more intro stuff for ch 7

cookbook/007/intro.rb

@@ -13,3 +13,27 @@ end
 end
 
 1.upto(3) { |x| puts x }
+
+hello = lambda { "Hello" }
+hello.call
+
+log = lambda { |str| puts "[LOG] #{str}" }
+log.call("A test log message.")
+
+{1=>2, 2=>4}.each { |k,v| puts "Key #{k}, value #{v}" }
+
+def times_n(n)
+  lambda { |x| x * n }
+end
+
+times_ten = times_n(10)
+puts times_ten.call(5)
+puts times_ten.call(1.25)
+
+circumference = times_n(2*Math::PI)
+puts circumference.call(10)
+puts circumference.call(3)
+puts [1, 2, 3].collect(&circumference)
+
+ceiling = 50
+puts [1, 10, 49, 50.1, 200].select { |x| x < ceiling }