diff --git a/00-notes.txt b/00-notes.txt
index e1bd62c..3d28281 100644
--- a/00-notes.txt
+++ b/00-notes.txt
@@ -29,3 +29,4 @@
   * deploying to heroku
   * sort-by
   * errors
+  * compilation
diff --git a/xx-exit b/xx-exit
deleted file mode 100755
index c3f482c..0000000
Binary files a/xx-exit and /dev/null differ
diff --git a/xx-file-open.go b/xx-file-open.go
new file mode 100644
index 0000000..7dc5739
--- /dev/null
+++ b/xx-file-open.go
@@ -0,0 +1,18 @@
+package main
+
+import ("fmt"; "os")
+
+func main() {
+    file, err := os.Open("xx-file-open.go")
+    if err != nil {
+        panic(err)
+    }
+    defer file.Close()
+    
+    stat, err := file.Stat()
+    if err != nil {
+        panic(err)
+    }
+
+	fmt.Println("Program has", stat.Size(), "bytes")
+}
diff --git a/xx-file-read.go b/xx-file-read.go
new file mode 100644
index 0000000..ef5369d
--- /dev/null
+++ b/xx-file-read.go
@@ -0,0 +1,11 @@
+package main
+
+import ("fmt"; "io/ioutil")
+
+func main() {
+    contents, err := ioutil.ReadFile("xx-file-read.go")
+    if err != nil {
+        return
+    }
+    fmt.Print(string(contents))
+}
diff --git a/xx-file-write.go b/xx-file-write.go
new file mode 100644
index 0000000..8dd64df
--- /dev/null
+++ b/xx-file-write.go
@@ -0,0 +1,12 @@
+package main
+
+import "os"
+
+func main() {
+	file, err := os.Create("xx-file-write.txt")
+    if err != nil {
+        panic(err)
+    }
+    defer file.Close()
+    file.WriteString("contents\n")
+}
diff --git a/xx-sort.go b/xx-sort.go
new file mode 100644
index 0000000..b5c2324
--- /dev/null
+++ b/xx-sort.go
@@ -0,0 +1,12 @@
+package main
+
+import ("fmt"; "sort")
+
+func main() {
+	strs := []string{"foo", "bar", "bat"}
+	fmt.Println(strs)
+	fmt.Println()
+
+	sort.Strings(strs)
+	fmt.Println(strs)
+}