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Channels Review

Here are a few extra things you should understand about channels from Dave Cheney's awesome article.

A Declared but Uninitialized Channel Is Nil Just Like a Slice

var s []int       // s is nil
var c chan string // c is nil

var s = make([]int, 5) // s is initialized and not nil
var c = make(chan int) // c is initialized and not nil

A Send to a Nil Channel Blocks Forever

var c chan string        // c is nil
c <- "let's get started" // blocks

A Receive from a Nil Channel Blocks Forever

var c chan string // c is nil
fmt.Println(<-c)  // blocks

A Send to a Closed Channel Panics

var c = make(chan int, 100)
close(c)
c <- 1 // panic: send on closed channel

A Receive from a Closed Channel Returns the Zero Value

var c = make(chan int, 100)
close(c)
fmt.Println(<-c) // 0

Any buffered values are received first. Once the buffer is empty, receives return the zero value.