i i i i i i i       ooooo    o        ooooooo   ooooo   ooooo
  I I I I I I I      8     8   8           8     8     o  8    8
  I  \ `+' /  I      8         8           8     8        8    8
   \  `-+-'  /       8         8           8      ooooo   8oooo
    `-__|__-'        8         8           8           8  8
        |            8     o   8           8     o     8  8
  ------+------       ooooo    8oooooo  ooo8ooo   ooooo   8

Welcome to GNU CLISP 2.49 (2010-07-07) <http://clisp.cons.org/>

Copyright (c) Bruno Haible, Michael Stoll 1992, 1993
Copyright (c) Bruno Haible, Marcus Daniels 1994-1997
Copyright (c) Bruno Haible, Pierpaolo Bernardi, Sam Steingold 1998
Copyright (c) Bruno Haible, Sam Steingold 1999-2000
Copyright (c) Sam Steingold, Bruno Haible 2001-2010

Type :h and hit Enter for context help.

[1]> (load "lp.lsp")
;; Loading file lp.lsp ...
;; Loaded file lp.lsp
T
[2]> (trace select)
;; Tracing function SELECT.
(SELECT)
[3]> (select '(a b c) 2)
1. Trace: (SELECT '(A B C) '2)
2. Trace: (SELECT '(B C) '1)
3. Trace: (SELECT '(C) '0)
3. Trace: SELECT ==> C
2. Trace: SELECT ==> C
1. Trace: SELECT ==> C
C
[4]> (select '(a) 0)
1. Trace: (SELECT '(A) '0)
1. Trace: SELECT ==> A
A
[5]> (select '() 2)
1. Trace: (SELECT 'NIL '2)
1. Trace: SELECT ==> NIL
NIL
[6]> (select '(a) 2)
1. Trace: (SELECT '(A) '2)
1. Trace: SELECT ==> NIL
NIL
[7]> (untrace select)
(SELECT)
[8]> (pick '())
NIL
[9]> (pick '(a))
A
[10]> (pick '(a b c))
B
[11]> (pick '(a b c))
A
[12]> (bye)
Bye.