匿名函数中的println为何不会打印出来

scala> def t = (t1: Int, t2: Int)=>println("scala")
t: (Int, Int) => Unit

scala> def t = (t1: Int, t2: Int)=>{println("scala");1+2}
t: (Int, Int) => Int

scala> def t = (t1: Int, t2: Int)=>{println("scala"); t1+t2}
t: (Int, Int) => Int

scala> def t = (t1: Int, t2: Int)=>{println("scala"); t1+"12"}
t: (Int, Int) => String

执行下面的代码

   def t=(t1:Int,t2:Int)=>{println("scala");t1+"t3"}
    println(t(1,2))

打印结果：

1t3

为何匿名函数中的println不打印出来???????