Question

Edit: Jeremy Wall helped me realize I had asked a question more specific than I intended; here’s a better version.

Say I want to represent a table associating of values of some type B to sequences of values of some type A for which equality is defined. What is the best way to do that in Go?

Obviously for the table I’d want to use a Go map, but what can I use for the sequences of values of type A? Slices cannot be used as keys for maps in Go; arrays can, but the length of an array is a part of it’s type and I’m interested in being able to use sequences of length determined at runtime. I could (1) use arrays of A declaring a maximum length for them or (2) use slices of A, serialize them to strings for use as keys (this technique is familiar to Awk and Lua programmers…). Is there a better work around for this “feature” of Go than the ones I’ve described?

As pointed out by Jeremy Wall in answer to my original version of the question, where I had A = int, option (2) is pretty good for integers, since you can use slices of runes for which conversion to string is just a cast.

Answer 1

Will a sequence of rune instead of integers work for you? runes are uint32 and the conversion to a string is just a cast:

package main

import "fmt"

type myKey struct {
  seq []int
}

func main() {
    m := make(map[string]string)
    key := []rune{1, 2}
    m[string(key)] = "foo"
    fmt.Print("lookup: ", m[string(key)])
}

You can play with this code here: http://play.golang.org/p/Kct1dum8A0