Common Lisp!

1
Common Lisp!

• John Paxton
• Montana State University
• Summer 2003

2
Montana Statistics

• 2001 Population 904,433. In contrast, El
  Salvador has a population of 6,353,681.
• 90.6 White
• 6.2 Native American
• 2.0 Hispanic or Latino
• Bozeman Population 27,509.

3
Montana Statistics

• Land Area 376,980 square kilometers. In
  contrast, El Salvador has 21,040 square
  kilometers.
• Fun fact The greatest recorded 24 hour
  temperature change occurred in Loma, Montana in
  1972. The temperature rose from -49 F to 54 F!

4
Material

• Defining Functions
• Local Variables
• Using Files
• Predicates
• Boolean Operands
• Lisp Representation

5
defun

• (defun add-ten (n)
• ( n 10)
• )
• ADD-TEN
• gt (add-ten 7)
• 17

6
let

• gt (let ((a 1)(b 2))
• ( a b)
• )
• 3
• gt ( a b)
• - EVAL variable A has no value

7
let

• gt (let ((a 1)(b ( a 1)))
• ( a b)
• )
• 3

8
Using Files

• (load file-name.l)
• (load file-name.lsp)
• (compile-file file-name.l)
• (load file-name)

9
Questions

1. Write a function called gringo-dictionary that
   finds the spanish equivalent for an english word
   passed in.
2. Write a function that returns the roots of a
   quadratic equation in a list. For example,
   (roots 1 5 6) might return (-2 -3).

10
Boolean Values

• t any non-empty list
• nil () ()

11
Equality Predicates

• ( 3 4)
• eq (eq (1 2) (1 2)) (setf a (1 2)) (eq
  a a)
• equal (equal (1 2) (1 2))

12
member Predicate

• (member '(1 2) '((1 1)(1 2)(1 3)))
• NIL
• gt (member '(1 2) '((1 1)(1 2)(1 3)) test
  'equal)
• ((1 2) (1 3))

13
Other Predicates

• listp
• atom
• numberp
• symbolp
• null
• endp
• gt, lt, gt, lt

14
Boolean Operators

• and
• or
• not

15
if statement

• (if (gt 2 3) 'bigger)
• NIL
• gt (if (gt 2 3) 'bigger 'not-bigger)
• NOT-BIGGER

16
cond statement

• (cond
• (test1 statement 1 statement n)
• (test2 statement 1 statement m)
• (testk statement 1 .. statement p)
• )

17
cond statement

• (cond
• ((gt temperature 30) 'hot)
• ((gt temperature 25) 'warm)
• (t 'pleasant)
• )

18
case statement

• (case temperature
• (35 hot)
• (34 hot)
• (otherwise pleasant)
• )

19
Questions

1. Write a function called blackjack that receives
   two card names as inputs. If one card is an ace
   and the other is a jack, the function should
   return the message blackjack. For example,
   (blackjack ace jack) would return blackjack.

20
Questions

1. Define a function that shows a practical use of a
   cond statement.
2. Define a function that shows a practical use of a
   case statement.
3. Define a function that shows a practical use of
   nested conditional statements.

21
Underlying Representation

• (1 2 3)

2
3
1
22
Underlying Representation

• (1 (2) 3)

3
1
2
23
Questions

• Draw the representation of (1 (2 3 (4)) 5)
• Draw the representation of (defun add-one (n)
  ( n 1))
• Depict what happens below (setf list1 (2
  3)) (setf list2 (cons 1 list1))

24
Questions

1. Depict what happens below (setf list1 (1
   2)) (setf list2 (3)) (setf list3 (append list1
   list2))
2. Depict what happens below (setf alist (1 2
   3)) (setf (second alist) 4)