在 Java 9 的JShell中 跟Kotlin 的REPL中尽情体验函数式编程乐趣吧《Kotlin极简教程》正式上架：

jshell> List<String> alphabet = List.of("a","b","c")
alphabet ==> [a, b, c]

jshell> alphabet.stream().map((e) -> {return e.toUpperCase();}).collect(Collectors.toList());
$6 ==> [A, B, C]

jshell> alphabet
alphabet ==> [a, b, c]

>>> val alphabet = listOf("a","b","c")
>>> alphabet
[a, b, c]
>>> alphabet.map{it->it.toUpperCase()}
[A, B, C]
>>> alphabet
[a, b, c]