Blocks, Procs, and Lambdas?

• Block: Anonymous piece of code passed to methods.

3.times { puts "Hello" }

• Proc: Saved block that can be reused.

say = Proc.new { puts "Hi" }
say.call

• Lambda: Like a Proc but stricter about arguments.

l = ->(x) { x*x }
puts l.call(5) # 25