Go: Design Patterns for Real-World Projects

The slice type

The slice type is commonly used as the idiomatic construct for indexed data in Go. The slice is more flexible and has many more interesting characteristics than arrays. The slice itself is a composite type with semantics similar to arrays. In fact, a slice uses an array as its underlying data storage mechanism. The general form of a slice type is given as follows:

[ ]<element_type>

The one obvious difference between a slice and an array type is omission of the size in the type declaration, as shown in the following examples:

var ( 
    image []byte      
    ids []string 
    vector []float64 
    months []string 
    q1 []string 
    histogram []map[string]int // slice of map (see map later) 
) 

golang.fyi/ch07/slicetypes.go

The missing size attribute in the slice type ...