typedef unsigned long long word;

typedef struct{
  word type,
       id,
       car,
       cdr;
}cons;

#define cons
#define number
#define double
#define date
#define varchar
#define symbol

/*
oncreate
  type must exist
  id must be unique
  if type=cons then car must exist within ids or be null
  cdr can only have existing id or be null
cant delete
cant update
*/