Go Cheatsheet

// Basic function
func greet(name string) string {
    return fmt.Sprintf("Hello, %s", name)
}

// Multiple return values
func divmod(a, b int) (int, int) {
    return a / b, a % b
}

// Variadic
func sum(nums ...int) int {
    total := 0
    for _, n := range nums {
        total += n
    }
    return total
}

// Function as value
square := func(x int) int { return x * x }

// for (the only loop)
for i := 0; i < 5; i++ {
    fmt.Println(i)
}

// range over slice
for i, v := range []int{1, 2, 3} {
    fmt.Println(i, v)
}

// range over map
for k, v := range map[string]int{"a": 1} {
    fmt.Println(k, v)
}

// while-like
n := 0
for n < 5 {
    n++
}

// Goroutines
go func() {
    fmt.Println("running concurrently")
}()

// Channels
ch := make(chan int, 2)
ch <- 42
val := <-ch

// WaitGroup
var wg sync.WaitGroup
for i := 0; i < 5; i++ {
    wg.Add(1)
    go func(id int) {
        defer wg.Done()
        fmt.Printf("Worker %d\n", id)
    }(i)
}
wg.Wait()

// select (multiplex channels)
select {
case msg := <-ch1:
    fmt.Println(msg)
case msg := <-ch2:
    fmt.Println(msg)
case <-time.After(time.Second):
    fmt.Println("timeout")
}

// Mutex
var mu sync.Mutex
mu.Lock()
// critical section
mu.Unlock()