Go Structs & Maps

v := &Vertex{1, 2}
v.X = 2

Doing v.X is the same as doing (*v).X, when v is a pointer.

m := make(map[string]int)
m["k1"] = 7
m["k2"] = 13
fmt.Println(m) // => map[k1:7 k2:13]
v1 := m["k1"]
fmt.Println(v1)     // => 7
fmt.Println(len(m)) // => 2
delete(m, "k2")
fmt.Println(m) // => map[k1:7]
_, prs := m["k2"]
fmt.Println(prs) // => false
n := map[string]int{"foo": 1, "bar": 2}
fmt.Println(n) // => map[bar:2 foo:1]

v := Vertex{X: 1, Y: 2}
// Field names can be omitted
v := Vertex{1, 2}
// Y is implicit
v := Vertex{X: 1}

You can also put field names.

package main
import (
    "fmt"
)
type Vertex struct {
    X int
    Y int
}
func main() {
    v := Vertex{1, 2}
    v.X = 4
    fmt.Println(v.X, v.Y) // => 4 2
}

See: Structs