Memoize

Common_Lisp_STDERR

 
(format t "This is STDOUT.~%")
(format *error-output* "This is STDERR.~%")
 

Shell

 
% sbcl --script stderr.lisp
This is STDOUT.
This is STDERR.
 
% sbcl --script stderr.lisp > STDOUT.txt 2> STDERR.txt
 
% cat STDOUT.txt
This is STDOUT.
 
% cat STDERR.txt
This is STDERR.
 

http://www.cs.cmu.edu/Groups/AI/html/cltl/clm/node183.html