-- meta level
liftContext : {X Y : Set} {{_ : N.DataSegment X}} {{_ : N.DataSegment Y}} @$\rightarrow$@ N.CodeSegment X Y @$\rightarrow$@ N.CodeSegment Context Context
liftContext {{x}} {{y}} (N.cs f) = N.cs (\c @$\rightarrow$@ N.DataSegment.set y c (f (N.DataSegment.get x c)))

liftMeta : {X Y : Set} {{_ : M.DataSegment X}} {{_ : M.DataSegment Y}} @$\rightarrow$@ N.CodeSegment X Y @$\rightarrow$@ M.CodeSegment X Y
liftMeta (N.cs f) = M.cs f

gotoMeta : {I O : Set} {{_ : N.DataSegment I}} {{_ : N.DataSegment O}} @$\rightarrow$@ M.CodeSegment Meta Meta @$\rightarrow$@ N.CodeSegment I O @$\rightarrow$@ Meta @$\rightarrow$@ Meta
gotoMeta mCode code m = M.exec mCode (record m {next = (liftContext code)})

push : M.CodeSegment Meta Meta
push = M.cs (\m @$\rightarrow$@ M.exec (liftMeta (Meta.next m)) (record m {c' = Context.c (Meta.context m)}))

-- normal level

cs2 : N.CodeSegment ds1 ds1
cs2 = N.cs id

cs1 : N.CodeSegment ds1 ds1
cs1 = N.cs (\d @$\rightarrow$@ N.goto cs2 d)

cs0 : N.CodeSegment ds0 ds1
cs0 = N.cs (\d @$\rightarrow$@ N.goto cs1 (record {c = (ds0.a d) + (ds0.b d)}))

-- meta level (with extended normal)
main : Meta
main = gotoMeta push cs0 (record {context = (record {a = 100 ; b = 50 ; c = 70}) ; c' = 0 ; next = (N.cs id)})
-- record {context = record {a = 100 ; b = 50 ; c = 150} ; c' = 70 ; next = (N.cs id)}