a = 10              // int, 整数除法截断: 10/3 == 3
name = "yaklang"    // string
ok = true           // bool
pi = 3.14           // float

nums = [1, 2, 3]            // 切片 (动态数组)
nums = append(nums, 4, 5)   // append 可追加多个
sub = nums[1:3]            // 切片表达式 -> [2, 3]

m = {"host": "a.com", "port": 443}  // map
v = m["port"]                        // 取值
exist = "host" in m                  // in 判断 key 是否存在
delete(m, "port")                    // 删除 key

for i := 0; i < 5; i++ { sum += i }   // 经典三段式 for

for v in [10, 20, 30] { total += v }  // for-in: 单变量 = 元素值 (推荐)

if score >= 90 {
    grade = "A"
} else if score >= 60 {
    grade = "B"
} else {
    grade = "C"
}

add = func(a, b) { return a + b }     // func 字面量
add = fn(a, b) { return a + b }       // fn / def 等价于 func
func named(a, b) { return a + b }     // 命名函数

twice = (x) => { return x * 2 }       // 箭头函数 (热加载 hook 常用写法)

addsub = func(a, b) { return a + b, a - b }   // 多返回值
s, d = addsub(7, 3)                            // 多重赋值

makeCounter = func() {                 // 闭包: 捕获并保持状态
    n = 0
    return func() { n++; return n }
}

sumAll = func(args...) {               // 可变参数
    t = 0
    for v in args { t += v }
    return t
}

beforeRequest = func(https, originReq, req) { return req }
hijackHTTPRequest = (isHttps, url, req, forward, drop) => { forward(req) }

line = f"user=${user} port=${port}"   // -> "user=admin port=8080"
msg = sprintf("%d-%s", 7, "x")        // -> "7-x"

// 1) 手动判断 (最显式, 可自定义降级)
ret, err = codec.DecodeBase64(s)
if err != nil { /* 降级或 return */ }

// 2) die: err 非 nil 才 panic
ret, err = codec.DecodeBase64(s)
die(err)

// 3) ~ 波浪号 (WavyCall): 出错即自动 panic, "出错就该终止"时最简洁
ret = codec.DecodeBase64(s)~

defer func {
    e = recover()
    if e != nil { log.error("caught: %v", e) }
}

cd /Users/v1ll4n/Projects/yaklang
go run common/yak/cmd/yak.go skills/yaklang-syntax/examples/syntax-tour.yak
go run common/yak/cmd/yak.go skills/yaklang-syntax/examples/error-handling.yak