(WIP) Fun with Go's range over function types

A quick look at range-aware custom iterators.

Since Go 1.23, you can add support for the range construct to user-defined types. This provides a standard interface for iteration, which should make it easier for those experimenting with third-party containers.

To start off, there’s been nice feature since 1.22 more or less on the same topic:

A terser syntax for iterating over integers in the range [0, n). Similar to APL’s Iota primitive.

Example: Iterating from [0, 10)

for i := range 10 {
    fmt.Printf("i = %v\n", i)
}

Since the loop variable is optional, if we simply want to execute an action, say 3 times, the code boils down to:

for range 3 {
    fmt.Println("some-action")
}