some experiments

README

@@ -15,6 +15,7 @@ get web presence in good enough shape to point to from blog post
     subscription management
 
 validate book style in editor
+  01-hello
   22-varags
   xx-rand
   xx-sha1

src/01-hello.go

@@ -1,11 +1,14 @@
+                                // Here's an example Go program.
+
 package main
 
 import "fmt"
 
 func main() {
-	fmt.Println("Hello, world")
+    fmt.Println("Hello world")  // It prints `Hello world`.
 }
 
-// == running
-// $ go run 01-hello.go
-// Hello, world
+/*
+$ go run 01-hello.go            // Use `go run` to run the program.
+Hello world
+*/

src/02-numbers.go

@@ -1,7 +0,0 @@
-package main
-
-import "fmt"
-
-func main() {
-    fmt.Println("1 + 1 =", 1 + 1)
-}

src/02-values.go

@@ -0,0 +1,22 @@
+                                        // Go has various value types, including strings,
+                                        // different types of numbers, booleans, etc.
+
+package main
+
+import "fmt"
+
+func main() {
+    fmt.Println("Hello world")          // Strings - you already saw these.
+    fmt.Println("Hello World"[1])
+    fmt.Println("Hello " + "World")
+
+    fmt.Println("1+1 =", 1+1)           // Integers and floats.
+    fmt.Println("7.0/3.0 =", 7.0/3.0)
+
+    fmt.Println(true && false)          // Booleans as you'd expect.
+    fmt.Println(true || false)
+    fmt.Println(!true)
+}
+
+                                         // This is just a sampling of Go's value types. We'll
+                                         // learn more about them as we go.

src/03-strings.go

@@ -1,9 +0,0 @@
-package main
-
-import "fmt"
-
-func main() {
-    fmt.Println(len("Hello World"))
-    fmt.Println("Hello World"[1])
-    fmt.Println("Hello " + "World")
-}

src/04-booleans.go

@@ -1,11 +0,0 @@
-package main
-
-import "fmt"
-
-func main() {
-    fmt.Println(true && true)
-    fmt.Println(true && false)
-    fmt.Println(true || true)
-    fmt.Println(true || false)
-    fmt.Println(!true)
-}

src/10-for.go

@@ -1,14 +1,20 @@
+                                   // `for` is Go's only looping construct. Below are two common
+                                   // forms.
+
 package main
 
 import "fmt"
 
 func main() {
-	i := 1
-	for i <= 10 {
+	i := 1                         // We initialize `i` with `1` and loop until it's 10.
+	for i <= 10 {                  
 		fmt.Println(i)
 		i = i + 1
 	}
-	for j := 1; j <= 10; j++ {
+
+	for j := 1; j <= 10; j++ {     // This is a common idiom. We can do it on one line.
 		fmt.Println(j)
 	}
 }
+
+                                   // There are other forms of `for`; we'll see them later.

src/21-returns.go

@@ -1,13 +1,22 @@
+                          // A function can return multiple values.
+
 package main
 
 import "fmt"
 
-func vals() (int, int) {
-	return 3, 7
+func vals() (int, int) {  // The `(int, int)` in this signature shows that the
+    return 3, 7           // function returns 2 ints.
+    
 }
 
 func main() {
-	x, y := vals()
-	fmt.Println(x)
-	fmt.Println(y)
+    x, y := vals()        // Use the 2 different return values from the call.
+    fmt.Println(x)
+    fmt.Println(y)
 }
+
+/*
+$ go run 21-returns.go
+3
+7
+*/

src/xx-sha1.go

@@ -1,25 +1,27 @@
-	                                        // `crypto/sha1` computes SHA1 hashes.
+                                         // `crypto/sha1` computes SHA1 hashes.
+                                         
+package main                             
+                                         
+import (                                 
+    "fmt"                                
+    "crypto/sha1"                        
+    "encoding/hex"                       
+)                                        
+                                         
+func main() {                            
+    h := sha1.New()                      // The pattern is `sha1.New()`, `sha1.Write(bytes)`,
+                                         // then `sha1.Sum([]byte{})
+                                         
+    h.Write([]byte("sha1 this string"))  // `Write` expects bytes. If you have a string `s`
+                                         // use `[]byte(s)` to coerce it.
+                                         
+    bs := h.Sum(nil)                     // Get the result. The argument to `Sum` can be used
+                                         // to append to an existing buffer: usually uneeded.
+                                         
+    fmt.Println(hex.EncodeToString(bs))  // SHA1 values are often printed in hex, for example
+                                         // with git.
+}                                        
 
-package main
-
-import (
-	"fmt"
-	"crypto/sha1"
-	"encoding/hex"
-)
-
-func main() {
-    h := sha1.New()                         // The basic pattern is `sha1.New()`, `sha1.Write(bytes)`, then
-                                            // `sha1.Sum([]byte{})
-
-    h.Write([]byte("sha1 this string"))     // `Write` expects bytes. If you have a string `s` use
-											// `[]byte(s)` to coerce it.
-
-    bs := h.Sum(nil)                        // Get the result. The argument to `Sum` can be used to append
-                                            // to an existing buffer, but usually you won't need it.
-
-	fmt.Println(hex.EncodeToString(bs))     // SHA1 values are often printed in hex, for example with git.
-}
-
-                                            // You can compute other hashes like MD5 using the same
-                                            // pattern. Import `crypto/md5` and use `md5.New()`.
+                                         // You can compute other hashes like MD5 using the
+                                         // same pattern. Import `crypto/md5` and use
+                                         // `md5.New()`.