About lambda:

• Lambda are just like objects.
• It is just like a regular function whose last statement is it's  returns value.
• Syntax for lambda :  lambda = lambda {}

Example1:

l = lambda{"hello"}

puts l.call

Output: hello

Example2:

a = lambda do |s|

      if s == "hello"

        return "hello from ruby"

      else

        return "bye from ruby"

      end

     end

puts a.call("hello")

Output:  hello from ruby

• Lambda is an instance of the Proc class.
• We can use the return statement inside lambda which makes it more flexible.
• Lambda will return values from lambda itself and not from block or proc.
• Lambda does not have any names as though they behave like methods and they are very rarely in use.

About Procs:

• Procs are same as blocks but the only difference between procs and blocks is that we can store proc in a variable which makes it useful for future purpose.
• We can also pass procs as arguments to functions.

Example1:

x = Proc.new do

      puts "hello everyone"

    end

x.call

Output: hello everyone

About Blocks:

• Unlike proc , block can't be stored in a variable.
• Block is not considered as an object.
• Unlike lambda in which we do not have to provide a name to it , in block we provide it with a name.
• If we want to invoke a block , we call it by the same name as that of the block.
• A block is always invoked with the help of the yield statement.

Example1:

block_name{

  statement1

  statement2

  ..........

  ..........

}

Example2:

def example

  puts "This is the first example"

  yield

  puts "You are in the example"

  yield

end

example {"You are in the block example"}

Output:

This is the first example

You are in the block example

You are in the example

You are in the block example