A Tour of Go - Generics

Question 1

What are generic functions in Go?

Answer 1

Go functions can be written to work on mulitple types using type parameters.

Question 2

How is a generic function declared?

Answer 2

The type parameters of a function appear between brackets, before the function’s arguments.

func Index[T comparable](s []T, x T) int

This declaration means that s is a slice of any type T that fulfils the built-in constraint comparable. x is also a value of the same type.

Question 3

What is the comparable constraint?

Answer 3

comparable is a useful constraint that makes it possible to use the == and != operators on values of the type.

Question 4

Give an example of a generic function that compares a value to all slice elements until a match is found?

Answer 4

func Index[T comparable](s []T, x T) int {
	for i, v := range s {
		if v == x {
			return i
		}
	}
	return -1
}

Question 5

What are generic types in Go?

Answer 5

A type can be parameterised with a type parameter, which could be useful for implementing generic data structures.

Question 6

Give an example of a generic list type?

Answer 6

type List[T any] struct {
	next *List[T]
	val  T
}