existsとforall

scala >

//hogeが含まれているか
scala> List("hoge", "hoge").exists(s => s == "hoge")
res90: Boolean = true

//全部hogeかどうか
scala> List("hoge", "hoge").forall(s => s == "hoge")
res91: Boolean = true

//hogeが含まれているか
scala> List("hoge", "foo").exists(s => s == "hoge")
res92: Boolean = true

//全部hogeかどうか
scala> List("hoge", "foo").forall(s => s == "hoge")
res93: Boolean = false