How to create a Map<String, List<SomeClass>> in Go?

How do I create a Map<String, List<SomeClass>> in Go? Something like:

var m map[string]list
m = make(map[string]list)

You're looking for; map[string][]SomeClass

However, the way you're using make won't cut it. I would personally recommend using composite literal syntax for initialization, it would look like this;

m := map[string][]SomeClass {
      "a": []SomeClass{SomeClass{SomeProperty: SomeValue}}
}

If you want to use make, you'll have to iterate over the map and call make for every key or the []SomeClass array for that key is gonna be nil. My syntax initializes as follows; outer most braces is for the map, inside it I declare a single key "a" and initialize a slice of SomeClass, inside the slice I initialize an instance of SomceClass setting SomeProperty to SomeValue.

If you highly prefer using make for whatever reason I can add another example which initializes the collection that way, I just find it to be more complicated personally.

EDIT:

Here's some sample closer to what you might be looking for

var m map[string][]Model
m = make(map[string][]Model)

for i, _ := range Cars {
      m[Cars[i].Make] = append(m[Cars[i].Make], Cars[i].Model)
}

In this example I'm initialize the map, then I start iterating over the "cars" array. For each car I check to see if there is a key for it's Make if there is, then I append the Model to the slice with that key, otherwise, I instantiate a new slice with the model. Of course, that isn't actual working code but it should give you some idea. If you provide a more complete example (like a sample of the Cars data you want to put in the map) then I could tailor this more to your needs but I'm hoping that will give you the general idea.