コレクションをぶんまわしてみる

gistfile1.groovy

List list = [
    [color:"blue", weight:10],
    [color:"red", weight:30],
    [color:"blue", weight:50],
]

// Javaで
int weight1 = 0;
for (def e : list) {
    if ("blue".equals(e.color))
        weight1 += e.weight;
}
assert weight1 == 60

// groovyで
int weight2 = list
    .findAll { it.color == 'blue' }
    .inject(0) { acc, e -> acc + e.weight }
assert weight2 == 60


// Lambdaだとこうなるっぽい？
int weight3 = list
    .filter { it -> "blue".equals(it.color) }
    .reduce (0, { (acc, e) -> acc + e.weight });
assert weight3 == 60

//Scalaだとこうだ！
val weight4: Int = list.filter(_.color == "blue").map(_.weight).sum