generics

go/02-next-level/05-generics.go

@@ -2,7 +2,7 @@ package main
 
 import "fmt"
 
-func SlicesIndex[S []E, E int](s []string, v string) int {
+func SlicesIndex[S []E, E comparable](s S, v E) int {
 	for i := range s {
 		if v == s[i] {
 			return i
@@ -11,27 +11,27 @@ func SlicesIndex[S []E, E int](s []string, v string) int {
 	return -1
 }
 
-type List struct {
-	head, tail *element
+type List[T any] struct {
+	head, tail *element[T]
 }
 
-type element struct {
-	next *element
-	val  int
+type element[T any] struct {
+	next *element[T]
+	val  T
 }
 
-func (lst *List) Push(v int) {
+func (lst *List[T]) Push(v T) {
 	if lst.tail == nil {
-		lst.head = &element{val: v}
+		lst.head = &element[T]{val: v}
 		lst.tail = lst.head
 	} else {
-		lst.tail.next = &element{val: v}
+		lst.tail.next = &element[T]{val: v}
 		lst.tail = lst.tail.next
 	}
 }
 
-func (lst *List) AllElements() []int {
-	var elems []int
+func (lst *List[T]) AllElements() []T {
+	var elems []T
 	for e := lst.head; e != nil; e = e.next {
 		elems = append(elems, e.val)
 	}
@@ -40,12 +40,17 @@ func (lst *List) AllElements() []int {
 
 func main() {
 	var s = []string{"foo", "bar", "zoo"}
-
 	fmt.Println("index of zoo:", SlicesIndex(s, "zoo"))
 
-	lst := List{}
+	_ = SlicesIndex[[]string, string](s, "zoo")
+
+	var s2 = []int{2, 4, 5, 6}
+	fmt.Println("index of 4: ", SlicesIndex(s2, 4))
+
+	lst := List[float64]{}
 	lst.Push(10)
 	lst.Push(13)
 	lst.Push(23)
+	lst.Push(23.3)
 	fmt.Println("list:", lst.AllElements())
 }