Lisp Tutorial

1
Lisp Tutorial

• Click on Xlisp icon you enter the interpreter
• You can now
• Define functions
• Load program files with .lsp extension
• Execute Lisp functions

2

• gt is the lisp prompt
• gt mylist
• Error unbound variable mylist
• gt (mylist)
• Error unbound function mylist
• (setq mylist (a b c d))
• (A B C D)
• gt mylist
• (A B C D)

3

• (car mylist)
• A
• (cdr mylist)
• (B C D)
• (car (cdr mylist)
• waiting
• ) .. Need to complete the balanced parenthesis
• B
• (cdr (car mylist)) ? What will happen
• Error bad argument type - A

4

• gt nil
• nil
• gt t
• t
• gt (atom mylist)
• nil
• gt (listp mylist)
• t
• gt (equal nil mylist)
• nil

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• gt (null cdr mylist)
• Error unbound variable cdr
• gt (null (cdr mylist) )
• nil
• gt (cdddr mylist)
• (D)
• gt (list (car mylist))
• (A)
• gt (list (cdr mylist))
• ((B C D))

6

• gt (list (car mylist) (caddr mylist))
• (A C)
• gt mylist
• (A B C D)
• gt (last mylist) as defined in the interpreter
• (D)
• gt (cond ((null mylist) (print list is empty
  ) ) )
• NIL
• LISP is NOT case sensitive

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• gt (equal A a)
• T
• gt (cond ( (null mylist) (print empty))
• ( t (print not empty) )
• )
• not empty
• not empty
• Action print not empty
• Return not empty

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• gt (cond ( (null mylist) (print empty))
• ( t mylist )
• )
• (A B C D)
• gt (defun second (l ) (cadr l))
• SECOND
• (second mylist)
• B

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• gt (list (second mylist) (car mylist) (cddr
  mylist) )
• (B A (C D))
• Get the last element of a list
• Define this function
• Recursive definition

10

• Define a function to reverse a list