Pair/tuple data type in Go

go tuples

While doing the final exercise of the Tour of Go, I decided I needed a queue of (string, int) pairs. That's easy enough:

type job struct {
    url string
    depth int
}

queue := make(chan job)
queue <- job{url, depth}

But this got me thinking: are there built-in pair/tuple data types in Go? There is support for returning multiple values from a function, but AFAICT, the multiple value tuples produced are not first-class citizens in Go's type system. Is that the case?

As for the "what have you tried" part, the obvious syntax (from a Python programmer's POV)

queue := make(chan (string, int))

didn't work.

You can do this. It looks more wordy than a tuple, but it's a big improvement because you get type checking.

Edit: Replaced snippet with complete working example, following Nick's suggestion. Playground link: http://play.golang.org/p/RNx_otTFpk

package main

import "fmt"

func main() {
    queue := make(chan struct {string; int})
    go sendPair(queue)
    pair := <-queue
    fmt.Println(pair.string, pair.int)
}

func sendPair(queue chan struct {string; int}) {
    queue <- struct {string; int}{"http:...", 3}
}

Anonymous structs and fields are fine for quick and dirty solutions like this. For all but the simplest cases though, you'd do better to define a named struct just like you did.

There is no tuple type in Go, and you are correct, the multiple values returned by functions do not represent a first-class object.

Nick's answer shows how you can do something similar that handles arbitrary types using interface{}. (I might have used an array rather than a struct to make it indexable like a tuple, but the key idea is the interface{} type)

My other answer shows how you can do something similar that avoids creating a type using anonymous structs.

These techniques have some properties of tuples, but no, they are not tuples.

Pair/tuple data type in Go

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