将类型转换为数组-GO语法

Question

In the below syntax_1,

 array := [...]float64{7.0, 8.5, 9.1}

and syntax_2,

type People interface {
    SayHello()
    ToString()
}

type Student struct {
    Person
    university string
    course string
}

type Developer struct {
    Person
    company string
    platform string
}


func main(){

    alex := Student{Person{"alex", 21, "111-222-XXX"}, "MIT","BS CS"}
    john := Developer{Person{"John", 35, "111-222-XXX"}, "Accel North America", "Golang"}
    jithesh := Developer{Person{"Jithesh", 33, "111-222-XXX"}, "Accel North America", "Hadoop"}
    //An array with People types    
    peopleArr := [...]People{alex, john,jithesh}
}

---

1) What does this syntax float64{7.0, 8.5, 9.1} & People{alex, john,jithesh} mean? this looks like a paradigm(a way of programming) more than a syntax

2) Can you provide reference to the meaning/purpose of [...] syntax? I see converting something to an [] type

Answer 1

Squiggly brackets are used to define a composite literal. A value that contains more than one value inside it. In your first example an array of float values is created [...]float64{7.0, 8.5, 9.1} is a literal for an array of floats with 3 elements. In your second example, a few literals for predefined struct types are created and another array. Person{"alex", 21, "111-222-XXX"} is a literal for a struct of type Person. And [...]People{alex, john,jithesh} is an array of type People containing 3 elements.