Dev Stack Source

Answer : You almost have the right thing however your syntax for the inner arrays is slightly off, needing curly braces like; test := [][]int{[]int{1,2,3},[]int{1,2,3}} or a slightly more concise version; test := [][]int{{1,2,3},{1,2,3}} The expression is called a 'composite literal' and you can read more about them here; https://golang.org/ref/spec#Composite_literals But as a basic rule of thumb, if you have nested structures, you have to use the syntax recursively. It's very verbose. In some other langauges (Perl, Python, JavaScript), [1,2,3] might be an array literal, but in Go, composite literals use braces, and here, you have to specify the type of the outer slice: package main import "fmt" type T struct{ foo [][]int } func main() { a := [][]int{{1, 2, 3}, {4, 5, 6}} b := T{foo: [][]int{{1, 2, 3}, {4, 5, 6}}} fmt.Println(a, b) } You can run or play with that on the Playground. The Go compiler is just tricky enough to figure out that the eleme...

Answer : Make IDs a []string and convert the integers when you append them var IDs []string for _, i := range []int{1, 2, 3, 4} { IDs = append(IDs, strconv.Itoa(i)) } fmt.Println(strings.Join(IDs, ", ")) https://play.golang.org/p/xrfuMRjgiI I would prefer to use json.Marshal . It is much simple and easy to use. data := []int{100, 200, 300} s, _ := json.Marshal(data) fmt.Println(strings.Trim(string(s), "[]")) GoPlaygroundLink I hope this helps you. Please feel free to ask in case of doubts. WebsiteLink

Answer : Since May 14th, 2019, it is now possible (from Brad Fitzpatrick)! The #golang playground now supports third-party imports, pulling them in via https://proxy.golang.org/ Example: https://play.golang.org/p/eqEo7mqdS9l Multi-file support & few other things up next. Report bugs at golang/go issue 31944, or here on the tweeters. (On the "multiple file" support , see, since May. 16th 2019, "Which packages may be imported in the go playground?": see an example here) netbrain suggests in the comments another example: On the playground: package main import ( "fmt" "gonum.org/v1/gonum/mat" ) func main() { v1 := mat.NewVecDense(4,[]float64{1,2,3,4}) fmt.Println(mat.Dot(v1,v1)) } woud give '30', using mat.NewVecDense() to create a column vector, and mat.Dot() to return the sum of the element-wise product of v1 and v1 The point being: gonum/mat is not part of the Go Standard Library. Original ans...

Answer : [Update: as of Go 1.8, GOPATH defaults to $HOME/go , but you may still find this useful if you want to understand the GOPATH layout, customize it, etc.] The official Go site discusses GOPATH and how to lay out a workspace directory. export GOPATH="$HOME/your-workspace-dir/" -- run it in your shell, then add it to ~/.bashrc or equivalent so it will be set for you in the future. Go will install packages under src/ , bin/ , and pkg/ , subdirectories there. You'll want to put your own packages somewhere under $GOPATH/src , like $GOPATH/src/github.com/myusername/ if you want to publish to GitHub. You'll also probably want export PATH=$PATH:$GOPATH/bin in your .bashrc so you can run compiled programs under $GOPATH . Optionally, via Rob Pike, you can also set CDPATH so it's faster to cd to package dirs in bash: export CDPATH=.:$GOPATH/src/github.com:$GOPATH/src/golang.org/x means you can just type cd net/html instead of cd $GOPATH/src/golang....

Answer : Create a single log.Logger and pass it around? That is possible. A log.Logger can be used concurrently from multiple goroutines. Pass around a pointer to that log.Logger? log.New returns a *Logger which is usually an indication that you should pass the object around as a pointer. Passing it as value would create a copy of the struct (i.e. a copy of the Logger) and then multiple goroutines might write to the same io.Writer concurrently. That might be a serious problem, depending on the implementation of the writer. Should each goroutine or function create a logger? I wouldn't create a separate logger for each function or goroutine. Goroutines (and functions) are used for very lightweight tasks that will not justify the maintenance of a separate logger. It's probably a good idea to create a logger for each bigger component of your project. For example, if your project uses a SMTP service for sending mails, creating a separate logger for the mail ser...