gistfile1.rb

##
# Inverts a `Check`, causing it to treat success as failure and failure as
# success.
def !
  p "! called on #{self}"
  p @lambda
  p @lambda.call
  old_lambda = @lambda
  new_lambda = ->{value = old_lambda.call; p value; !value}
  p new_lambda
  p new_lambda.call
  @lambda = new_lambda
  p @lambda
  p @lambda.call
end

output

"! called on #<Speck::Check:0x000001009e6a28>"
#<Proc:0x000001009e6a50@/Users/elliottcable/Code/speck/lib/speck/core_ext/check_mixins.rb:40 (lambda)>
false
#<Proc:0x000001009e6a50@/Users/elliottcable/Code/speck/lib/speck/core_ext/check_mixins.rb:40 (lambda)>
false
#<Proc:0x000001009e6a50@/Users/elliottcable/Code/speck/lib/speck/core_ext/check_mixins.rb:40 (lambda)>
false
false