If the top-level type is just a type name, you can omit it from the elements of the literal.
package main import "fmt" type Vertex struct { Lat, Long float64 } var m = map[string]Vertex { "Bell Labs": {40.68433,-74.39967}, "Google": {37.42202, -122.08408}, } func main() { var m2 map[int]uint8 m2 = make(map[int]uint8) m2[12] = uint8(12) m2[1] = uint8(1) fmt.Println(m) fmt.Println(m2) }