Merge branch 'master' into clipboard

.env

@@ -1,2 +0,0 @@
-CANONICAL_HOST=127.0.0.1
-FORCE_HTTPS=0

.gitattributes

@@ -0,0 +1,3 @@
+public/* linguist-generated=true
+vendor/* linguist-vendored=true
+

.gitignore

@@ -1,2 +1,3 @@
-.anvil
 *.pyc
+.idea
+.vscode

.godir

@@ -1 +0,0 @@
-gobyexample

.travis.yml

@@ -0,0 +1,18 @@
+language: go
+
+go:
+  - 1.12
+
+before_install:
+  # We need Python to run pygmentize for generating HTML.
+  - sudo apt-get update
+  - sudo apt-get install python
+
+install:
+  - go get -u github.com/russross/blackfriday
+
+script:
+  - tools/build
+
+env:
+  - VERBOSE=1 TESTING=1

CONTRIBUTING.md

@@ -1,18 +1,18 @@
 ## Contributing
 
-Go by Example is now in a steady state. We are maintaining it, but are not
-expanding or significantly changing it any more.
+Thanks for your interest in contributing to Go by Example!
 
-With that in mind here are some specific contribution guidelines:
+* When sending a PR that affects the displayed contents of the site, run
+  `tools/build` locally and include the generated HTML in the PR. If you
+  only want to submit a simple typo suggestion (for example, through the
+  Github website), feel free to send a PR anyway - we'll regenerate the
+  HTML and merge with your commit.
 
-* If you see a typo or would like to suggest another small change, editing the
-  .go or .sh source file should be sufficient for the PR. I can rebuild the
-  HTML when I review the change.
+* We're open to adding more examples to the site. They should be on things
+  used by many programmers and only require the standard library. If you're
+  interested in adding an example, _please open an issue to discuss the topic
+  first_.
 
-* We are not going to add any more sections to the site. There are many
-  important topics that Go by Example doesn't cover, which we leave to other
-  resources.
-
-* We are not going to change the navigation of the site, in particular adding
+* We're not going to change the navigation of the site, in particular adding
   a "previous section" link or an "index" link other than the on the title
   text.

README.md

@@ -1,9 +1,8 @@
-## Go by Example
+# Go by Example
 
 Content and build toolchain for [Go by Example](https://gobyexample.com),
 a site that teaches Go via annotated example programs.
 
-
 ### Overview
 
 The Go by Example site is built by extracting code and
@@ -17,9 +16,10 @@ The built `public` directory can be served by any
 static content system. The production site uses S3 and
 CloudFront, for example.
 
-
 ### Building
 
+[![Build Status](https://travis-ci.com/mmcgrana/gobyexample.svg "Travis CI status")](https://travis-ci.com/mmcgrana/gobyexample)
+
 To build the site you'll need Go and Python installed. Run:
 
 ```console
@@ -34,6 +34,16 @@ To build continuously in a loop:
 $ tools/build-loop
 ```
 
+### Publishing
+
+To upload the site:
+
+```console
+$ gem install aws-sdk
+$ export AWS_ACCESS_KEY_ID=...
+$ export AWS_SECRET_ACCESS_KEY=...
+$ tools/upload
+```
 
 ### License
 
@@ -48,10 +58,13 @@ The Go Gopher is copyright [Renée French](http://reneefrench.blogspot.com/) and
 
 Contributor translations of the Go by Example site are available in:
 
-* [Chinese](http://gobyexample.everyx.in/) by [everyx](https://github.com/everyx)
+* [Chinese](https://gobyexample.xgwang.me/) by [xg-wang](https://github.com/xg-wang/gobyexample)
 * [French](http://le-go-par-l-exemple.keiruaprod.fr) by [keirua](https://github.com/keirua/gobyexample)
 * [Italian](http://gobyexample.it) by the [Go Italian community](https://github.com/golangit/gobyexample-it)
+* [Japanese](http://spinute.org/go-by-example) by [spinute](https://github.com/spinute)
+* [Korean](https://mingrammer.com/gobyexample/) by [mingrammer](https://github.com/mingrammer)
 * [Spanish](http://goconejemplos.com) by the [Go Mexico community](https://github.com/dabit/gobyexample)
+* [Ukrainian](http://gobyexample.com.ua/) by [butuzov](https://github.com/butuzov/gobyexample)
 
 ### Thanks
 

examples.txt

@@ -32,6 +32,7 @@ Range over Channels
 Timers
 Tickers
 Worker Pools
+WaitGroups
 Rate Limiting
 Atomic Counters
 Mutexes
@@ -56,9 +57,15 @@ Base64 Encoding
 Reading Files
 Writing Files
 Line Filters
+File Paths
+Directories
+Temporary Files and Directories
 Command-Line Arguments
 Command-Line Flags
+Command-Line Subcommands
 Environment Variables
+HTTP Clients
+HTTP Servers
 Spawning Processes
 Exec'ing Processes
 Signals

examples/arrays/arrays.hash

@@ -1,2 +1,2 @@
 305975d13d24223181d13f042b290906d86c1a0e
-l-A8eBnwio
+W7NwfDq8Vdw

examples/atomic-counters/atomic-counters.go

@@ -15,7 +15,7 @@ func main() {
 
 	// We'll use an unsigned integer to represent our
 	// (always-positive) counter.
-    var ops uint64 = 0
+	var ops uint64
 
 	// To simulate concurrent updates, we'll start 50
 	// goroutines that each increment the counter about

examples/atomic-counters/atomic-counters.hash

@@ -1,2 +1,2 @@
-ce8821f1f4fd99d554ad6cde52403dd3b69bb70a
-8p48eFFxDZ
+a4190094ea0405b5f2733101beb97939a1d43aee
+KDr9EMMPMgi

examples/base64-encoding/base64-encoding.go

@@ -17,7 +17,7 @@ func main() {
 	// Go supports both standard and URL-compatible
 	// base64. Here's how to encode using the standard
 	// encoder. The encoder requires a `[]byte` so we
-    // cast our `string` to that type.
+	// convert our `string` to that type.
 	sEnc := b64.StdEncoding.EncodeToString([]byte(data))
 	fmt.Println(sEnc)
 

examples/base64-encoding/base64-encoding.hash

@@ -1,2 +1,2 @@
-e57f5be3a796261fb4a55cdb0580a254e14b4930
-t6rFm2x4Yr
+c20da14820b656c867790f2e99bc37140babca8c
+y_QTcqdkvZh

examples/channel-buffering/channel-buffering.hash

@@ -1,2 +1,2 @@
 122140f7ad1bc5cff4fcd7a9e7245b87aaca3ec5
-34PVHwO6Bn
+mPoF-Xi-rip

examples/channel-directions/channel-directions.hash

@@ -1,2 +1,2 @@
 635cc13dfe33123ac188e01e3002d3aa935d765f
-P9Fujfpa1f
+Jnn9_9hC48c

examples/channel-synchronization/channel-synchronization.go

@@ -1,6 +1,8 @@
 // We can use channels to synchronize execution
 // across goroutines. Here's an example of using a
 // blocking receive to wait for a goroutine to finish.
+// When waiting for multiple goroutines to finish,
+// you may prefer to use a [WaitGroup](waitgroups).
 
 package main
 

examples/channel-synchronization/channel-synchronization.hash

@@ -1,2 +1,2 @@
-fe3e2ea1a67d0f95ce4cb18f3e8aa16d416de0ce
-0DfW-1RMqi
+eb022977181884c2ab0f2b69e50311769e67a509
+8lmP8beav0p

examples/channels/channels.hash

@@ -1,2 +1,2 @@
 926212c784ab820648906c96f6ab21afbc161526
-Kd8B0T_JGK
+bRGMAqinovA

examples/closing-channels/closing-channels.hash

@@ -1,2 +1,2 @@
 5205898a520533e46ea24c849848d19ebc2d08a9
-eFZ2SeKswH
+mkz69rVMHs6

examples/closures/closures.go

@@ -14,7 +14,7 @@ import "fmt"
 func intSeq() func() int {
 	i := 0
 	return func() int {
-        i += 1
+		i++
 		return i
 	}
 }

examples/closures/closures.hash

@@ -1,2 +1,2 @@
-2e062d01989caada16c4b22ff6a35cd58e4eb819
-gQtEWkhWyp
+e304df67e760dda93ffe434aca58aea4a6c94f19
+zb93qzV6iN3

examples/collection-functions/collection-functions.go

@@ -21,7 +21,7 @@ package main
 import "strings"
 import "fmt"
 
-// Returns the first index of the target string `t`, or
+// Index returns the first index of the target string `t`, or
 // -1 if no match is found.
 func Index(vs []string, t string) int {
 	for i, v := range vs {
@@ -32,13 +32,13 @@ func Index(vs []string, t string) int {
 	return -1
 }
 
-// Returns `true` if the target string t is in the
+// Include returns `true` if the target string t is in the
 // slice.
 func Include(vs []string, t string) bool {
 	return Index(vs, t) >= 0
 }
 
-// Returns `true` if one of the strings in the slice
+// Any returns `true` if one of the strings in the slice
 // satisfies the predicate `f`.
 func Any(vs []string, f func(string) bool) bool {
 	for _, v := range vs {
@@ -49,7 +49,7 @@ func Any(vs []string, f func(string) bool) bool {
 	return false
 }
 
-// Returns `true` if all of the strings in the slice
+// All returns `true` if all of the strings in the slice
 // satisfy the predicate `f`.
 func All(vs []string, f func(string) bool) bool {
 	for _, v := range vs {
@@ -60,7 +60,7 @@ func All(vs []string, f func(string) bool) bool {
 	return true
 }
 
-// Returns a new slice containing all strings in the
+// Filter returns a new slice containing all strings in the
 // slice that satisfy the predicate `f`.
 func Filter(vs []string, f func(string) bool) []string {
 	vsf := make([]string, 0)
@@ -72,7 +72,7 @@ func Filter(vs []string, f func(string) bool) []string {
 	return vsf
 }
 
-// Returns a new slice containing the results of applying
+// Map returns a new slice containing the results of applying
 // the function `f` to each string in the original slice.
 func Map(vs []string, f func(string) string) []string {
 	vsm := make([]string, len(vs))

examples/collection-functions/collection-functions.hash

@@ -1,2 +1,2 @@
-ed54b3fc0512ccace0f3d0b74975c9bcd2e7a8a2
-3PNdke3Wia
+d961fc0e0074aed46cfd1516efdadea78781af56
+BJB_npWH516

examples/command-line-arguments/command-line-arguments.hash

@@ -1,2 +1,2 @@
 41c970a1ef29ad2a05307e6c783ff52ab80eaccd
-44uyYt_TRl
+6pFdjf800jj

examples/command-line-flags/command-line-flags.hash

@@ -1,2 +1,2 @@
 e2ba0461c090789168c712cc7ed0f66aab09a8c8
-NASEOq2R3n
+klFR5DitrCy

examples/command-line-flags/command-line-flags.sh

@@ -54,6 +54,3 @@ $ ./command-line-flags -wat
 flag provided but not defined: -wat
 Usage of ./command-line-flags:
 ...
-
-# Next we'll look at environment variables, another common
-# way to parameterize programs.

examples/command-line-subcommands/command-line-subcommands.go

@@ -0,0 +1,57 @@
+// Some command-line tools, like the `go` tool or `git`
+// have many *subcommands*, each with its own set of
+// flags. For example, `go build` and `go get` are two
+// different subcommands of the `go` tool.
+// The `flag` package lets us easily define simple
+// subcommands that have their own flags.
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+)
+
+func main() {
+
+	// We declare a subcommand using the `NewFlagSet`
+	// function, and proceed to define new flags specific
+	// for this subcommand.
+	fooCmd := flag.NewFlagSet("foo", flag.ExitOnError)
+	fooEnable := fooCmd.Bool("enable", false, "enable")
+	fooName := fooCmd.String("name", "", "name")
+
+	// For a different subcommand we can define different
+	// supported flags.
+	barCmd := flag.NewFlagSet("bar", flag.ExitOnError)
+	barLevel := barCmd.Int("level", 0, "level")
+
+	// The subcommand is expected as the first argument
+	// to the program.
+	if len(os.Args) < 2 {
+		fmt.Println("expected 'foo' or 'bar' subcommands")
+		os.Exit(1)
+	}
+
+	// Check which subcommand is invoked.
+	switch os.Args[1] {
+
+	// For every subcommand, we parse its own flags and
+	// have access to trailing positional arguments.
+	case "foo":
+		fooCmd.Parse(os.Args[2:])
+		fmt.Println("subcommand 'foo'")
+		fmt.Println("  enable:", *fooEnable)
+		fmt.Println("  name:", *fooName)
+		fmt.Println("  tail:", fooCmd.Args())
+	case "bar":
+		barCmd.Parse(os.Args[2:])
+		fmt.Println("subcommand 'bar'")
+		fmt.Println("  level:", *barLevel)
+		fmt.Println("  tail:", barCmd.Args())
+	default:
+		fmt.Println("expected 'foo' or 'bar' subcommands")
+		os.Exit(1)
+	}
+}

examples/command-line-subcommands/command-line-subcommands.hash

@@ -0,0 +1,2 @@
+5a0ec258e4992e9b93b11d48f2f249092ff3db66
+gtgSAg76N4I

examples/command-line-subcommands/command-line-subcommands.sh

@@ -0,0 +1,24 @@
+$ go build command-line-subcommands.go 
+
+# First invoke the foo subcommand.
+$ ./command-line-subcommands foo -enable -name=joe a1 a2
+subcommand 'foo'
+  enable: true
+  name: joe
+  tail: [a1 a2]
+
+# Now try bar.
+$ ./command-line-subcommands bar -level 8 a1
+subcommand 'bar'
+  level: 8
+  tail: [a1]
+
+# But bar won't accept foo's flags.
+$ ./command-line-subcommands bar -enable a1
+flag provided but not defined: -enable
+Usage of bar:
+  -level int
+    	level
+
+# Next we'll look at environment variables, another common
+# way to parameterize programs.

examples/constants/constants.go

@@ -22,7 +22,7 @@ func main() {
 	fmt.Println(d)
 
 	// A numeric constant has no type until it's given
-    // one, such as by an explicit cast.
+	// one, such as by an explicit conversion.
 	fmt.Println(int64(d))
 
 	// A number can be given a type by using it in a

examples/constants/constants.hash

@@ -1,2 +1,2 @@
-3de4f16f1ed032378268411b2173b95e8000305d
-T5sj0eINnp
+2f2ec3a5ff4eef280199da1908eed261346fb40e
+VhP0f8moZd3

examples/defer/defer.go

@@ -40,5 +40,11 @@ func writeFile(f *os.File) {
 
 func closeFile(f *os.File) {
 	fmt.Println("closing")
-    f.Close()
+	err := f.Close()
+	// It's important to check for errors when closing a
+	// file, even in a deferred function.
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error: %v\n", err)
+		os.Exit(1)
+	}
 }

examples/defer/defer.hash

@@ -1,2 +1,2 @@
-570699fc50a1d39e9d0ad6a4461aef3248b080e1
-9aoHwzHcAo
+fadbe9c05bb42db672316ba19adf3c2189c7b3f5
+OrCaBiCrTKq

examples/directories/directories.go

@@ -0,0 +1,95 @@
+// Go has several useful functions for working with
+// *directories* in the file system.
+
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+)
+
+func check(e error) {
+	if e != nil {
+		panic(e)
+	}
+}
+
+func main() {
+
+	// Create a new sub-directory in the current working
+	// directory.
+	err := os.Mkdir("subdir", 0755)
+	check(err)
+
+	// When creating temporary directories, it's good
+	// practice to `defer` their removal. `os.RemoveAll`
+	// will delete a whole directory tree (similarly to
+	// `rm -rf`).
+	defer os.RemoveAll("subdir")
+
+	// Helper function to create a new empty file.
+	createEmptyFile := func(name string) {
+		d := []byte("")
+		check(ioutil.WriteFile(name, d, 0644))
+	}
+
+	createEmptyFile("subdir/file1")
+
+	// We can create a hierarchy of directories, including
+	// parents with `MkdirAll`. This is similar to the
+	// command-line `mkdir -p`.
+	err = os.MkdirAll("subdir/parent/child", 0755)
+	check(err)
+
+	createEmptyFile("subdir/parent/file2")
+	createEmptyFile("subdir/parent/file3")
+	createEmptyFile("subdir/parent/child/file4")
+
+	// `ReadDir` lists directory contents, returning a
+	// slice of `os.FileInfo` objects.
+	c, err := ioutil.ReadDir("subdir/parent")
+	check(err)
+
+	fmt.Println("Listing subdir/parent")
+	for _, entry := range c {
+		fmt.Println(" ", entry.Name(), entry.IsDir())
+	}
+
+	// `Chdir` lets us change the current working directory,
+	// similarly to `cd`.
+	err = os.Chdir("subdir/parent/child")
+	check(err)
+
+	// Now we'll see the contents of `subdir/parent/child`
+	// when listing the *current* directory.
+	c, err = ioutil.ReadDir(".")
+	check(err)
+
+	fmt.Println("Listing subdir/parent/child")
+	for _, entry := range c {
+		fmt.Println(" ", entry.Name(), entry.IsDir())
+	}
+
+	// `cd` back to where we started.
+	err = os.Chdir("../../..")
+	check(err)
+
+	// We can also visit a directory *recursively*,
+	// including all its sub-directories. `Walk` accepts
+	// a callback function to handle every file or
+	// directory visited.
+	fmt.Println("Visiting subdir")
+	err = filepath.Walk("subdir", visit)
+}
+
+// `visit` is called for every file or directory found
+// recursively by `filepath.Walk`.
+func visit(p string, info os.FileInfo, err error) error {
+	if err != nil {
+		return err
+	}
+	fmt.Println(" ", p, info.IsDir())
+	return nil
+}

examples/directories/directories.hash

@@ -0,0 +1,2 @@
+83f67db91816b4544072d0a4d099111a21c60723
+-7kWq0PmATF

examples/directories/directories.sh

@@ -0,0 +1,15 @@
+$ go run directories.go
+Listing subdir/parent
+  child true
+  file2 false
+  file3 false
+Listing subdir/parent/child
+  file4 false
+Visiting subdir
+  subdir true
+  subdir/file1 false
+  subdir/parent true
+  subdir/parent/child true
+  subdir/parent/child/file4 false
+  subdir/parent/file2 false
+  subdir/parent/file3 false

examples/environment-variables/environment-variables.hash

@@ -1,2 +1,2 @@
 4d0832c5a1ddd4e95474791e8802c15452358214
-kfqLhpmEpw
+CZJ4R_uu6Uu

examples/epoch/epoch.hash

@@ -1,2 +1,2 @@
 61a498229c8878a97d729cfdd215e5f3960f87ac
-GP_zEjhlWk
+eN1Qv2ATB-C

examples/errors/errors.go

@@ -23,7 +23,7 @@ func f1(arg int) (int, error) {
 
 	}
 
-    // A nil value in the error position indicates that
+	// A `nil` value in the error position indicates that
 	// there was no error.
 	return arg + 3, nil
 }

examples/errors/errors.hash

@@ -1,2 +1,2 @@
-07cffb3d4e37162ab7e9e0a192561ddc8042b81a
-BmDQXkPPTk
+210ba0f8196006c0380acaec01655816848ef168
+mP_ZR1qjUvA

examples/execing-processes/execing-processes.hash

@@ -1,2 +1,2 @@
 b527bbb76a42dd4bae541b73a7377b7e83e79905
-neqdJ51KLN
+bf11ADw-2Ho

examples/exit/exit.hash

@@ -1,2 +1,2 @@
 dc0bb3eaafa045d6aa05e88aff39322a1ccf822e
-CDiAh9SXRM
+vDaM0-MGJ_k

examples/file-paths/file-paths.go

@@ -0,0 +1,64 @@
+// The `filepath` package provides functions to parse
+// and construct *file paths* in a way that is portable
+// between operating systems; `dir/file` on Linux vs.
+// `dir\file` on Windows, for example.
+package main
+
+import (
+	"fmt"
+	"path/filepath"
+	"strings"
+)
+
+func main() {
+
+	// `Join` should be used to construct paths in a
+	// portable way. It takes any number of arguments
+	// and constructs a hierarchical path from them.
+	p := filepath.Join("dir1", "dir2", "filename")
+	fmt.Println("p:", p)
+
+	// You should always use `Join` instead of
+	// concatenating `/`s or `\`s manually. In addition
+	// to providing portability, `Join` will also
+	// normalize paths by removing superfluous separators
+	// and directory changes.
+	fmt.Println(filepath.Join("dir1//", "filename"))
+	fmt.Println(filepath.Join("dir1/../dir1", "filename"))
+
+	// `Dir` and `Base` can be used to split a path to the
+	// directory and the file. Alternatively, `Split` will
+	// return both in the same call.
+	fmt.Println("Dir(p):", filepath.Dir(p))
+	fmt.Println("Base(p):", filepath.Base(p))
+
+	// We can check whether a path is absolute.
+	fmt.Println(filepath.IsAbs("dir/file"))
+	fmt.Println(filepath.IsAbs("/dir/file"))
+
+	filename := "config.json"
+
+	// Some file names have extensions following a dot. We
+	// can split the extension out of such names with `Ext`.
+	ext := filepath.Ext(filename)
+	fmt.Println(ext)
+
+	// To find the file's name with the extension removed,
+	// use `strings.TrimSuffix`.
+	fmt.Println(strings.TrimSuffix(filename, ext))
+
+	// `Rel` finds a relative path between a *base* and a
+	// *target*. It returns an error if the target cannot
+	// be made relative to base.
+	rel, err := filepath.Rel("a/b", "a/b/t/file")
+	if err != nil {
+		panic(err)
+	}
+	fmt.Println(rel)
+
+	rel, err = filepath.Rel("a/b", "a/c/t/file")
+	if err != nil {
+		panic(err)
+	}
+	fmt.Println(rel)
+}

examples/file-paths/file-paths.hash

@@ -0,0 +1,2 @@
+1215302b9e59ee9dee21dcd3c47d5f6c672fb058
+QIitbMNiFRx

examples/file-paths/file-paths.sh

@@ -0,0 +1,12 @@
+$ go run file-paths.go
+p: dir1/dir2/filename
+dir1/filename
+dir1/filename
+Dir(p): dir1/dir2
+Base(p): filename
+false
+true
+.json
+config
+t/file
+../c/t/file

examples/for/for.hash

@@ -1,2 +1,2 @@
 33056d6b36f9894fb6359c9cf2ef8725bbdafa19
-KNLLSX4Io_
+lGYfUJwiGfi

examples/functions/functions.hash

@@ -1,2 +1,2 @@
 ae669923c20e5ebf4a7b4b11b8fdf2972accf9e2
-9Nky-Dn49f
+hzGUvK6iJNm

examples/goroutines/goroutines.go

@@ -30,9 +30,8 @@ func main() {
 
 	// Our two function calls are running asynchronously in
 	// separate goroutines now, so execution falls through
-    // to here. This `Scanln` code requires we press a key
+	// to here. This `Scanln` requires we press a key
 	// before the program exits.
-    var input string
-    fmt.Scanln(&input)
+	fmt.Scanln()
 	fmt.Println("done")
 }

examples/goroutines/goroutines.hash

@@ -1,2 +1,2 @@
-a847131d7f112172f9d5509fd3cf31aefb6d710e
-RW_RSAHfj-
+bfdaa0c8104c1257e6fea102fd26d476a3e8c14e
+6Y8t3Yxd1LD

examples/goroutines/goroutines.sh

@@ -1,6 +1,6 @@
 # When we run this program, we see the output of the
 # blocking call first, then the interleaved output of the
-# two gouroutines. This interleaving reflects the
+# two goroutines. This interleaving reflects the
 # goroutines being run concurrently by the Go runtime.
 $ go run goroutines.go
 direct : 0

examples/hello-world/hello-world.hash

@@ -1,2 +1,2 @@
 c98395a44701add5bf84e2f3a63e300fc1bc4bfe
-2C7wwJ6nxG
+mp1ENMU6ZYu

examples/http-clients/http-clients.go

@@ -0,0 +1,38 @@
+// The Go standard library comes with excellent support
+// for HTTP clients and servers in the `net/http`
+// package. In this example we'll use it to issue simple
+// HTTP requests.
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"net/http"
+)
+
+func main() {
+
+	// Issue an HTTP GET request to a server. `http.Get` is a
+	// convenient shortcut around creating an `http.Client`
+	// object and calling its `Get` method; it uses the
+	// `http.DefaultClient` object which has useful default
+	// settings.
+	resp, err := http.Get("http://gobyexample.com")
+	if err != nil {
+		panic(err)
+	}
+	defer resp.Body.Close()
+
+	// Print the HTTP response status.
+	fmt.Println("Response status:", resp.Status)
+
+	// Print the first 5 lines of the response body.
+	scanner := bufio.NewScanner(resp.Body)
+	for i := 0; scanner.Scan() && i < 5; i++ {
+		fmt.Println(scanner.Text())
+	}
+
+	if err := scanner.Err(); err != nil {
+		panic(err)
+	}
+}

examples/http-clients/http-clients.hash

@@ -0,0 +1,2 @@
+ec8fd69aa19e54a7ea05d2a911f09d3a98f0396c
+VxYIifr_UuH

examples/http-clients/http-clients.sh

@@ -0,0 +1,7 @@
+$ go run http-clients.go
+Response status: 200 OK
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="utf-8">
+    <title>Go by Example</title>

examples/http-servers/http-servers.go

@@ -0,0 +1,50 @@
+// Writing a basic HTTP server is easy using the
+// `net/http` package.
+package main
+
+import (
+	"fmt"
+	"net/http"
+)
+
+// A fundamental concept in `net/http` servers is
+// *handlers*. A handler is an object implementing the
+// `http.Handler` interface. A common way to write
+// a handler is by using the `http.HandlerFunc` adapter
+// on functions with the appropriate signature.
+func hello(w http.ResponseWriter, req *http.Request) {
+
+	// Functions serving as handlers take a
+	// `http.ResponseWriter` and a `http.Request` as
+	// arguments. The response writer is used to fill in the
+	// HTTP response. Here our simple response is just
+	// "hello\n".
+	fmt.Fprintf(w, "hello\n")
+}
+
+func headers(w http.ResponseWriter, req *http.Request) {
+
+	// This handler does something a little more
+	// sophisticated by reading all the HTTP request
+	// headers and echoing them into the response body.
+	for name, headers := range req.Header {
+		for _, h := range headers {
+			fmt.Fprintf(w, "%v: %v\n", name, h)
+		}
+	}
+}
+
+func main() {
+
+	// We register our handlers on server routes using the
+	// `http.HandleFunc` convenience function. It sets up
+	// the *default router* in the `net/http` package and
+	// takes a function as an argument.
+	http.HandleFunc("/hello", hello)
+	http.HandleFunc("/headers", headers)
+
+	// Finally, we call the `ListenAndServe` with the port
+	// and a handler. `nil` tells it to use the default
+	// router we've just set up.
+	http.ListenAndServe(":8090", nil)
+}

examples/http-servers/http-servers.hash

@@ -0,0 +1,2 @@
+a4e8d30b7a6f3a6abd96b916d81ce5930bad94f9
+lNuS9ysZmxH

examples/http-servers/http-servers.sh

@@ -0,0 +1,6 @@
+# Run the server in the background.
+$ go run http-servers.go &
+
+# Access the `/hello` route.
+$ curl localhost:8090/hello
+hello

examples/if-else/if-else.hash

@@ -1,2 +1,2 @@
 89b78f3378e1a574ddfd0260a0404a962852eff8
-g-aqMz0Ivf
+p6-WKTqEks4

examples/interfaces/interfaces.hash

@@ -1,2 +1,2 @@
 3547b935d1e0322c0fb696726c27cae53a275e0a
-313UebA3rD
+0EwsqIn3TTi

examples/json/json.go

@@ -10,11 +10,11 @@ import "os"
 
 // We'll use these two structs to demonstrate encoding and
 // decoding of custom types below.
-type Response1 struct {
+type response1 struct {
 	Page   int
 	Fruits []string
 }
-type Response2 struct {
+type response2 struct {
 	Page   int      `json:"page"`
 	Fruits []string `json:"fruits"`
 }
@@ -50,7 +50,7 @@ func main() {
 	// custom data types. It will only include exported
 	// fields in the encoded output and will by default
 	// use those names as the JSON keys.
-    res1D := &Response1{
+	res1D := &response1{
 		Page:   1,
 		Fruits: []string{"apple", "peach", "pear"}}
 	res1B, _ := json.Marshal(res1D)
@@ -58,9 +58,9 @@ func main() {
 
 	// You can use tags on struct field declarations
 	// to customize the encoded JSON key names. Check the
-    // definition of `Response2` above to see an example
+	// definition of `response2` above to see an example
 	// of such tags.
-    res2D := &Response2{
+	res2D := &response2{
 		Page:   1,
 		Fruits: []string{"apple", "peach", "pear"}}
 	res2B, _ := json.Marshal(res2D)
@@ -85,14 +85,14 @@ func main() {
 	fmt.Println(dat)
 
 	// In order to use the values in the decoded map,
-    // we'll need to cast them to their appropriate type.
-    // For example here we cast the value in `num` to
+	// we'll need to convert them to their appropriate type.
+	// For example here we convert the value in `num` to
 	// the expected `float64` type.
 	num := dat["num"].(float64)
 	fmt.Println(num)
 
 	// Accessing nested data requires a series of
-    // casts.
+	// conversions.
 	strs := dat["strs"].([]interface{})
 	str1 := strs[0].(string)
 	fmt.Println(str1)
@@ -103,7 +103,7 @@ func main() {
 	// need for type assertions when accessing the decoded
 	// data.
 	str := `{"page": 1, "fruits": ["apple", "peach"]}`
-    res := Response2{}
+	res := response2{}
 	json.Unmarshal([]byte(str), &res)
 	fmt.Println(res)
 	fmt.Println(res.Fruits[0])

examples/json/json.hash

@@ -1,2 +1,2 @@
-dee52e022a957b97c53fb2d2835653ef507502be
-WxRgpycMaH
+d4dc2281f64061f077d8f1e9687538f41a339b25
+xC6SHbzGBZC

examples/line-filters/line-filters.hash

@@ -1,2 +1,2 @@
 87f4a67edf741979f8ff6da85947aa177547f9ef
-mpYwOHj2ma
+hnaOIaQAjKF

examples/maps/maps.go

@@ -16,7 +16,7 @@ func main() {
 	m["k1"] = 7
 	m["k2"] = 13
 
-    // Printing a map with e.g. `Println` will show all of
+	// Printing a map with e.g. `fmt.Println` will show all of
 	// its key/value pairs.
 	fmt.Println("map:", m)
 

examples/maps/maps.hash

@@ -1,2 +1,2 @@
-2895d63b87f88ab374256c12dd1539cf7b070b77
-E6cGoiKqka
+3e39d07e3f80ecbac558c6fb8baee2a5f914cf97
+U67R66Oab8r

examples/maps/maps.sh

@@ -6,4 +6,4 @@ v1:  7
 len: 2
 map: map[k1:7]
 prs: false
-map: map[foo:1 bar:2]
+map: map[bar:2 foo:1]

examples/methods/methods.hash

@@ -1,2 +1,2 @@
 24cfb9ad45e43c2d49163149bc55925a4e1b3c7a
-254m_9Yjwa
+ffMb0txGnYB

examples/multiple-return-values/multiple-return-values.hash

@@ -1,2 +1,2 @@
 5063ce3d3c70c6bd70f4b709de24bb93d0f24e0c
-chwFmr5dG1
+FZoIB5LXQGZ

examples/mutexes/mutexes.go

@@ -1,6 +1,6 @@
 // In the previous example we saw how to manage simple
 // counter state using [atomic operations](atomic-counters).
-// For more complex state we can use a _[mutex](http://en.wikipedia.org/wiki/Mutual_exclusion)_
+// For more complex state we can use a <em>[mutex](http://en.wikipedia.org/wiki/Mutual_exclusion)</em>
 // to safely access data across multiple goroutines.
 
 package main
@@ -23,8 +23,8 @@ func main() {
 
 	// We'll keep track of how many read and write
 	// operations we do.
-    var readOps uint64 = 0
-    var writeOps uint64 = 0
+	var readOps uint64
+	var writeOps uint64
 
 	// Here we start 100 goroutines to execute repeated
 	// reads against the state, once per millisecond in

examples/mutexes/mutexes.hash

@@ -1,2 +1,2 @@
-e82356cbb37143862b0a9bbc68856f4b272c4918
-a9Wky7k-Bw
+ca257d9594a6219d5803193132e999a32dc8c856
+IRewFKz2OPN

examples/non-blocking-channel-operations/non-blocking-channel-operations.go

@@ -22,7 +22,10 @@ func main() {
 		fmt.Println("no message received")
 	}
 
-    // A non-blocking send works similarly.
+	// A non-blocking send works similarly. Here `msg`
+	// cannot be sent to the `messages` channel, because
+	// the channel has no buffer and there is no receiver.
+	// Therefore the `default` case is selected.
 	msg := "hi"
 	select {
 	case messages <- msg:

examples/non-blocking-channel-operations/non-blocking-channel-operations.hash

@@ -1,2 +1,2 @@
-119ced4df4f79795b163483b6abfd855e76ef577
-M972dltae2
+a6e0a8bb87153c7ed0de4996172f7ad5d89c6814
+n5ttmOsMrrJ

examples/number-parsing/number-parsing.hash

@@ -1,2 +1,2 @@
 0d2155e9863a73c098d44637e92403d7f5e8e965
-N90EppECFk
+NZh4LjhguvN

examples/panic/panic.hash

@@ -1,2 +1,2 @@
 91639bbcfcc6ed088295a9ee6b1c36ab35ae402a
-c86oXzfQOt
+91HXbZZZopt

examples/pointers/pointers.hash

@@ -1,2 +1,2 @@
 85cff3345d2f22b65a5d54eb8f7aa8f508f27887
-KdE4TBbUL2
+fnQkHp4hriG

examples/random-numbers/random-numbers.hash

@@ -1,2 +1,2 @@
 8e97de760147b061dd09939db294c892211b6b80
-ZdFpbahgC1
+jiJaIjxL2sP

examples/range-over-channels/range-over-channels.hash

@@ -1,2 +1,2 @@
 8b5d8a77e84c34771c5b14af014ecef3f88b2a6c
-I63ge2ISDs
+QnARPm-ddFB

examples/range/range.hash

@@ -1,2 +1,2 @@
 ebe328a57f3d34708709ca99d3304af1733592d9
-SkL_AS-1Jd
+JTY1VAUjfBw

examples/rate-limiting/rate-limiting.go

@@ -1,4 +1,4 @@
-// _[Rate limiting](http://en.wikipedia.org/wiki/Rate_limiting)_
+// <em>[Rate limiting](http://en.wikipedia.org/wiki/Rate_limiting)</em>
 // is an important mechanism for controlling resource
 // utilization and maintaining quality of service. Go
 // elegantly supports rate limiting with goroutines,
@@ -24,7 +24,7 @@ func main() {
 	// This `limiter` channel will receive a value
 	// every 200 milliseconds. This is the regulator in
 	// our rate limiting scheme.
-    limiter := time.Tick(time.Millisecond * 200)
+	limiter := time.Tick(200 * time.Millisecond)
 
 	// By blocking on a receive from the `limiter` channel
 	// before serving each request, we limit ourselves to
@@ -49,7 +49,7 @@ func main() {
 	// Every 200 milliseconds we'll try to add a new
 	// value to `burstyLimiter`, up to its limit of 3.
 	go func() {
-        for t := range time.Tick(time.Millisecond * 200) {
+		for t := range time.Tick(200 * time.Millisecond) {
 			burstyLimiter <- t
 		}
 	}()

examples/rate-limiting/rate-limiting.hash

@@ -1,2 +1,2 @@
-d74aebb12f618f22ec776eb5b4de92985104c197
-e7yzIk97-p
+edad78bf3b36ddc9bec30b344b8a72be4de90f3b
+l4uDE-RCDpa

examples/reading-files/reading-files.go

@@ -40,7 +40,7 @@ func main() {
 	b1 := make([]byte, 5)
 	n1, err := f.Read(b1)
 	check(err)
-    fmt.Printf("%d bytes: %s\n", n1, string(b1))
+	fmt.Printf("%d bytes: %s\n", n1, string(b1[:n1]))
 
 	// You can also `Seek` to a known location in the file
 	// and `Read` from there.
@@ -49,7 +49,8 @@ func main() {
 	b2 := make([]byte, 2)
 	n2, err := f.Read(b2)
 	check(err)
-    fmt.Printf("%d bytes @ %d: %s\n", n2, o2, string(b2))
+	fmt.Printf("%d bytes @ %d: ", n2, o2)
+	fmt.Printf("%v\n", string(b2[:n2]))
 
 	// The `io` package provides some functions that may
 	// be helpful for file reading. For example, reads
@@ -80,5 +81,4 @@ func main() {
 	// be scheduled immediately after `Open`ing with
 	// `defer`).
 	f.Close()
-
 }

examples/reading-files/reading-files.hash

@@ -1,2 +1,2 @@
-2aa7a2e248065cebfa6f8eece3234b5ffa710273
-2kEKXq-kUV
+463a6f2999a023887af6b23c8f79f24978eb8115
+cocJ6kBH_iZ

examples/recursion/recursion.hash

@@ -1,2 +1,2 @@
 5d1ba6b03a50ccae2a0f46865eb72c587e11857c
-RFn-rf42ap
+4yUp5wLVyiG

examples/regular-expressions/regular-expressions.hash

@@ -1,2 +1,2 @@
 7cde6b9af5cf6c47606001dd54eee468a6c61dbb
-YeSiBTfhFq
+qR5gn2l0AGa

examples/select/select.go

@@ -17,11 +17,11 @@ func main() {
 	// of time, to simulate e.g. blocking RPC operations
 	// executing in concurrent goroutines.
 	go func() {
-        time.Sleep(time.Second * 1)
+		time.Sleep(1 * time.Second)
 		c1 <- "one"
 	}()
 	go func() {
-        time.Sleep(time.Second * 2)
+		time.Sleep(2 * time.Second)
 		c2 <- "two"
 	}()
 

examples/select/select.hash

@@ -1,2 +1,2 @@
-72503557ab54ef765eeba153fe8a3446541dfc5f
-Vco7d8Lmhn
+8d743edffd7de6bf7bccdf4437f45672b6adc75e
+ZdSOPe1Gj13

examples/sha1-hashes/sha1-hashes.hash

@@ -1,2 +1,2 @@
 6a896270e34f2696b881a8fa7e68bfff57dee51f
-YUaWWEeB4U
+1oT-5GBUkLr

examples/signals/signals.hash

@@ -1,2 +1,2 @@
 9720d747e3ab2893df508a70cbb341c90fdd7ca1
-BlkqAtKsxo
+9koJAW1raI5

examples/slices/slices.go

@@ -30,7 +30,7 @@ func main() {
 	// arrays. One is the builtin `append`, which
 	// returns a slice containing one or more new values.
 	// Note that we need to accept a return value from
-    // append as we may get a new slice value.
+	// `append` as we may get a new slice value.
 	s = append(s, "d")
 	s = append(s, "e", "f")
 	fmt.Println("apd:", s)

examples/slices/slices.hash

@@ -1,2 +1,2 @@
-d900c3b1cf2bd96591f7ad7ce7fd9e592ec31139
-dPQErsP6Yc
+c6fa1627841f199dbf901f88580cb97eb92c5530
+Z3_U32sn8RF

examples/sorting-by-functions/sorting-by-functions.go

@@ -10,10 +10,10 @@ import "sort"
 import "fmt"
 
 // In order to sort by a custom function in Go, we need a
-// corresponding type. Here we've created a `ByLength`
+// corresponding type. Here we've created a `byLength`
 // type that is just an alias for the builtin `[]string`
 // type.
-type ByLength []string
+type byLength []string
 
 // We implement `sort.Interface` - `Len`, `Less`, and
 // `Swap` - on our type so we can use the `sort` package's
@@ -22,22 +22,22 @@ type ByLength []string
 // hold the actual custom sorting logic. In our case we
 // want to sort in order of increasing string length, so
 // we use `len(s[i])` and `len(s[j])` here.
-func (s ByLength) Len() int {
+func (s byLength) Len() int {
 	return len(s)
 }
-func (s ByLength) Swap(i, j int) {
+func (s byLength) Swap(i, j int) {
 	s[i], s[j] = s[j], s[i]
 }
-func (s ByLength) Less(i, j int) bool {
+func (s byLength) Less(i, j int) bool {
 	return len(s[i]) < len(s[j])
 }
 
 // With all of this in place, we can now implement our
-// custom sort by casting the original `fruits` slice to
-// `ByLength`, and then use `sort.Sort` on that typed
+// custom sort by converting the original `fruits` slice
+// to `byLength`, and then use `sort.Sort` on that typed
 // slice.
 func main() {
 	fruits := []string{"peach", "banana", "kiwi"}
-    sort.Sort(ByLength(fruits))
+	sort.Sort(byLength(fruits))
 	fmt.Println(fruits)
 }

examples/sorting-by-functions/sorting-by-functions.hash

@@ -1,2 +1,2 @@
-cec0da0bd98abd7f66fcd38122e4405f757161bc
-N6GbEgBffd
+6a04058b564d5741815e523f97f240ee6563cb15
+y3kuCwIFRYK

examples/sorting/sorting.hash

@@ -1,2 +1,2 @@
 4e576421f2bdbd11847c367d223bd30d0e301990
-roQOJXtqAb
+e6hp3Rn-oH6

examples/spawning-processes/spawning-processes.hash

@@ -1,2 +1,2 @@
 0b676b93e41ac5434003c194bc038d5f3ce76bc8
-y6SB6Mf2VQ
+6HRWVK5gPYU

examples/stateful-goroutines/stateful-goroutines.go

@@ -37,14 +37,14 @@ type writeOp struct {
 func main() {
 
 	// As before we'll count how many operations we perform.
-    var readOps uint64 = 0
-    var writeOps uint64 = 0
+	var readOps uint64
+	var writeOps uint64
 
 	// The `reads` and `writes` channels will be used by
 	// other goroutines to issue read and write requests,
 	// respectively.
-    reads := make(chan *readOp)
-    writes := make(chan *writeOp)
+	reads := make(chan readOp)
+	writes := make(chan writeOp)
 
 	// Here is the goroutine that owns the `state`, which
 	// is a map as in the previous example but now private
@@ -76,7 +76,7 @@ func main() {
 	for r := 0; r < 100; r++ {
 		go func() {
 			for {
-                read := &readOp{
+				read := readOp{
 					key:  rand.Intn(5),
 					resp: make(chan int)}
 				reads <- read
@@ -92,7 +92,7 @@ func main() {
 	for w := 0; w < 10; w++ {
 		go func() {
 			for {
-                write := &writeOp{
+				write := writeOp{
 					key:  rand.Intn(5),
 					val:  rand.Intn(100),
 					resp: make(chan bool)}

examples/stateful-goroutines/stateful-goroutines.hash

@@ -1,2 +1,2 @@
-c306add52c0752f0b3099eb669364fc4bdb74be1
-P4SrrlosMp
+956afe7524b492b2e85f8320c70f180c448a764a
+saQTLpdIgp2

examples/string-formatting/string-formatting.hash

@@ -1,2 +1,2 @@
 5f39ae6d8f26d59a688a9a9d7d13a5c1d0f7a08b
-JJAAFGxHVq
+CkBQ3CFpHQ9

examples/string-functions/string-functions.hash

@@ -1,2 +1,2 @@
 17aa523bbd606fa0b624fae44b89812d46330755
-Lf5_Zbg6or
+Vn4D3y4_711

examples/structs/structs.go

@@ -12,6 +12,15 @@ type person struct {
 	age  int
 }
 
+// NewPerson constructs a new person struct with the given name
+func NewPerson(name string) *person {
+	// You can safely return a pointer to local variable
+	// as a local variable will survive the scope of the function.
+	p := person{name: name}
+	p.age = 42
+	return &p
+}
+
 func main() {
 
 	// This syntax creates a new struct.
@@ -26,6 +35,9 @@ func main() {
 	// An `&` prefix yields a pointer to the struct.
 	fmt.Println(&person{name: "Ann", age: 40})
 
+	// It's idiomatic to encapsulate new struct creation in constructor functions
+	fmt.Println(NewPerson("Jon"))
+
 	// Access struct fields with a dot.
 	s := person{name: "Sean", age: 50}
 	fmt.Println(s.name)

examples/structs/structs.hash

@@ -1,2 +1,2 @@
-49cad39331ee5e9fb8d8dad99d3aff7f18a4e6d0
-OMCP5KFC10
+c5caaf1eefaf084d688afb70d2ee5884a4983182
+00Yiw6xuICq

examples/structs/structs.sh

@@ -6,3 +6,4 @@ $ go run structs.go
 Sean
 50
 51
+&{Jon 42}