\x -> x 1



?1 1



?3 1



f 1 2



\x -> x



?1



f



f 1 2



2



g 0



\x -> g x



g ?1



5



3



g2



f 32



g2 23



3.14



succ zero



?1



zeroF



dec (succF zeroF)



dec zeroF



\x -> dec x



dec ?1



g3 ?3 0



g (g2 ?1 0)



succ (succ zero)



zero



dec2 0 err



succ err



\x -> dec (dec x)