Added generic list example

list/list.go

@@ -0,0 +1,58 @@
+package list
+
+import (
+	"errors"
+	"fmt"
+)
+
+type List[T any] struct {
+	arr []T
+}
+
+func (l *List[T]) Add(item ...T) {
+	l.arr = append(l.arr, item...)
+}
+
+type FindFn[T any] func(index int, item T) bool
+
+func (l *List[T]) FindWhere(fn FindFn[T]) (int, error) {
+	for i, v := range l.arr {
+		if fn(i, v) {
+			return i, nil
+		}
+	}
+	return -1, nil
+}
+
+func (l *List[T]) Remove(index int) error {
+	if err := l.checkIndex(index); err != nil {
+		return err
+	}
+	l.arr = append(l.arr[:index], l.arr[index+1:]...)
+	return nil
+}
+
+func (l *List[T]) Update(index int, value T) error {
+	if err := l.checkIndex(index); err != nil {
+		return err
+	}
+	l.arr[index] = value
+	return nil
+}
+
+func (l *List[T]) checkIndex(index int) error {
+	if index < 0 || index > (len(l.arr)-1) {
+		return errors.New("index out of bounds")
+	}
+	return nil
+}
+
+func (l *List[T]) String() string {
+	return fmt.Sprintf("%v len=%d cap=%d", l.arr, len(l.arr), cap(l.arr))
+}
+
+func NewList[T any]() *List[T] {
+	return &List[T]{
+		arr: []T{},
+	}
+}

list/list_test.go

@@ -0,0 +1,38 @@
+package list_test
+
+import (
+	"fmt"
+	"github.com/coruna-gophers/generics-poc/list"
+	"testing"
+)
+
+func TestList(t *testing.T) {
+	l := list.NewList[int]()
+	fmt.Println(l)
+
+	l.Add(1, 2, 3)
+	fmt.Println(l)
+
+	l.Remove(0)
+	fmt.Println(l)
+
+	l.Add(4)
+	fmt.Println(l)
+
+	l.Add(5, 6)
+	fmt.Println(l)
+
+	l.Update(3, 10)
+	fmt.Println(l)
+
+	var findFn list.FindFn[int]
+	findFn = func(index int, item int) bool {
+		return item%2 == 0
+	}
+
+	index, err := l.FindWhere(findFn)
+	if err != nil {
+		t.Fatalf("error finding first even element: %v", err)
+	}
+	fmt.Printf("first event element at %d\n", index)
+}