ScalaのcomposeとandThen
f(g(x))なのかg(f(x))なのかすぐにわすれちゃう。メモしておこう。
scala> val f = (x: Int) => 2 * x f: (Int) => Int = <function1> scala> val g = (x: Int) => x + 1 g: (Int) => Int = <function1> scala> f(g(1)) res9: Int = 4 scala> (f compose g)(1) res10: Int = 4 scala> g(f(1)) res11: Int = 3 scala> (f andThen g)(1) res12: Int = 3 scala>