;;; ****************************************************************
;;; Answers to Frequently Asked Questions about Lisp ***************
;;; ****************************************************************
;;; Written by Mark Kantrowitz and Barry Margolin
;;; lisp_3.faq
This post contains Part 3 of the Lisp FAQ.
If you think of questions that are appropriate for this FAQ, or would
like to improve an answer, please send email to us at ai+lisp-faq@cs.cmu.edu.
This section contains a list of common pitfalls. Pitfalls are aspects
of Common Lisp which are non-obvious to new programmers and often
seasoned programmers as well.
Common Pitfalls (Part 3):
 [3-0] Why does (READ-FROM-STRING "foobar" :START 3) return FOOBAR
 instead of BAR? 
 [3-1] Why can't it deduce from (READ-FROM-STRING "foobar" :START 3)
 that the intent is to specify the START keyword parameter
 rather than the EOF-ERROR-P and EOF-VALUE optional parameters? 
 [3-2] Why can't I apply #'AND and #'OR?
 [3-3] I used a destructive function (e.g. DELETE, SORT), but it
 didn't seem to work. Why? 
 [3-4] After I NREVERSE a list, it's only one element long. After I
 SORT a list, it's missing things. What happened? 
 [3-5] Why does (READ-LINE) return "" immediately instead of waiting
 for me to type a line? 
 [3-6] I typed a form to the read-eval-print loop, but nothing happened. Why?
 [3-7] DEFMACRO doesn't seem to work.
 When I compile my file, LISP warns me that my macros are undefined
 functions, or complains "Attempt to call <function> which is 
 defined as a macro.
 [3-8] Name conflict errors are driving me crazy! (EXPORT, packages)
 [3-9] Closures don't seem to work properly when referring to the
 iteration variable in DOLIST, DOTIMES, DO and LOOP.
 [3-10] What is the difference between FUNCALL and APPLY?
 [3-11] Miscellaneous things to consider when debugging code.
 [3-12] When is it right to use EVAL?
 [3-13] Why does my program's behavior change each time I use it?
 [3-14] When producing formatted output in Lisp, where should you put the
 newlines (e.g., before or after the line, FRESH-LINE vs TERPRI,
 ~& vs ~% in FORMAT)?
 [3-15] I'm using DO to do some iteration, but it doesn't terminate. 
 [3-16] My program works when interpreted but not when compiled!
Search for \[#\] to get to question number # quickly.

• News Headers
• [3-0] Why does (READ-FROM-STRING "foobar" :START 3) return FOOBAR instead of BAR?
• [3-1] Why can't it deduce from (READ-FROM-STRING "foobar" :START 3) that the intent is to specify the START keyword parameter rather than
• [3-2] Why can't I apply #'AND and #'OR?
• [3-3] I used a destructive function (e.g. DELETE, SORT), but it didn't seem to work. Why?
• [3-4] After I NREVERSE a list, it's only one element long. After I SORT a list, it's missing things. What happened?
• [3-5] Why does (READ-LINE) return "" immediately instead of waiting for me to type a line?
• [3-6] I typed a form to the read-eval-print loop, but nothing happened. Why?
• [3-7] DEFMACRO doesn't seem to work. When I compile my file, LISP warns me that my macros
• [3-8] Name conflict errors are driving me crazy! (EXPORT, packages)
• [3-9] Closures don't seem to work properly when referring to the iteration variable in DOLIST, DOTIMES, DO and LOOP.
• [3-10] What is the difference between FUNCALL and APPLY?
• [3-11] Miscellaneous things to consider when debugging code.
• [3-12] When is it right to use EVAL?
• [3-13] Why does my program's behavior change each time I use it?
• [3-14] When producing formatted output in Lisp, where should you put the newlines (e.g., before or after the line, FRESH-LINE vs TERPRI,
• [3-15] I'm using DO to do some iteration, but it doesn't terminate.
• [3-16] My program works when interpreted but not when compiled!