implementation module StdStack

import StdEnv

:: Stack a = ... // maak deze type definitie af (mag ook een synoniem type zijn, maar gebruik dan :== in plaats van =)

Start  = ( "s0 = newStack = ",        s0,'\n'
         , "s1 = push 1 s0 = ",       s1,'\n'
         , "s2 = pushes [2..5] s1 = ",s2,'\n'
         , "s3 = pop s2 = ",          s3,'\n'
         , "s4 = popn 3 s3 = ",       s4,'\n'
         , "s5 = top s4 = ",          s5,'\n'
         , "s6 = topn 3 s2 = ",       s6,'\n'
         , "s7 = elements s2 = ",     s7,'\n'
         )
where
	s0 = newStack
	s1 = push 1 s0
	s2 = pushes [2..5] s1
	s3 = pop s2
	s4 = popn 3 s3
	s5 = top s4
	s6 = topn 3 s2
	s7 = elements s2