lambda.rb

# This will work
x = nil

a = lambda { 
  if x.nil?
    "x is nil, as it should be"
  else
    "somehow x = #{x}"
  end
}

b = lambda {
  x = "what what what?"
  "set x in b"
}

puts a.call
puts b.call
puts a.call

# This will raise 'undefined local variable or method `x' for main:Object (NameError)'
x = nil
def a_meth
  if x.nil?
    "x is nil, as it should be"
  else
    "somehow x = #{x}"
  end
end

def b_meth
  x = "what what what?"
  "set x in b"
end

puts a_meth