   });
 });
 
+test('allows empty arrays', function(assert) {
+  compute({
+    assert,
+    computed: add(emberA()),
+    strictEqual: 0
+  });
+});
+
+test('adds array members', function(assert) {
+  compute({
+    assert,
+    computed: add(emberA([1, 2]), emberA([3])),
+    strictEqual: 6
+  });
+});
+
 test('handles all undefined', function(assert) {
   compute({
     assert,

tests/integration/divide-test.js

@@ -1,5 +1,6 @@
 import { divide } from 'ember-awesome-macros';
 import { module, test } from 'qunit';
+import { A as emberA } from 'ember-array/utils';
 import compute from 'ember-macro-test-helpers/compute';
 
 module('Integration | Macro | divide');
@@ -29,6 +30,22 @@ test('divides three numbers', function(assert) {
   });
 });
 
+test('allows empty arrays', function(assert) {
+  compute({
+    assert,
+    computed: divide(emberA()),
+    strictEqual: 0
+  });
+});
+
+test('divides array members', function(assert) {
+  compute({
+    assert,
+    computed: divide(emberA([3, 2]), emberA([1])),
+    strictEqual: 1.5
+  });
+});
+
 test('handles all undefined', function(assert) {
   compute({
     assert,

tests/integration/multiply-test.js

@@ -1,5 +1,6 @@
 import { multiply } from 'ember-awesome-macros';
 import { module, test } from 'qunit';
+import { A as emberA } from 'ember-array/utils';
 import compute from 'ember-macro-test-helpers/compute';
 
 module('Integration | Macro | multiply');
@@ -29,6 +30,22 @@ test('multiplies three numbers', function(assert) {
   });
 });
 
+test('allows empty arrays', function(assert) {
+  compute({
+    assert,
+    computed: multiply(emberA()),
+    strictEqual: 0
+  });
+});
+
+test('multiplies array members', function(assert) {
+  compute({
+    assert,
+    computed: multiply(emberA([1, 2]), emberA([3])),
+    strictEqual: 6
+  });
+});
+
 test('handles all undefined', function(assert) {
   compute({
     assert,

tests/integration/subtract-test.js

@@ -1,5 +1,6 @@
 import { subtract } from 'ember-awesome-macros';
 import { module, test } from 'qunit';
+import { A as emberA } from 'ember-array/utils';
 import compute from 'ember-macro-test-helpers/compute';
 
 module('Integration | Macro | subtract');
@@ -29,6 +30,22 @@ test('subtracts three numbers', function(assert) {
   });
 });
 
+test('allows empty arrays', function(assert) {
+  compute({
+    assert,
+    computed: subtract(emberA()),
+    strictEqual: 0
+  });
+});
+
+test('subtracts array members', function(assert) {
+  compute({
+    assert,
+    computed: subtract(emberA([3, 2]), emberA([1])),
+    strictEqual: 0
+  });
+});
+
 test('handles all undefined', function(assert) {
   compute({
     assert,