使用Scala 2.8.1,编译此:为什么Scala使用元组进行表达无法编译?
val t = (40, 2)
println(for ((i, j) <- List(t)) yield i + j)
val e: Either[String, (Int, Int)] = Right(t)
println(e.right.map {
case (i, j) => i + j
})
println(for ((i, j) <- e.right) yield i + j)
给出了这样的:
test.scala:9: error: constructor cannot be instantiated to expected type;
found : (T1, T2)
required: Either[Nothing,(Int, Int)]
println(for ((i, j) <- e.right) yield i + j)
根据Scala中编程,所述用于表达应相当于在地图/情况下表达,但是只有后者才会编译。我做错了什么,我该怎么做?