pushSingleLinkedStack : Meta -> Meta
pushSingleLinkedStack m = M.exec (liftMeta n) (record m {stack = (push s e) })
  where
    n = Meta.nextCS m
    s = Meta.stack  m
    e = Context.element (Meta.context m)
    push : SingleLinkedStack A -> Maybe A -> SingleLinkedStack A
    push s nothing  = s
    push s (just x) = record {top = just (cons x (top s))}

popSingleLinkedStack : Meta -> Meta
popSingleLinkedStack m = M.exec (liftMeta n) (record m {stack = (st m) ; context = record con {element = (elem m)}})
  where
    n = Meta.nextCS m
    con  = Meta.context m
    elem : Meta -> Maybe A
    elem record {stack = record { top = (just (cons x _)) }} = just x
    elem record {stack = record { top = nothing           }} = nothing
    st : Meta -> SingleLinkedStack A
    st record {stack = record { top = (just (cons _ s)) }} = record {top = s}
    st record {stack = record { top = nothing           }} = record {top = nothing}


pushSingleLinkedStackCS : M.CodeSegment Meta Meta
pushSingleLinkedStackCS = M.cs pushSingleLinkedStack

popSingleLinkedStackCS : M.CodeSegment Meta Meta
popSingleLinkedStackCS = M.cs popSingleLinkedStack