structure ROOT =
struct
structure Integer =
struct
datatype bit = B0 | B1;
datatype int = Pls | Min | Bit of int * bit | Number_of_int of int;
fun pred (Bit (k, B0)) = Bit (pred k, B1)
| pred (Bit (k, B1)) = Bit (k, B0)
| pred Min = Bit (Min, B0)
| pred Pls = Min;
fun succ (Bit (k, B0)) = Bit (k, B1)
| succ (Bit (k, B1)) = Bit (succ k, B0)
| succ Min = Pls
| succ Pls = Bit (Pls, B1);
fun plus_int (Number_of_int v) (Number_of_int w) =
Number_of_int (plus_int v w)
| plus_int k Min = pred k
| plus_int k Pls = k
| plus_int (Bit (k, B1)) (Bit (l, B1)) = Bit (plus_int k (succ l), B0)
| plus_int (Bit (k, B1)) (Bit (l, B0)) = Bit (plus_int k l, B1)
| plus_int (Bit (k, B0)) (Bit (l, b)) = Bit (plus_int k l, b)
| plus_int Min k = pred k
| plus_int Pls k = k;
fun uminus_int (Number_of_int w) = Number_of_int (uminus_int w)
| uminus_int (Bit (k, B0)) = Bit (uminus_int k, B0)
| uminus_int (Bit (k, B1)) = Bit (pred (uminus_int k), B1)
| uminus_int Min = Bit (Pls, B1)
| uminus_int Pls = Pls;
fun times_int (Number_of_int v) (Number_of_int w) =
Number_of_int (times_int v w)
| times_int (Bit (k, B0)) l = Bit (times_int k l, B0)
| times_int (Bit (k, B1)) l = plus_int (Bit (times_int k l, B0)) l
| times_int Min k = uminus_int k
| times_int Pls w = Pls;
end; (*struct Integer*)
structure Codegen =
struct
fun double_inc k =
Integer.plus_int
(Integer.times_int
(Integer.Number_of_int
(Integer.Bit (Integer.Bit (Integer.Pls, Integer.B1), Integer.B0)))
k)
(Integer.Number_of_int (Integer.Bit (Integer.Pls, Integer.B1)));
end; (*struct Codegen*)
end; (*struct ROOT*)