Kotlin 简单优雅的高阶函数Kotlin 简单优雅的高阶函数《Kotlin极简教程》正式上架：1 . Kotlin 函数式编程： 函数的组合。一切皆是函数。2. 简单好用的 Kotlin 类型别名

fun main(args: Array<String>) {
    val h = h(::g, ::f)
    val strList = listOf("a", "ab", "abc","abcd","abcde","abcdef","abcdefg")
    // 非常好用的流式 API filter，flat，map 等等
    val mstrList = strList.filter(h)
    println(mstrList)
    mstrList.forEachIndexed{
        index,value ->
        println("$value = ${value.length}")
    }
}

// 简单好用的 Kotlin 类型别名
typealias G=(String) -> Int
typealias F=(Int) -> Boolean
typealias H=(String) -> Boolean

// 简单直接的函数定义
fun f(x: Int) = x % 2 != 0
fun g(s: String) = s.length

// 简单优雅的高阶函数定义（复合函数）： compose(f, g) = f(g(*))
fun h( g: G, f: F): H {
    return { x -> f(g(x)) }
}

typealias G=(String) -> Int
typealias F=(Int) -> Boolean
typealias H=(String) -> Boolean

val mstrList = strList.filter(h)

mstrList.forEachIndexed{
        index,value ->
        println("$value = ${value.length}")
 }

fun h( g: G, f: F): H {
    return { x -> f(g(x)) }
}

    val h = h(::g, ::f)
    val strList = listOf("a", "ab", "abc","abcd","abcde","abcdef","abcdefg")
    // 非常好用的流式 API filter，flat，map 等等
    val mstrList = strList.filter(h)

package com.easy.kotlin;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

interface G {
    Integer apply(String s);
}

interface F {
    Boolean apply(Integer x);
}

interface H {
    Boolean apply(String s);
}

public class InterfaceInvokeDemo {
    public static void main(String[] args) {
        G g = (s) -> s.length();
        F f = (x) -> x % 2 != 0;
        H h = (s) -> f.apply(g.apply(s));

        List<String> strings = Arrays.asList(new String[] {"a", "ab", "abc", "abcd", "abcde", "abcdef", "abcdefg"});
        List<String> result = new ArrayList();

        for (String s : strings) {
            if (h.apply(s)) {
                result.add(s);
            }
        }

        System.out.println(result);
    }
}