The Little Schemer - Five Rules

The Five Rules

1. The Law of Car

   • The primitive car is defined only for non-empty lists.

2. The Law of Cdr

   • The primitive cdr is defined only for non-empty lists.
   • The cdr of any non-empty list is always another list.

3. The Law of Cons

   • The primitive cons takes two arguments.
   • The second argument to cons must be a list.
   • The result is a list.

4. The Law of Null?

   • The primitive null? is defined only for lists.

5. The Law of Eq?

   • The primitive eq? takes two arguments.
   • Each must be a non-numeric atom.