Merge pull request vavr-io#208 from danieldietrich/master

Fixes vavr-io#207: numeric operations of traversables

pom.xml

@@ -58,6 +58,11 @@
         <scala.version>2.11.6</scala.version>
     </properties>
     <build>
+        <resources>
+            <resource>
+                <directory>src/main/javascript</directory>
+            </resource>
+        </resources>
         <plugins>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>

src/main/java/javaslang/test/Gen.java

@@ -215,7 +215,7 @@ Gen<T> gen(int n, Stream<Tuple2<Integer, Gen<T>>> stream) {
                 return (n <= k) ? stream.head()._2 : gen(n - k, stream.tail());
             }
         }
-        final int size = stream.map(t -> t._1).sum();
+        final int size = stream.foldLeft(0, (i, t) -> i + t._1);
         return choose(1, size).flatMap(n -> new Frequency().gen(n, stream));
     }
 

src/main/javascript/javaslang/collection/traversable.js

@@ -0,0 +1,44 @@
+/*
+ * Computes the sum of iterable elements as double.
+ */
+var avg = function(iterable) {
+    // division by zero is NaN
+    return compute(iterable, 0.0, function(acc, value) { return acc + value }, function(acc, count) { return acc / count })
+}
+
+/*
+ * Computes the product of iterable elements as double.
+ */
+var product = function(iterable) {
+    return compute(iterable, 1.0, function(acc, value) { return acc * value }, function(acc, count) { return acc })
+}
+
+/*
+ * Computes the sum of iterable elements as double.
+ */
+var sum = function(iterable) {
+    return compute(iterable, 0.0, function(acc, value) { return acc + value }, function(acc, count) { return acc })
+}
+
+/*
+ * Represents a computation given iterable elements.
+ *
+ * @param iterable A java.lang.Iterable of arbitrary objects.
+ * @param zero The neutral element regarding the accumulate operation.
+ * @param accumulate(acc, value) Accumulates the current accumulator with the given value.
+ * @param result(acc, count) Computes the result given the accumulator and the element count.
+ * @return a double value or NaN if an element has no numerical representation using parseFloat()
+ */
+var compute = function(iterable, zero, accumulate, result) {
+    var acc = zero
+    var count = 0
+    for each (elem in iterable) {
+        var float = parseFloat(elem)
+        if (isNaN(float)) {
+            return float
+        }
+        acc = accumulate(acc, float)
+        count += 1
+    }
+    return result(acc, count)
+}