active fst 0 Z mark nil active fst s X cons Y Z mark cons Y fst X Z active from X mark cons X from s X active add 0 X mark X active add s X Y mark s add X Y active len nil mark 0 active len cons X Z mark s len Z active cons X1 X2 cons active X1 X2 active fst X1 X2 fst active X1 X2 active fst X1 X2 fst X1 active X2 active from X from active X active add X1 X2 add active X1 X2 active add X1 X2 add X1 active X2 active len X len active X cons mark X1 X2 mark cons X1 X2 fst mark X1 X2 mark fst X1 X2 fst X1 mark X2 mark fst X1 X2 from mark X mark from X add mark X1 X2 mark add X1 X2 add X1 mark X2 mark add X1 X2 len mark X mark len X proper 0 ok 0 proper s X s proper X proper nil ok nil proper cons X1 X2 cons proper X1 proper X2 proper fst X1 X2 fst proper X1 proper X2 proper from X from proper X proper add X1 X2 add proper X1 proper X2 proper len X len proper X s ok X ok s X cons ok X1 ok X2 ok cons X1 X2 fst ok X1 ok X2 ok fst X1 X2 from ok X ok from X add ok X1 ok X2 ok add X1 X2 len ok X ok len X top mark X top proper X top ok X top active X active 1 fst 2 0 0 mark 1 nil 0 s 1 cons 2 from 1 add 2 len 1 proper 1 ok 1 top 1 INNERMOST ./TRS/TRCSR/inn/Ex2_Luc03b_C.trs