Adding a new example: recover

With thanks to @LaryBattle for the discussion in #46 and
@kilaka for the discussion in #344.

Fixes #46
Closes #344

examples/recover/recover.go

@@ -0,0 +1,41 @@
+// Go makes it possible to _recover_ from a panic, by
+// using the `recover` built-in function. A `recover` can
+// stop a `panic` from aborting the program and let it
+// continue with execution instead.
+
+// An example of where this can be useful: a server
+// wouldn't want to crash if one of the client connections
+// exhibits a critical error. Instead, the server would
+// want to close that connection and continue serving
+// other clients. In fact, this is what Go's `net/http`
+// does by default for HTTP servers.
+
+package main
+
+import "fmt"
+
+// This function panics.
+func mayPanic() {
+	panic("a problem")
+}
+
+func main() {
+	// `recover` must be called within a deferred function.
+	// When the enclosing function panics, the defer will
+	// activate and a `recover` call within it will catch
+	// the panic.
+	defer func() {
+		if r := recover(); r != nil {
+			// The return value of `recover` is the error raised in
+			// the call to `panic`.
+			fmt.Println("Recovered. Error:\n", r)
+		}
+	}()
+
+	mayPanic()
+
+	// This code will not run, because `mayPanic` panics.
+	// The execution of `main` stops at the point of the
+	// panic and resumes in the deferred closure.
+	fmt.Println("After mayPanic()")
+}

examples/recover/recover.hash

@@ -0,0 +1,2 @@
+053ecbddb4f4a1d881aa40086de99da4e78b9990
+Sk-SVdofEIZ

examples/recover/recover.sh

@@ -0,0 +1,2 @@
+Recovered. Error:
+ a problem