An Introduction to Functional Programming Through Lambda Calculus

- 81 -def ’1’ = MAKE_CHAR (succ (value ’0’))...def ’9’ = MAKE_CHAR (succ (value ’8’))def ’A’ = MAKE_CHAR sixty_fivedef ’B’ = MAKE_CHAR (succ (value ’A’))...def ’Z’ = MAKE_CHAR (succ (value ’Y’))def ’a’ = MAKE_CHAR ninety_sevendef ’b’ = MAKE_CHAR (succ (value ’a’))...def ’z’ = MAKE_CHAR (succ (value ’y’))Now we can define character ordering:def CHAR_LESS C1 C2 =if and (ischar C1) (ischar C2)then MAKE_BOOL (less (value C1) (value C2))else CHAR_ERRORand conversion from character to number:def ORD C =if ischar Cthen MAKE_NUMB (value C)else CHAR_ERRORand vice-versa:def CHAR N =if isnumb Nthen MAKE_CHAR (value N)else NUMB_ERRORFor example, to find ’A’s numeric equivalent:ORD ’A’ => ... =>MAKE_NUMB (value ’A’) ==MAKE_NUMB (value λs.(s char_type sixty_five)) -> ... ->MAKE_NUMB sixty_five => ... =>λs.(numb_type sixty_five) ==65