Hoja de referencia de Go Maps

// define map
var m1 map[int]string
// instantiate map
m1 = make(map[int]string)
// implict map instantiation
m2 := make(map[int]string)
// map literal
m3 := map[int]string{
1:  “One”,
9:  “Nine”
}

m := map[int]string{
    1:  "One",
    9:  "Nine"
}
m[10] = "Ten"
// m contains 1, 9, 10

m := map[int]string{
    1:  "One",
    9:  "Nine"
}
item, ok := m[9]   //item is "Nine; ok is true if the
                    //key was found, false otherwise

m := map[int]string{
    1:  "One",
    9:  "Nine"
}
delete(m, 9)
//m contains only the `1` item

m := map[int]string{
    1:  "One",
    9:  "Nine"
}
m = make(map[int]string) // m is an initialized, empty map

m := map[int]string{
    1:  "One",
    9:  "Nine"
}
l := len(m) // l == 2

keys := make([]string, 0, len(m))
for k := range m {
    keys = append(keys, k)
}