next level starting point

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

@@ -0,0 +1,51 @@
+package main
+
+import "fmt"
+
+func SlicesIndex[S []E, E int](s []string, v string) int {
+	for i := range s {
+		if v == s[i] {
+			return i
+		}
+	}
+	return -1
+}
+
+type List struct {
+	head, tail *element
+}
+
+type element struct {
+	next *element
+	val  int
+}
+
+func (lst *List) Push(v int) {
+	if lst.tail == nil {
+		lst.head = &element{val: v}
+		lst.tail = lst.head
+	} else {
+		lst.tail.next = &element{val: v}
+		lst.tail = lst.tail.next
+	}
+}
+
+func (lst *List) AllElements() []int {
+	var elems []int
+	for e := lst.head; e != nil; e = e.next {
+		elems = append(elems, e.val)
+	}
+	return elems
+}
+
+func main() {
+	var s = []string{"foo", "bar", "zoo"}
+
+	fmt.Println("index of zoo:", SlicesIndex(s, "zoo"))
+
+	lst := List{}
+	lst.Push(10)
+	lst.Push(13)
+	lst.Push(23)
+	fmt.Println("list:", lst.AllElements())
+}

go/02-next-level/06-defer.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func main() {
+	f := createFile("/tmp/defer.txt")
+	writeFile(f)
+	closeFile(f)
+}
+
+func createFile(p string) *os.File {
+	fmt.Println("creating")
+	f, err := os.Create(p)
+	if err != nil {
+		panic(err)
+	}
+	return f
+}
+
+func writeFile(f *os.File) {
+	fmt.Println("writing")
+	fmt.Fprintln(f, "data")
+}
+
+func closeFile(f *os.File) {
+	fmt.Println("closing")
+	err := f.Close()
+
+	if err != nil {
+		panic(err)
+	}
+}