guile/test-suite/tests/srfi-1.test

;;;; srfi-1.test --- Test suite for Guile's SRFI-1 functions. -*- scheme -*-
;;;;
;;;; Copyright 2003-2006, 2008-2011, 2014, 2020 Free Software Foundation, Inc.
;;;;
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
;;;; License as published by the Free Software Foundation; either
;;;; version 3 of the License, or (at your option) any later version.
;;;; 
;;;; This library is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;;;; Lesser General Public License for more details.
;;;; 
;;;; You should have received a copy of the GNU Lesser General Public
;;;; License along with this library; if not, write to the Free Software
;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

(define-module (test-srfi-1)
  #:use-module (test-suite lib)
  #:use-module (ice-9 copy-tree)
  #:use-module (srfi srfi-1))


(define (ref-delete x lst . proc)
  "Reference implemenation of srfi-1 `delete'."
  (set! proc (if (null? proc) equal? (car proc)))
  (do ((ret '())
       (lst lst (cdr lst)))
      ((null? lst)
       (reverse! ret))
    (if (not (proc x (car lst)))
	(set! ret (cons (car lst) ret)))))

(define (ref-delete-duplicates lst . proc)
  "Reference implemenation of srfi-1 `delete-duplicates'."
  (set! proc (if (null? proc) equal? (car proc)))
  (if (null? lst)
      '()
      (do ((keep '()))
	  ((null? lst)
	   (reverse! keep))
	(let ((elem (car lst)))
	  (set! keep (cons elem keep))
	  (set! lst  (ref-delete elem lst proc))))))


;;
;; alist-copy
;;

(with-test-prefix "alist-copy"

  ;; return a list which is the pairs making up alist A, the spine and cells
  (define (alist-pairs a)
    (let more ((a a)
	       (result a))
      (if (pair? a)
	  (more (cdr a) (cons a result))
	  result)))

  ;; return a list of the elements common to lists X and Y, compared with eq?
  (define (common-elements x y)
    (if (null? x)
	'()
	(if (memq (car x) y)
	    (cons (car x) (common-elements (cdr x) y))
	    (common-elements (cdr x) y))))

  ;; validate an alist-copy of OLD to NEW
  ;; lists must be equal, and must comprise new pairs
  (define (valid-alist-copy? old new)
    (and (equal? old new)
	 (null? (common-elements old new))))

  (pass-if-exception "too few args" exception:wrong-num-args
    (alist-copy))
    
  (pass-if-exception "too many args" exception:wrong-num-args
    (alist-copy '() '()))
    
  (let ((old '()))
    (pass-if old (valid-alist-copy? old (alist-copy old))))

  (let ((old '((1 . 2))))
    (pass-if old (valid-alist-copy? old (alist-copy old))))

  (let ((old '((1 . 2) (3 . 4))))
    (pass-if old (valid-alist-copy? old (alist-copy old))))

  (let ((old '((1 . 2) (3 . 4) (5 . 6))))
    (pass-if old (valid-alist-copy? old (alist-copy old)))))

;;
;; alist-delete
;;

(with-test-prefix "alist-delete"

  (pass-if "equality call arg order"
    (let ((good #f))
      (alist-delete 'k '((ak . 123))
		    (lambda (k ak)
		      (if (and (eq? k 'k) (eq? ak 'ak))
			  (set! good #t))))
      good))

  (pass-if "delete keys greater than 5"
    (equal? '((4 . x) (5 . y))
	    (alist-delete 5 '((4 . x) (5 . y) (6 . z)) <)))

  (pass-if "empty"
    (equal? '() (alist-delete 'x '())))

  (pass-if "(y)"
    (equal? '() (alist-delete 'y '((y . 1)))))

  (pass-if "(n)"
    (equal? '((n . 1)) (alist-delete 'y '((n . 1)))))

  (pass-if "(y y)"
    (equal? '() (alist-delete 'y '((y . 1) (y . 2)))))

  (pass-if "(n y)"
    (equal? '((n . 1)) (alist-delete 'y '((n . 1) (y . 2)))))

  (pass-if "(y n)"
    (equal? '((n . 2)) (alist-delete 'y '((y . 1) (n . 2)))))

  (pass-if "(n n)"
    (equal? '((n . 1) (n . 2)) (alist-delete 'y '((n . 1) (n . 2)))))

  (pass-if "(y y y)"
    (equal? '() (alist-delete 'y '((y . 1) (y . 2) (y . 3)))))

  (pass-if "(n y y)"
    (equal? '((n . 1)) (alist-delete 'y '((n . 1) (y . 2) (y . 3)))))

  (pass-if "(y n y)"
    (equal? '((n . 2)) (alist-delete 'y '((y . 1) (n . 2) (y . 3)))))

  (pass-if "(n n y)"
    (equal? '((n . 1) (n . 2)) (alist-delete 'y '((n . 1) (n . 2) (y . 3)))))

  (pass-if "(y y n)"
    (equal? '( (n . 3)) (alist-delete 'y '((y . 1) (y . 2) (n . 3)))))

  (pass-if "(n y n)"
    (equal? '((n . 1) (n . 3)) (alist-delete 'y '((n . 1) (y . 2) (n . 3)))))

  (pass-if "(y n n)"
    (equal? '((n . 2) (n . 3)) (alist-delete 'y '((y . 1) (n . 2) (n . 3)))))

  (pass-if "(n n n)"
    (equal? '((n . 1) (n . 2) (n . 3)) (alist-delete 'y '((n . 1) (n . 2) (n . 3))))))

;;
;; append-map
;;

(with-test-prefix "append-map"

  (with-test-prefix "one list"

    (pass-if "()"
      (equal? '() (append-map noop '(()))))

    (pass-if "(1)"
      (equal? '(1) (append-map noop '((1)))))

    (pass-if "(1 2)"
      (equal? '(1 2) (append-map noop '((1 2)))))

    (pass-if "() ()"
      (equal? '() (append-map noop '(() ()))))

    (pass-if "() (1)"
      (equal? '(1) (append-map noop '(() (1)))))

    (pass-if "() (1 2)"
      (equal? '(1 2) (append-map noop '(() (1 2)))))

    (pass-if "(1) (2)"
      (equal? '(1 2) (append-map noop '((1) (2)))))

    (pass-if "(1 2) ()"
      (equal? '(1 2) (append-map noop '(() (1 2))))))

  (with-test-prefix "two lists"

    (pass-if "() / 9"
      (equal? '() (append-map noop '(()) '(9))))

    (pass-if "(1) / 9"
      (equal? '(1) (append-map noop '((1)) '(9))))

    (pass-if "() () / 9 9"
      (equal? '() (append-map noop '(() ()) '(9 9))))

    (pass-if "(1) (2) / 9"
      (equal? '(1) (append-map noop '((1) (2)) '(9))))

    (pass-if "(1) (2) / 9 9"
      (equal? '(1 2) (append-map noop '((1) (2)) '(9 9))))))

;;
;; append-reverse
;;

(with-test-prefix "append-reverse"

  ;; return a list which is the cars and cdrs of LST
  (define (list-contents lst)
    (if (null? lst)
	'()
	(cons* (car lst) (cdr lst) (list-contents (cdr lst)))))

  (define (valid-append-reverse revhead tail want)
    (let ((revhead-contents (list-contents revhead))
	  (got              (append-reverse revhead tail)))
      (and (equal? got want)
	   ;; revhead unchanged
	   (equal? revhead-contents (list-contents revhead)))))

  (pass-if-exception "too few args (0)" exception:wrong-num-args
    (append-reverse))

  (pass-if-exception "too few args (1)" exception:wrong-num-args
    (append-reverse '(x)))

  (pass-if-exception "too many args (3)" exception:wrong-num-args
    (append-reverse '() '() #f))

  (pass-if (valid-append-reverse '() '()      '()))
  (pass-if (valid-append-reverse '() '(1 2 3) '(1 2 3)))

  (pass-if (valid-append-reverse '(1) '()    '(1)))
  (pass-if (valid-append-reverse '(1) '(2)   '(1 2)))
  (pass-if (valid-append-reverse '(1) '(2 3) '(1 2 3)))

  (pass-if (valid-append-reverse '(1 2) '()    '(2 1)))
  (pass-if (valid-append-reverse '(1 2) '(3)   '(2 1 3)))
  (pass-if (valid-append-reverse '(1 2) '(3 4) '(2 1 3 4)))

  (pass-if (valid-append-reverse '(1 2 3) '()    '(3 2 1)))
  (pass-if (valid-append-reverse '(1 2 3) '(4)   '(3 2 1 4)))
  (pass-if (valid-append-reverse '(1 2 3) '(4 5) '(3 2 1 4 5))))

;;
;; append-reverse!
;;

(with-test-prefix "append-reverse!"

  (pass-if-exception "too few args (0)" exception:wrong-num-args
    (append-reverse!))

  (pass-if-exception "too few args (1)" exception:wrong-num-args
    (append-reverse! '(x)))

  (pass-if-exception "too many args (3)" exception:wrong-num-args
    (append-reverse! '() '() #f))

  (pass-if (equal? '()      (append-reverse! '() '())))
  (pass-if (equal? '(1 2 3) (append-reverse! '() '(1 2 3))))

  (pass-if (equal? '(1)     (append-reverse! '(1) '())))
  (pass-if (equal? '(1 2)   (append-reverse! '(1) '(2))))
  (pass-if (equal? '(1 2 3) (append-reverse! '(1) '(2 3))))

  (pass-if (equal? '(2 1)     (append-reverse! '(1 2) '())))
  (pass-if (equal? '(2 1 3)   (append-reverse! '(1 2) '(3))))
  (pass-if (equal? '(2 1 3 4) (append-reverse! '(1 2) '(3 4))))

  (pass-if (equal? '(3 2 1)     (append-reverse! '(1 2 3) '())))
  (pass-if (equal? '(3 2 1 4)   (append-reverse! '(1 2 3) '(4))))
  (pass-if (equal? '(3 2 1 4 5) (append-reverse! '(1 2 3) '(4 5)))))

;;
;; assoc
;;

(with-test-prefix "assoc"

  (pass-if "not found"
    (let ((alist '((a . 1)
		   (b . 2)
		   (c . 3))))
      (eqv? #f (assoc 'z alist))))

  (pass-if "found"
    (let ((alist '((a . 1)
		   (b . 2)
		   (c . 3))))
      (eqv? (second alist) (assoc 'b alist))))

  ;; this was wrong in guile 1.8.0 (a gremlin newly introduced in the 1.8
  ;; series, 1.6.x and earlier was ok)
  (pass-if "= arg order"
    (let ((alist '((b . 1)))
	  (good  #f))
      (assoc 'a alist (lambda (x y)
			(set! good (and (eq? x 'a)
					(eq? y 'b)))))
      good))

  ;; likewise this one bad in guile 1.8.0
  (pass-if "srfi-1 example <"
    (let ((alist '((1 . a)
		   (5 . b)
		   (6 . c))))
      (eq? (third alist) (assoc 5 alist <)))))

;;
;; break
;;

(with-test-prefix "break"

  (define (test-break lst want-v1 want-v2)
    (call-with-values
	(lambda ()
	  (break negative? lst))
      (lambda (got-v1 got-v2)
	(and (equal? got-v1 want-v1)
	     (equal? got-v2 want-v2)))))

  (pass-if "empty"
    (test-break '() '() '()))

  (pass-if "y"
    (test-break '(1) '(1) '()))

  (pass-if "n"
    (test-break '(-1) '() '(-1)))

  (pass-if "yy"
    (test-break '(1 2) '(1 2) '()))

  (pass-if "ny"
    (test-break '(-1 1) '() '(-1 1)))

  (pass-if "yn"
    (test-break '(1 -1) '(1) '(-1)))

  (pass-if "nn"
    (test-break '(-1 -2) '() '(-1 -2)))

  (pass-if "yyy"
    (test-break '(1 2 3) '(1 2 3) '()))

  (pass-if "nyy"
    (test-break '(-1 1 2) '() '(-1 1 2)))

  (pass-if "yny"
    (test-break '(1 -1 2) '(1) '(-1 2)))

  (pass-if "nny"
    (test-break '(-1 -2 1) '() '(-1 -2 1)))

  (pass-if "yyn"
    (test-break '(1 2 -1) '(1 2) '(-1)))

  (pass-if "nyn"
    (test-break '(-1 1 -2) '() '(-1 1 -2)))

  (pass-if "ynn"
    (test-break '(1 -1 -2) '(1) '(-1 -2)))

  (pass-if "nnn"
    (test-break '(-1 -2 -3) '() '(-1 -2 -3))))

;;
;; break!
;;

(with-test-prefix "break!"

  (define (test-break! lst want-v1 want-v2)
    (call-with-values
	(lambda ()
	  (break! negative? lst))
      (lambda (got-v1 got-v2)
	(and (equal? got-v1 want-v1)
	     (equal? got-v2 want-v2)))))

  (pass-if "empty"
    (test-break! '() '() '()))

  (pass-if "y"
    (test-break! (list 1) '(1) '()))

  (pass-if "n"
    (test-break! (list -1) '() '(-1)))

  (pass-if "yy"
    (test-break! (list 1 2) '(1 2) '()))

  (pass-if "ny"
    (test-break! (list -1 1) '() '(-1 1)))

  (pass-if "yn"
    (test-break! (list 1 -1) '(1) '(-1)))

  (pass-if "nn"
    (test-break! (list -1 -2) '() '(-1 -2)))

  (pass-if "yyy"
    (test-break! (list 1 2 3) '(1 2 3) '()))

  (pass-if "nyy"
    (test-break! (list -1 1 2) '() '(-1 1 2)))

  (pass-if "yny"
    (test-break! (list 1 -1 2) '(1) '(-1 2)))

  (pass-if "nny"
    (test-break! (list -1 -2 1) '() '(-1 -2 1)))

  (pass-if "yyn"
    (test-break! (list 1 2 -1) '(1 2) '(-1)))

  (pass-if "nyn"
    (test-break! (list -1 1 -2) '() '(-1 1 -2)))

  (pass-if "ynn"
    (test-break! (list 1 -1 -2) '(1) '(-1 -2)))

  (pass-if "nnn"
    (test-break! (list -1 -2 -3) '() '(-1 -2 -3))))

;;
;; car+cdr
;;

(with-test-prefix "car+cdr"

  (pass-if "(1 . 2)"
    (call-with-values
	(lambda ()
	  (car+cdr '(1 . 2)))
      (lambda (x y)
	(and (eqv? x 1)
	     (eqv? y 2))))))

;;
;; concatenate and concatenate!
;;

(let ()	
  (define (common-tests concatenate-proc unmodified?)
    (define (try lstlst want)
      (let ((lstlst-copy (copy-tree lstlst))
	    (got         (concatenate-proc lstlst)))
	(if unmodified?
	    (if (not (equal? lstlst lstlst-copy))
		(error "input lists modified")))
	(equal? got want)))
    
    (pass-if-exception "too few args" exception:wrong-num-args
      (concatenate-proc))
    
    (pass-if-exception "too many args" exception:wrong-num-args
      (concatenate-proc '() '()))

    (pass-if-exception "number" exception:wrong-type-arg
      (concatenate-proc 123))

    (pass-if-exception "vector" exception:wrong-type-arg
      (concatenate-proc #(1 2 3)))
    
    (pass-if "no lists"
      (try '() '()))
    
    (pass-if (try '((1))       '(1)))
    (pass-if (try '((1 2))     '(1 2)))
    (pass-if (try '(() (1))    '(1)))
    (pass-if (try '(() () (1)) '(1)))
    
    (pass-if (try '((1) (2)) '(1 2)))
    (pass-if (try '(() (1 2)) '(1 2)))
    
    (pass-if (try '((1) 2)           '(1 . 2)))
    (pass-if (try '((1) (2) 3)       '(1 2 . 3)))
    (pass-if (try '((1) (2) (3 . 4)) '(1 2 3 . 4)))
    )
  
  (with-test-prefix "concatenate"
    (common-tests concatenate #t))
  
  (with-test-prefix "concatenate!"
    (common-tests concatenate! #f)))

;;
;; count
;;

(with-test-prefix "count"
  (pass-if-exception "no args" exception:wrong-num-args
    (count))

  (pass-if-exception "one arg" exception:wrong-num-args
    (count noop))

  (with-test-prefix "one list"
    (define (or1 x)
      x)

    (pass-if "empty list" (= 0 (count or1 '())))

    (pass-if-exception "pred arg count 0" exception:wrong-num-args
      (count (lambda () x) '(1 2 3)))
    (pass-if-exception "pred arg count 2" exception:wrong-num-args
      (count (lambda (x y) x) '(1 2 3)))

    (pass-if-exception "improper 1" exception:wrong-type-arg
      (count or1 1))
    (pass-if-exception "improper 2" exception:wrong-type-arg
      (count or1 '(1 . 2)))
    (pass-if-exception "improper 3" exception:wrong-type-arg
      (count or1 '(1 2 . 3)))

    (pass-if (= 0 (count or1 '(#f))))
    (pass-if (= 1 (count or1 '(#t))))

    (pass-if (= 0 (count or1 '(#f #f))))
    (pass-if (= 1 (count or1 '(#f #t))))
    (pass-if (= 1 (count or1 '(#t #f))))
    (pass-if (= 2 (count or1 '(#t #t))))

    (pass-if (= 0 (count or1 '(#f #f #f))))
    (pass-if (= 1 (count or1 '(#f #f #t))))
    (pass-if (= 1 (count or1 '(#t #f #f))))
    (pass-if (= 2 (count or1 '(#t #f #t))))
    (pass-if (= 3 (count or1 '(#t #t #t)))))

  (with-test-prefix "two lists"
    (define (or2 x y)
      (or x y))

    (pass-if "arg order"
      (= 1 (count (lambda (x y)
		    (and (= 1 x)
			 (= 2 y)))
		  '(1) '(2))))

    (pass-if "empty lists" (= 0 (count or2 '() '())))

    (pass-if-exception "pred arg count 0" exception:wrong-num-args
      (count (lambda () #t) '(1 2 3) '(1 2 3)))
    (pass-if-exception "pred arg count 1" exception:wrong-num-args
      (count (lambda (x) x) '(1 2 3) '(1 2 3)))
    (pass-if-exception "pred arg count 3" exception:wrong-num-args
      (count (lambda (x y z) x) '(1 2 3) '(1 2 3)))

    (pass-if-exception "improper first 1" exception:wrong-type-arg
      (count or2 1 '(1 2 3)))
    (pass-if-exception "improper first 2" exception:wrong-type-arg
      (count or2 '(1 . 2) '(1 2 3)))
    (pass-if-exception "improper first 3" exception:wrong-type-arg
      (count or2 '(1 2 . 3) '(1 2 3)))

    (pass-if-exception "improper second 1" exception:wrong-type-arg
      (count or2 '(1 2 3) 1))
    (pass-if-exception "improper second 2" exception:wrong-type-arg
      (count or2 '(1 2 3) '(1 . 2)))
    (pass-if-exception "improper second 3" exception:wrong-type-arg
      (count or2 '(1 2 3) '(1 2 . 3)))

    (pass-if (= 0 (count or2 '(#f) '(#f))))
    (pass-if (= 1 (count or2 '(#t) '(#f))))
    (pass-if (= 1 (count or2 '(#f) '(#t))))

    (pass-if (= 0 (count or2 '(#f #f) '(#f #f))))
    (pass-if (= 1 (count or2 '(#t #f) '(#t #f))))
    (pass-if (= 2 (count or2 '(#t #t) '(#f #f))))
    (pass-if (= 2 (count or2 '(#t #f) '(#f #t))))

    (with-test-prefix "stop shortest"
      (pass-if (= 2 (count or2 '(#t #f #t) '(#f #t))))
      (pass-if (= 2 (count or2 '(#t #f #t #t) '(#f #t))))
      (pass-if (= 2 (count or2 '(#t #f) '(#f #t #t))))
      (pass-if (= 2 (count or2 '(#t #f) '(#f #t #t #t))))))

  (with-test-prefix "three lists"
    (define (or3 x y z)
      (or x y z))

    (pass-if "arg order"
      (= 1 (count (lambda (x y z)
		    (and (= 1 x)
			 (= 2 y)
			 (= 3 z)))
		  '(1) '(2) '(3))))

    (pass-if "empty lists" (= 0 (count or3 '() '() '())))

    ;; currently bad pred argument gives wrong-num-args when 3 or more
    ;; lists, as opposed to wrong-type-arg for 1 or 2 lists
    (pass-if-exception "pred arg count 0" exception:wrong-num-args
      (count (lambda () #t) '(1 2 3) '(1 2 3) '(1 2 3)))
    (pass-if-exception "pred arg count 2" exception:wrong-num-args
      (count (lambda (x y) x) '(1 2 3) '(1 2 3)'(1 2 3) ))
    (pass-if-exception "pred arg count 4" exception:wrong-num-args
      (count (lambda (w x y z) x) '(1 2 3) '(1 2 3) '(1 2 3)))

    (pass-if-exception "improper first 1" exception:wrong-type-arg
      (count or3 1 '(1 2 3) '(1 2 3)))
    (pass-if-exception "improper first 2" exception:wrong-type-arg
      (count or3 '(1 . 2) '(1 2 3) '(1 2 3)))
    (pass-if-exception "improper first 3" exception:wrong-type-arg
      (count or3 '(1 2 . 3) '(1 2 3) '(1 2 3)))

    (pass-if-exception "improper second 1" exception:wrong-type-arg
      (count or3 '(1 2 3) 1 '(1 2 3)))
    (pass-if-exception "improper second 2" exception:wrong-type-arg
      (count or3 '(1 2 3) '(1 . 2) '(1 2 3)))
    (pass-if-exception "improper second 3" exception:wrong-type-arg
      (count or3 '(1 2 3) '(1 2 . 3) '(1 2 3)))

    (pass-if-exception "improper third 1" exception:wrong-type-arg
      (count or3 '(1 2 3) '(1 2 3) 1))
    (pass-if-exception "improper third 2" exception:wrong-type-arg
      (count or3 '(1 2 3) '(1 2 3) '(1 . 2)))
    (pass-if-exception "improper third 3" exception:wrong-type-arg
      (count or3 '(1 2 3) '(1 2 3) '(1 2 . 3)))

    (pass-if (= 0 (count or3 '(#f) '(#f) '(#f))))
    (pass-if (= 1 (count or3 '(#t) '(#f) '(#f))))
    (pass-if (= 1 (count or3 '(#f) '(#t) '(#f))))
    (pass-if (= 1 (count or3 '(#f) '(#f) '(#t))))

    (pass-if (= 0 (count or3 '(#f #f) '(#f #f) '(#f #f))))

    (pass-if (= 1 (count or3 '(#t #f) '(#f #f) '(#f #f))))
    (pass-if (= 1 (count or3 '(#f #t) '(#f #f) '(#f #f))))
    (pass-if (= 1 (count or3 '(#f #f) '(#t #f) '(#f #f))))
    (pass-if (= 1 (count or3 '(#f #f) '(#f #t) '(#f #f))))
    (pass-if (= 1 (count or3 '(#f #f) '(#f #f) '(#t #f))))
    (pass-if (= 1 (count or3 '(#f #f) '(#f #f) '(#f #t))))

    (pass-if (= 2 (count or3 '(#t #t) '(#f #f) '(#f #f))))
    (pass-if (= 2 (count or3 '(#f #f) '(#t #t) '(#f #f))))
    (pass-if (= 2 (count or3 '(#f #f) '(#f #f) '(#t #t))))
    (pass-if (= 2 (count or3 '(#f #f) '(#t #f) '(#f #t))))

    (with-test-prefix "stop shortest"
      (pass-if (= 0 (count or3 '() '(#t #t #t) '(#t #t))))
      (pass-if (= 0 (count or3 '(#t #t #t) '() '(#t #t))))
      (pass-if (= 0 (count or3 '(#t #t #t) '(#t #t) '())))

      (pass-if (= 1 (count or3 '(#t) '(#t #t #t) '(#t #t))))
      (pass-if (= 1 (count or3 '(#t #t #t) '(#t) '(#t #t))))
      (pass-if (= 1 (count or3 '(#t #t #t) '(#t #t) '(#t)))))

    (pass-if "apply list unchanged"
      (let ((lst (list (list 1 2) (list 3 4) (list 5 6))))
	(and (equal? 2 (apply count or3 lst))
	     ;; lst unmodified
	     (equal? '((1 2) (3 4) (5 6)) lst))))))

;;
;; delete and delete!
;;

(let ()	
  ;; Call (PROC lst) for all lists of length up to 6, with all combinations
  ;; of elements to be retained or deleted.  Elements to retain are numbers,
  ;; 0 upwards.  Elements to be deleted are #f.
  (define (test-lists proc)
    (do ((n 0 (1+ n)))
	((>= n 6))
      (do ((limit (ash 1 n))
	   (i 0 (1+ i)))
	  ((>= i limit))
	(let ((lst '()))
	  (do ((bit 0 (1+ bit)))
	      ((>= bit n))
	    (set! lst  (cons (if (logbit? bit i) bit #f) lst)))
	  (proc lst)))))
  
  (define (common-tests delete-proc)
    (pass-if-exception "too few args" exception:wrong-num-args
      (delete-proc 0))
    
    (pass-if-exception "too many args" exception:wrong-num-args
      (delete-proc 0 '() equal? 99))
    
    (pass-if "empty"
      (eq? '() (delete-proc 0 '() equal?)))
    
    (pass-if "equal?"
      (equal? '((1) (3))
	      (delete-proc '(2) '((1) (2) (3)) equal?)))
    
    (pass-if "eq?"
      (equal? '((1) (2) (3))
	      (delete-proc '(2) '((1) (2) (3)) eq?)))
    
    (pass-if "called arg order"
      (equal? '(1 2 3)
	      (delete-proc 3 '(1 2 3 4 5) <))))
  
  (with-test-prefix "delete"
    (common-tests delete)
    
    (test-lists
     (lambda (lst)
       (let ((lst-copy (list-copy lst)))
	 (with-test-prefix lst-copy
	   (pass-if "result"
	     (equal? (delete     #f lst equal?)
		     (ref-delete #f lst equal?)))
	   (pass-if "non-destructive"
	     (equal? lst-copy lst)))))))  
  
  (with-test-prefix "delete!"
    (common-tests delete!)
    
    (test-lists
     (lambda (lst)
       (pass-if lst
	 (equal? (delete!    #f lst)
		 (ref-delete #f lst)))))))

;;
;; delete-duplicates and delete-duplicates!
;;

(let ()	
  ;; Call (PROC lst) for all lists of length 1 <= n <= 4, with all
  ;; combinations of numbers 1 to n in the elements
  (define (test-lists proc)
    (do ((n 1 (1+ n)))
	((> n 4))
      (do ((limit (integer-expt n n))
	   (i 0 (1+ i)))
	  ((>= i limit))
	(let ((lst '()))
	  (do ((j 0 (1+ j))
	       (rem i (quotient rem n)))
	      ((>= j n))
	    (set! lst (cons (remainder rem n) lst)))
	  (proc lst)))))

  (define (common-tests delete-duplicates-proc)
    (pass-if-exception "too few args" exception:wrong-num-args
      (delete-duplicates-proc))
    
    (pass-if-exception "too many args" exception:wrong-num-args
      (delete-duplicates-proc '() equal? 99))
    
    (pass-if "empty"
      (eq? '() (delete-duplicates-proc '())))
    
    (pass-if "equal? (the default)"
      (equal? '((2))
	      (delete-duplicates-proc '((2) (2) (2)))))
    
    (pass-if "eq?"
      (equal? '((2) (2) (2))
	      (delete-duplicates-proc '((2) (2) (2)) eq?)))

    (pass-if "called arg order"
      (let ((ok #t))
	(delete-duplicates-proc '(1 2 3 4 5)
				(lambda (x y)
				  (if (> x y)
				      (set! ok #f))
				  #f))
	ok)))
  
  (with-test-prefix "delete-duplicates"
    (common-tests delete-duplicates)
    
    (test-lists
     (lambda (lst)
       (let ((lst-copy (list-copy lst)))
	 (with-test-prefix lst-copy
	   (pass-if "result"
	     (equal? (delete-duplicates     lst)
		     (ref-delete-duplicates lst)))
	   (pass-if "non-destructive"
	     (equal? lst-copy lst)))))))  
  
  (with-test-prefix "delete-duplicates!"
    (common-tests delete-duplicates!)
    
    (test-lists
     (lambda (lst)
       (pass-if lst
	 (equal? (delete-duplicates!    lst)
		 (ref-delete-duplicates lst)))))))

;;
;; drop
;;

(with-test-prefix "drop"
  
  (pass-if "'() 0"
    (null? (drop '() 0)))
  
  (pass-if "'(a) 0"
    (let ((lst '(a)))
      (eq? lst
	   (drop lst 0))))
  
  (pass-if "'(a b) 0"
    (let ((lst '(a b)))
      (eq? lst
	   (drop lst 0))))
  
  (pass-if "'(a) 1"
    (let ((lst '(a)))
      (eq? (cdr lst)
	   (drop lst 1))))
  
  (pass-if "'(a b) 1"
    (let ((lst '(a b)))
      (eq? (cdr lst)
	   (drop lst 1))))
  
  (pass-if "'(a b) 2"
    (let ((lst '(a b)))
      (eq? (cddr lst)
	   (drop lst 2))))
  
  (pass-if "'(a b c) 1"
    (let ((lst '(a b c)))
      (eq? (cddr lst)
	   (drop lst 2))))
  
  (pass-if "circular '(a) 0"
    (let ((lst (circular-list 'a)))
      (eq? lst
	   (drop lst 0))))
  
  (pass-if "circular '(a) 1"
    (let ((lst (circular-list 'a)))
      (eq? lst
	   (drop lst 1))))
  
  (pass-if "circular '(a) 2"
    (let ((lst (circular-list 'a)))
      (eq? lst
	   (drop lst 1))))
  
  (pass-if "circular '(a b) 1"
    (let ((lst (circular-list 'a)))
      (eq? (cdr lst)
	   (drop lst 0))))
  
  (pass-if "circular '(a b) 2"
    (let ((lst (circular-list 'a)))
      (eq? lst
	   (drop lst 1))))
  
  (pass-if "circular '(a b) 5"
    (let ((lst (circular-list 'a)))
      (eq? (cdr lst)
	   (drop lst 5))))
  
  (pass-if "'(a . b) 1"
    (eq? 'b
	 (drop '(a . b) 1)))
  
  (pass-if "'(a b . c) 1"
    (equal? 'c
	    (drop '(a b . c) 2))))

;;
;; drop-right
;;

(with-test-prefix "drop-right"

  (pass-if-exception "() -1" exception:out-of-range
    (drop-right '() -1))
  (pass-if (equal? '() (drop-right '() 0)))
  (pass-if-exception "() 1" exception:wrong-type-arg
    (drop-right '() 1))

  (pass-if-exception "(1) -1" exception:out-of-range
    (drop-right '(1) -1))
  (pass-if (equal? '(1) (drop-right '(1) 0)))
  (pass-if (equal? '() (drop-right '(1) 1)))
  (pass-if-exception "(1) 2" exception:wrong-type-arg
    (drop-right '(1) 2))

  (pass-if-exception "(4 5) -1" exception:out-of-range
    (drop-right '(4 5) -1))
  (pass-if (equal? '(4 5) (drop-right '(4 5) 0)))
  (pass-if (equal? '(4) (drop-right '(4 5) 1)))
  (pass-if (equal? '() (drop-right '(4 5) 2)))
  (pass-if-exception "(4 5) 3" exception:wrong-type-arg
    (drop-right '(4 5) 3))

  (pass-if-exception "(4 5 6) -1" exception:out-of-range
    (drop-right '(4 5 6) -1))
  (pass-if (equal? '(4 5 6) (drop-right '(4 5 6) 0)))
  (pass-if (equal? '(4 5) (drop-right '(4 5 6) 1)))
  (pass-if (equal? '(4) (drop-right '(4 5 6) 2)))
  (pass-if (equal? '() (drop-right '(4 5 6) 3)))
  (pass-if-exception "(4 5 6) 4" exception:wrong-type-arg
    (drop-right '(4 5 6) 4))

  (pass-if "(a b . c) 0"
    (equal? (drop-right '(a b . c) 0) '(a b)))
  (pass-if "(a b . c) 1"
    (equal? (drop-right '(a b . c) 1) '(a))))

;;
;; drop-right!
;;

(with-test-prefix "drop-right!"

  (pass-if-exception "() -1" exception:out-of-range
    (drop-right! '() -1))
  (pass-if (equal? '() (drop-right! '() 0)))
  (pass-if-exception "() 1" exception:wrong-type-arg
    (drop-right! '() 1))

  (pass-if-exception "(1) -1" exception:out-of-range
    (drop-right! (list 1) -1))
  (pass-if (equal? '(1) (drop-right! (list 1) 0)))
  (pass-if (equal? '() (drop-right! (list 1) 1)))
  (pass-if-exception "(1) 2" exception:wrong-type-arg
    (drop-right! (list 1) 2))

  (pass-if-exception "(4 5) -1" exception:out-of-range
    (drop-right! (list 4 5) -1))
  (pass-if (equal? '(4 5) (drop-right! (list 4 5) 0)))
  (pass-if (equal? '(4) (drop-right! (list 4 5) 1)))
  (pass-if (equal? '() (drop-right! (list 4 5) 2)))
  (pass-if-exception "(4 5) 3" exception:wrong-type-arg
    (drop-right! (list 4 5) 3))

  (pass-if-exception "(4 5 6) -1" exception:out-of-range
    (drop-right! (list 4 5 6) -1))
  (pass-if (equal? '(4 5 6) (drop-right! (list 4 5 6) 0)))
  (pass-if (equal? '(4 5) (drop-right! (list 4 5 6) 1)))
  (pass-if (equal? '(4) (drop-right! (list 4 5 6) 2)))
  (pass-if (equal? '() (drop-right! (list 4 5 6) 3)))
  (pass-if-exception "(4 5 6) 4" exception:wrong-type-arg
    (drop-right! (list 4 5 6) 4)))

;;
;; drop-while
;;

(with-test-prefix "drop-while"
  
  (pass-if (equal? '()      (drop-while odd? '())))
  (pass-if (equal? '()      (drop-while odd? '(1))))
  (pass-if (equal? '()      (drop-while odd? '(1 3))))
  (pass-if (equal? '()      (drop-while odd? '(1 3 5))))

  (pass-if (equal? '(2)     (drop-while odd? '(2))))
  (pass-if (equal? '(2)     (drop-while odd? '(1 2))))
  (pass-if (equal? '(4)     (drop-while odd? '(1 3 4))))

  (pass-if (equal? '(2 1)   (drop-while odd? '(2 1))))
  (pass-if (equal? '(4 3)   (drop-while odd? '(1 4 3))))
  (pass-if (equal? '(4 1 3) (drop-while odd? '(4 1 3)))))

;;
;; eighth
;;

(with-test-prefix "eighth"
  (pass-if-exception "() -1" exception:wrong-type-arg
    (eighth '(a b c d e f g)))
  (pass-if (eq? 'h (eighth '(a b c d e f g h))))
  (pass-if (eq? 'h (eighth '(a b c d e f g h i)))))

;;
;; fifth
;;

(with-test-prefix "fifth"
  (pass-if-exception "() -1" exception:wrong-type-arg
    (fifth '(a b c d)))
  (pass-if (eq? 'e (fifth '(a b c d e))))
  (pass-if (eq? 'e (fifth '(a b c d e f)))))

;;
;; filter-map
;;

(with-test-prefix "filter-map"

  (with-test-prefix "one list"
    (pass-if-exception "'x" exception:wrong-type-arg
      (filter-map noop 'x))

    (pass-if-exception "'(1 . x)" exception:wrong-type-arg
      (filter-map noop '(1 . x)))

    (pass-if "(1)"
      (equal? '(1) (filter-map noop '(1))))

    (pass-if "(#f)"
      (equal? '() (filter-map noop '(#f))))

    (pass-if "(1 2)"
      (equal? '(1 2) (filter-map noop '(1 2))))

    (pass-if "(#f 2)"
      (equal? '(2) (filter-map noop '(#f 2))))

    (pass-if "(#f #f)"
      (equal? '() (filter-map noop '(#f #f))))

    (pass-if "(1 2 3)"
      (equal? '(1 2 3) (filter-map noop '(1 2 3))))

    (pass-if "(#f 2 3)"
      (equal? '(2 3) (filter-map noop '(#f 2 3))))

    (pass-if "(1 #f 3)"
      (equal? '(1 3) (filter-map noop '(1 #f 3))))

    (pass-if "(1 2 #f)"
      (equal? '(1 2) (filter-map noop '(1 2 #f)))))

  (with-test-prefix "two lists"
    (pass-if-exception "'x '(1 2 3)" exception:wrong-type-arg
      (filter-map noop 'x '(1 2 3)))

    (pass-if-exception "'(1 2 3) 'x" exception:wrong-type-arg
      (filter-map noop '(1 2 3) 'x))

    (pass-if-exception "'(1 . x) '(1 2 3)" exception:wrong-type-arg
      (filter-map noop '(1 . x) '(1 2 3)))

    (pass-if-exception "'(1 2 3) '(1 . x)" exception:wrong-type-arg
      (filter-map noop '(1 2 3) '(1 . x)))

    (pass-if "(1 2 3) (4 5 6)"
      (equal? '(5 7 9) (filter-map + '(1 2 3) '(4 5 6))))

    (pass-if "(#f 2 3) (4 5)"
      (equal? '(2) (filter-map noop '(#f 2 3) '(4 5))))

    (pass-if "(4 #f) (1 2 3)"
      (equal? '(4) (filter-map noop '(4 #f) '(1 2 3))))

    (pass-if "() (1 2 3)"
      (equal? '() (filter-map noop '() '(1 2 3))))

    (pass-if "(1 2 3) ()"
      (equal? '() (filter-map noop '(1 2 3) '()))))

  (with-test-prefix "three lists"
    (pass-if-exception "'x '(1 2 3) '(1 2 3)" exception:wrong-type-arg
      (filter-map noop 'x '(1 2 3) '(1 2 3)))

    (pass-if-exception "'(1 2 3) 'x '(1 2 3)" exception:wrong-type-arg
      (filter-map noop '(1 2 3) 'x '(1 2 3)))

    (pass-if-exception "'(1 2 3) '(1 2 3) 'x" exception:wrong-type-arg
      (filter-map noop '(1 2 3) '(1 2 3) 'x))

    (pass-if-exception "'(1 . x) '(1 2 3) '(1 2 3)" exception:wrong-type-arg
      (filter-map noop '(1 . x) '(1 2 3) '(1 2 3)))

    (pass-if-exception "'(1 2 3) '(1 . x) '(1 2 3)" exception:wrong-type-arg
      (filter-map noop '(1 2 3) '(1 . x) '(1 2 3)))

    (pass-if-exception "'(1 2 3) '(1 2 3) '(1 . x)" exception:wrong-type-arg
      (filter-map noop '(1 2 3) '(1 2 3) '(1 . x)))

    (pass-if "(1 2 3) (4 5 6) (7 8 9)"
      (equal? '(12 15 18) (filter-map + '(1 2 3) '(4 5 6) '(7 8 9))))

    (pass-if "(#f 2 3) (4 5) (7 8 9)"
      (equal? '(2) (filter-map noop '(#f 2 3) '(4 5) '(7 8 9))))

    (pass-if "(#f 2 3) (7 8 9) (4 5)"
      (equal? '(2) (filter-map noop '(#f 2 3) '(7 8 9) '(4 5))))

    (pass-if "(4 #f) (1 2 3) (7 8 9)"
      (equal? '(4) (filter-map noop '(4 #f) '(1 2 3) '(7 8 9))))

    (pass-if "apply list unchanged"
      (let ((lst (list (list 1 #f 2) (list 3 4 5) (list 6 7 8))))
	(and (equal? '(1 2) (apply filter-map noop lst))
	     ;; lst unmodified
	     (equal? lst '((1 #f 2) (3 4 5) (6 7 8))))))))
  
;;
;; find
;;

(with-test-prefix "find"
  (pass-if (eqv? #f (find odd? '())))
  (pass-if (eqv? #f (find odd? '(0))))
  (pass-if (eqv? #f (find odd? '(0 2))))
  (pass-if (eqv? 1 (find odd? '(1))))
  (pass-if (eqv? 1 (find odd? '(0 1))))
  (pass-if (eqv? 1 (find odd? '(0 1 2))))
  (pass-if (eqv? 1 (find odd? '(2 0 1))))
  (pass-if (eqv? 1 (find (lambda (x) (= 1 x)) '(2 0 1)))))

;;
;; find-tail
;;

(with-test-prefix "find-tail"
  (pass-if (let ((lst '()))
	     (eq? #f (find-tail odd? lst))))
  (pass-if (let ((lst '(0)))
	     (eq? #f (find-tail odd? lst))))
  (pass-if (let ((lst '(0 2)))
	     (eq? #f (find-tail odd? lst))))
  (pass-if (let ((lst '(1)))
	     (eq? lst (find-tail odd? lst))))
  (pass-if (let ((lst '(1 2)))
	     (eq? lst (find-tail odd? lst))))
  (pass-if (let ((lst '(2 1)))
	     (eq? (cdr lst) (find-tail odd? lst))))
  (pass-if (let ((lst '(2 1 0)))
	     (eq? (cdr lst) (find-tail odd? lst))))
  (pass-if (let ((lst '(2 0 1)))
	     (eq? (cddr lst) (find-tail odd? lst))))
  (pass-if (let ((lst '(2 0 1)))
	     (eq? (cddr lst) (find-tail (lambda (x) (= 1 x)) lst)))))

;;
;; fold
;;

(with-test-prefix "fold"
  (pass-if-exception "no args" exception:wrong-num-args
    (fold))

  (pass-if-exception "one arg" exception:wrong-num-args
    (fold 123))

  (pass-if-exception "two args" exception:wrong-num-args
    (fold 123 noop))

  (with-test-prefix "one list"

    (pass-if "arg order"
      (eq? #t (fold (lambda (x prev)
		      (and (= 1 x)
			   (= 2 prev)))
		    2 '(1))))

    (pass-if "empty list" (= 123 (fold + 123 '())))

    (pass-if-exception "proc arg count 0" exception:wrong-num-args
      (fold (lambda () x) 123 '(1 2 3)))
    (pass-if-exception "proc arg count 1" exception:wrong-num-args
      (fold (lambda (x) x) 123 '(1 2 3)))
    (pass-if-exception "proc arg count 3" exception:wrong-num-args
      (fold (lambda (x y z) x) 123 '(1 2 3)))

    (pass-if-exception "improper 1" exception:wrong-type-arg
      (fold + 123 1))
    (pass-if-exception "improper 2" exception:wrong-type-arg
      (fold + 123 '(1 . 2)))
    (pass-if-exception "improper 3" exception:wrong-type-arg
      (fold + 123 '(1 2 . 3)))

    (pass-if (= 3 (fold + 1 '(2))))
    (pass-if (= 6 (fold + 1 '(2 3))))
    (pass-if (= 10 (fold + 1 '(2 3 4)))))

  (with-test-prefix "two lists"

    (pass-if "arg order"
      (eq? #t (fold (lambda (x y prev)
		      (and (= 1 x)
			   (= 2 y)
			   (= 3 prev)))
		    3 '(1) '(2))))

    (pass-if "empty lists" (= 1 (fold + 1 '() '())))

    ;; currently bad proc argument gives wrong-num-args when 2 or more
    ;; lists, as opposed to wrong-type-arg for 1 list
    (pass-if-exception "proc arg count 2" exception:wrong-num-args
      (fold (lambda (x prev) x) 1 '(1 2 3) '(1 2 3)))
    (pass-if-exception "proc arg count 4" exception:wrong-num-args
      (fold (lambda (x y z prev) x) 1 '(1 2 3) '(1 2 3)))

    (pass-if-exception "improper first 1" exception:wrong-type-arg
      (fold + 1 1 '(1 2 3)))
    (pass-if-exception "improper first 2" exception:wrong-type-arg
      (fold + 1 '(1 . 2) '(1 2 3)))
    (pass-if-exception "improper first 3" exception:wrong-type-arg
      (fold + 1 '(1 2 . 3) '(1 2 3)))

    (pass-if-exception "improper second 1" exception:wrong-type-arg
      (fold + 1 '(1 2 3) 1))
    (pass-if-exception "improper second 2" exception:wrong-type-arg
      (fold + 1 '(1 2 3) '(1 . 2)))
    (pass-if-exception "improper second 3" exception:wrong-type-arg
      (fold + 1 '(1 2 3) '(1 2 . 3)))

    (pass-if (= 6 (fold + 1 '(2) '(3))))
    (pass-if (= 15 (fold + 1 '(2 3) '(4 5))))
    (pass-if (= 28 (fold + 1 '(2 3 4) '(5 6 7))))

    (with-test-prefix "stop shortest"
      (pass-if (= 13 (fold + 1 '(1 2 3) '(4 5))))
      (pass-if (= 13 (fold + 1 '(4 5) '(1 2 3))))
      (pass-if (= 11 (fold + 1 '(3 4) '(1 2 9 9))))
      (pass-if (= 11 (fold + 1 '(1 2 9 9) '(3 4)))))

    (pass-if "apply list unchanged"
      (let ((lst (list (list 1 2) (list 3 4))))
	(and (equal? 11 (apply fold + 1 lst))
	     ;; lst unmodified
	     (equal? '((1 2) (3 4)) lst)))))

  (with-test-prefix "three lists"

    (pass-if "arg order"
      (eq? #t (fold (lambda (x y z prev)
		      (and (= 1 x)
			   (= 2 y)
			   (= 3 z)
			   (= 4 prev)))
		    4 '(1) '(2) '(3))))

    (pass-if "empty lists" (= 1 (fold + 1 '() '() '())))

    (pass-if-exception "proc arg count 3" exception:wrong-num-args
      (fold (lambda (x y prev) x) 1 '(1 2 3) '(1 2 3)'(1 2 3) ))
    (pass-if-exception "proc arg count 5" exception:wrong-num-args
      (fold (lambda (w x y z prev) x) 1 '(1 2 3) '(1 2 3) '(1 2 3)))

    (pass-if-exception "improper first 1" exception:wrong-type-arg
      (fold + 1 1 '(1 2 3) '(1 2 3)))
    (pass-if-exception "improper first 2" exception:wrong-type-arg
      (fold + 1 '(1 . 2) '(1 2 3) '(1 2 3)))
    (pass-if-exception "improper first 3" exception:wrong-type-arg
      (fold + 1 '(1 2 . 3) '(1 2 3) '(1 2 3)))

    (pass-if-exception "improper second 1" exception:wrong-type-arg
      (fold + 1 '(1 2 3) 1 '(1 2 3)))
    (pass-if-exception "improper second 2" exception:wrong-type-arg
      (fold + 1 '(1 2 3) '(1 . 2) '(1 2 3)))
    (pass-if-exception "improper second 3" exception:wrong-type-arg
      (fold + 1 '(1 2 3) '(1 2 . 3) '(1 2 3)))

    (pass-if-exception "improper third 1" exception:wrong-type-arg
      (fold + 1 '(1 2 3) '(1 2 3) 1))
    (pass-if-exception "improper third 2" exception:wrong-type-arg
      (fold + 1 '(1 2 3) '(1 2 3) '(1 . 2)))
    (pass-if-exception "improper third 3" exception:wrong-type-arg
      (fold + 1 '(1 2 3) '(1 2 3) '(1 2 . 3)))

    (pass-if (= 10 (fold + 1 '(2) '(3) '(4))))
    (pass-if (= 28 (fold + 1 '(2 5) '(3 6) '(4 7))))
    (pass-if (= 55 (fold + 1 '(2 5 8) '(3 6 9) '(4 7 10))))

    (with-test-prefix "stop shortest"
      (pass-if (= 28 (fold + 1 '(2 5 9) '(3 6) '(4 7))))
      (pass-if (= 28 (fold + 1 '(2 5) '(3 6 9) '(4 7))))
      (pass-if (= 28 (fold + 1 '(2 5) '(3 6) '(4 7 9)))))

    (pass-if "apply list unchanged"
      (let ((lst (list (list 1 2) (list 3 4) (list 5 6))))
	(and (equal? 22 (apply fold + 1 lst))
	     ;; lst unmodified
	     (equal? '((1 2) (3 4) (5 6)) lst))))))

;;
;; fold-right
;;

(with-test-prefix "fold-right"

  (pass-if "one list"
    (equal? (iota 10)
            (fold-right cons '() (iota 10))))

  (pass-if "two lists"
    (equal? (zip (iota 10) (map integer->char (iota 10)))
            (fold-right (lambda (x y z)
                          (cons (list x y) z))
                        '()
                        (iota 10)
                        (map integer->char (iota 10)))))

  (pass-if "tail-recursive"
    (= 1e6 (fold-right (lambda (x y) (+ 1 y))
                       0
                       (iota 1e6)))))
;;
;; unfold
;;

(with-test-prefix "unfold"

  (pass-if "basic"
    (equal? (iota 10)
            (unfold (lambda (x) (>= x 10))
                    identity
                    1+
                    0)))

  (pass-if "tail-gen"
    (equal? (append (iota 10) '(tail 10))
            (unfold (lambda (x) (>= x 10))
                    identity
                    1+
                    0
                    (lambda (seed) (list 'tail seed)))))

  (pass-if "tail-recursive"
    ;; Bug #30071.
    (pair? (unfold (lambda (x) (>= x 1e6))
                   identity
                   1+
                   0))))

;;
;; length+
;;

(with-test-prefix "length+"
  (pass-if-exception "too few args" exception:wrong-num-args
    (length+))
  (pass-if-exception "too many args" exception:wrong-num-args
    (length+ 123 456))
  (pass-if-exception "not a pair" exception:wrong-type-arg
    (length+ 'x))
  (pass-if-exception "improper list" exception:wrong-type-arg
    (length+ '(x y . z)))
  (pass-if (= 0 (length+ '())))
  (pass-if (= 1 (length+ '(x))))
  (pass-if (= 2 (length+ '(x y))))
  (pass-if (= 3 (length+ '(x y z))))
  (pass-if (not (length+ (circular-list 1))))
  (pass-if (not (length+ (circular-list 1 2))))
  (pass-if (not (length+ (circular-list 1 2 3)))))

;;
;; last
;;

(with-test-prefix "last"

  (pass-if-exception "empty" exception:wrong-type-arg
    (last '()))
  (pass-if "one elem"
    (eqv? 1 (last '(1))))
  (pass-if "two elems"
    (eqv? 2 (last '(1 2))))
  (pass-if "three elems"
    (eqv? 3 (last '(1 2 3))))
  (pass-if "four elems"
    (eqv? 4 (last '(1 2 3 4)))))

;;
;; list=
;;

(with-test-prefix "list="

  (pass-if "no lists"
    (eq? #t (list= eqv?)))

  (with-test-prefix "one list"

    (pass-if "empty"
      (eq? #t (list= eqv? '())))
    (pass-if "one elem"
      (eq? #t (list= eqv? '(1))))
    (pass-if "two elems"
      (eq? #t (list= eqv? '(2)))))

  (with-test-prefix "two lists"

    (pass-if "empty / empty"
      (eq? #t (list= eqv? '() '())))

    (pass-if "one / empty"
      (eq? #f (list= eqv? '(1) '())))

    (pass-if "empty / one"
      (eq? #f (list= eqv? '() '(1))))

    (pass-if "one / one same"
      (eq? #t (list= eqv? '(1) '(1))))

    (pass-if "one / one diff"
      (eq? #f (list= eqv? '(1) '(2))))

    (pass-if "called arg order"
      (let ((good #t))
	(list= (lambda (x y)
		 (set! good (and good (= (1+ x) y)))
		 #t)
	       '(1 3) '(2 4))
	good)))

  (with-test-prefix "three lists"

    (pass-if "empty / empty / empty"
      (eq? #t (list= eqv? '() '() '())))

    (pass-if "one / empty / empty"
      (eq? #f (list= eqv? '(1) '() '())))

    (pass-if "one / one / empty"
      (eq? #f (list= eqv? '(1) '(1) '())))

    (pass-if "one / diff / empty"
      (eq? #f (list= eqv? '(1) '(2) '())))

    (pass-if "one / one / one"
      (eq? #t (list= eqv? '(1) '(1) '(1))))

    (pass-if "two / two / diff"
      (eq? #f (list= eqv? '(1 2) '(1 2) '(1 99))))

    (pass-if "two / two / two"
      (eq? #t (list= eqv? '(1 2) '(1 2) '(1 2))))

    (pass-if "called arg order"
      (let ((good #t))
	(list= (lambda (x y)
		 (set! good (and good (= (1+ x) y)))
		 #t)
	       '(1 4) '(2 5) '(3 6))
	good))))

;;
;; list-copy
;;

(with-test-prefix "list-copy"
  (pass-if (equal? '()          (list-copy '())))
  (pass-if (equal? '(1 2)       (list-copy '(1 2))))
  (pass-if (equal? '(1 2 3)     (list-copy '(1 2 3))))
  (pass-if (equal? '(1 2 3 4)   (list-copy '(1 2 3 4))))
  (pass-if (equal? '(1 2 3 4 5) (list-copy '(1 2 3 4 5))))
  
  ;; improper lists can be copied
  (pass-if (equal? 1              (list-copy 1)))
  (pass-if (equal? '(1 . 2)       (list-copy '(1 . 2))))
  (pass-if (equal? '(1 2 . 3)     (list-copy '(1 2 . 3))))
  (pass-if (equal? '(1 2 3 . 4)   (list-copy '(1 2 3 . 4))))
  (pass-if (equal? '(1 2 3 4 . 5) (list-copy '(1 2 3 4 . 5)))))

;;
;; list-index
;;

(with-test-prefix "list-index"
  (pass-if-exception "no args" exception:wrong-num-args
    (list-index))

  (pass-if-exception "one arg" exception:wrong-num-args
    (list-index noop))

  (with-test-prefix "one list"

    (pass-if "empty list" (eq? #f (list-index symbol? '())))

    (pass-if-exception "pred arg count 0" exception:wrong-num-args
      (list-index (lambda () x) '(1 2 3)))
    (pass-if-exception "pred arg count 2" exception:wrong-num-args
      (list-index (lambda (x y) x) '(1 2 3)))

    (pass-if-exception "improper 1" exception:wrong-type-arg
      (list-index symbol? 1))
    (pass-if-exception "improper 2" exception:wrong-type-arg
      (list-index symbol? '(1 . 2)))
    (pass-if-exception "improper 3" exception:wrong-type-arg
      (list-index symbol? '(1 2 . 3)))

    (pass-if (eqv? #f (list-index symbol? '(1))))
    (pass-if (eqv? 0 (list-index symbol? '(x))))

    (pass-if (eqv? #f (list-index symbol? '(1 2))))
    (pass-if (eqv? 0 (list-index symbol? '(x 1))))
    (pass-if (eqv? 1 (list-index symbol? '(1 x))))

    (pass-if (eqv? #f (list-index symbol? '(1 2 3))))
    (pass-if (eqv? 0 (list-index symbol? '(x 1 2))))
    (pass-if (eqv? 1 (list-index symbol? '(1 x 2))))
    (pass-if (eqv? 2 (list-index symbol? '(1 2 x)))))

  (with-test-prefix "two lists"
    (define (sym1 x y)
      (symbol? x))
    (define (sym2 x y)
      (symbol? y))

    (pass-if "arg order"
      (eqv? 0 (list-index (lambda (x y)
			    (and (= 1 x)
				 (= 2 y)))
			  '(1) '(2))))

    (pass-if "empty lists" (eqv? #f (list-index sym2 '() '())))

    (pass-if-exception "pred arg count 0" exception:wrong-num-args
      (list-index (lambda () #t) '(1 2 3) '(1 2 3)))
    (pass-if-exception "pred arg count 1" exception:wrong-num-args
      (list-index (lambda (x) x) '(1 2 3) '(1 2 3)))
    (pass-if-exception "pred arg count 3" exception:wrong-num-args
      (list-index (lambda (x y z) x) '(1 2 3) '(1 2 3)))

    (pass-if-exception "improper first 1" exception:wrong-type-arg
      (list-index sym2 1 '(1 2 3)))
    (pass-if-exception "improper first 2" exception:wrong-type-arg
      (list-index sym2 '(1 . 2) '(1 2 3)))
    (pass-if-exception "improper first 3" exception:wrong-type-arg
      (list-index sym2 '(1 2 . 3) '(1 2 3)))

    (pass-if-exception "improper second 1" exception:wrong-type-arg
      (list-index sym2 '(1 2 3) 1))
    (pass-if-exception "improper second 2" exception:wrong-type-arg
      (list-index sym2 '(1 2 3) '(1 . 2)))
    (pass-if-exception "improper second 3" exception:wrong-type-arg
      (list-index sym2 '(1 2 3) '(1 2 . 3)))

    (pass-if (eqv? #f (list-index sym2 '(1) '(2))))
    (pass-if (eqv? 0  (list-index sym2 '(1) '(x))))

    (pass-if (eqv? #f (list-index sym2 '(1 2) '(3 4))))
    (pass-if (eqv? 0  (list-index sym2 '(1 2) '(x 3))))
    (pass-if (eqv? 1  (list-index sym2 '(1 2) '(3 x))))

    (pass-if (eqv? #f (list-index sym2 '(1 2 3) '(3 4 5))))
    (pass-if (eqv? 0  (list-index sym2 '(1 2 3) '(x 3 4))))
    (pass-if (eqv? 1  (list-index sym2 '(1 2 3) '(3 x 4))))
    (pass-if (eqv? 2  (list-index sym2 '(1 2 3) '(3 4 x))))

    (with-test-prefix "stop shortest"
      (pass-if (eqv? #f (list-index sym1 '(1 2 x) '(4 5))))
      (pass-if (eqv? #f (list-index sym2 '(4 5) '(1 2 x))))
      (pass-if (eqv? #f (list-index sym1 '(3 4) '(1 2 x y))))
      (pass-if (eqv? #f (list-index sym2 '(1 2 x y) '(3 4))))))

  (with-test-prefix "three lists"
    (define (sym1 x y z)
      (symbol? x))
    (define (sym2 x y z)
      (symbol? y))
    (define (sym3 x y z)
      (symbol? z))

    (pass-if "arg order"
      (eqv? 0 (list-index (lambda (x y z)
			    (and (= 1 x)
				 (= 2 y)
				 (= 3 z)))
			  '(1) '(2) '(3))))

    (pass-if "empty lists" (eqv? #f (list-index sym3 '() '() '())))

    ;; currently bad pred argument gives wrong-num-args when 3 or more
    ;; lists, as opposed to wrong-type-arg for 1 or 2 lists
    (pass-if-exception "pred arg count 0" exception:wrong-num-args
      (list-index (lambda () #t) '(1 2 3) '(1 2 3) '(1 2 3)))
    (pass-if-exception "pred arg count 2" exception:wrong-num-args
      (list-index (lambda (x y) x) '(1 2 3) '(1 2 3)'(1 2 3) ))
    (pass-if-exception "pred arg count 4" exception:wrong-num-args
      (list-index (lambda (w x y z) x) '(1 2 3) '(1 2 3) '(1 2 3)))

    (pass-if-exception "improper first 1" exception:wrong-type-arg
      (list-index sym3 1 '(1 2 3) '(1 2 3)))
    (pass-if-exception "improper first 2" exception:wrong-type-arg
      (list-index sym3 '(1 . 2) '(1 2 3) '(1 2 3)))
    (pass-if-exception "improper first 3" exception:wrong-type-arg
      (list-index sym3 '(1 2 . 3) '(1 2 3) '(1 2 3)))

    (pass-if-exception "improper second 1" exception:wrong-type-arg
      (list-index sym3 '(1 2 3) 1 '(1 2 3)))
    (pass-if-exception "improper second 2" exception:wrong-type-arg
      (list-index sym3 '(1 2 3) '(1 . 2) '(1 2 3)))
    (pass-if-exception "improper second 3" exception:wrong-type-arg
      (list-index sym3 '(1 2 3) '(1 2 . 3) '(1 2 3)))

    (pass-if-exception "improper third 1" exception:wrong-type-arg
      (list-index sym3 '(1 2 3) '(1 2 3) 1))
    (pass-if-exception "improper third 2" exception:wrong-type-arg
      (list-index sym3 '(1 2 3) '(1 2 3) '(1 . 2)))
    (pass-if-exception "improper third 3" exception:wrong-type-arg
      (list-index sym3 '(1 2 3) '(1 2 3) '(1 2 . 3)))

    (pass-if (eqv? #f (list-index sym3 '(#f) '(#f) '(#f))))
    (pass-if (eqv? 0  (list-index sym3 '(#f) '(#f) '(x))))

    (pass-if (eqv? #f (list-index sym3 '(#f #f) '(#f #f) '(#f #f))))
    (pass-if (eqv? 0  (list-index sym3 '(#f #f) '(#f #f) '(x #f))))
    (pass-if (eqv? 1  (list-index sym3 '(#f #f) '(#f #f) '(#f x))))

    (pass-if (eqv? #f (list-index sym3 '(#f #f #f) '(#f #f #f) '(#f #f #f))))
    (pass-if (eqv? 0  (list-index sym3 '(#f #f #f) '(#f #f #f) '(x #f #f))))
    (pass-if (eqv? 1  (list-index sym3 '(#f #f #f) '(#f #f #f) '(#f x #f))))
    (pass-if (eqv? 2  (list-index sym3 '(#f #f #f) '(#f #f #f) '(#f #f x))))

    (with-test-prefix "stop shortest"
      (pass-if (eqv? #f (list-index sym2 '() '(x x x) '(x x))))
      (pass-if (eqv? #f (list-index sym1 '(x x x) '() '(x x))))
      (pass-if (eqv? #f (list-index sym2 '(x x x) '(x x) '())))

      (pass-if (eqv? #f (list-index sym2 '(#t) '(#t x x) '(#t x))))
      (pass-if (eqv? #f (list-index sym1 '(#t x x) '(#t) '(#t x))))
      (pass-if (eqv? #f (list-index sym1 '(#t x x) '(#t x) '(#t)))))

    (pass-if "apply list unchanged"
      (let ((lst (list (list 1 2) (list 3 4) (list 5 6))))
	(and (equal? #f (apply list-index sym3 lst))
	     ;; lst unmodified
	     (equal? '((1 2) (3 4) (5 6)) lst))))))

;;
;; list-tabulate
;;

(with-test-prefix "list-tabulate"

  (pass-if-exception "-1" exception:wrong-type-arg
    (list-tabulate -1 identity))
  (pass-if "0"
    (equal? '() (list-tabulate 0 identity)))
  (pass-if "1"
    (equal? '(0) (list-tabulate 1 identity)))
  (pass-if "2"
    (equal? '(0 1) (list-tabulate 2 identity)))
  (pass-if "3"
    (equal? '(0 1 2) (list-tabulate 3 identity)))
  (pass-if "4"
    (equal? '(0 1 2 3) (list-tabulate 4 identity)))
  (pass-if "string ref proc"
    (equal? '(#\a #\b #\c #\d) (list-tabulate 4
					      (lambda (i)
						(string-ref "abcd" i))))))

;;
;; lset=
;;

(with-test-prefix "lset="

  ;; in guile 1.6.7 and earlier, lset= incorrectly demanded at least one
  ;; list arg
  (pass-if "no args"
    (eq? #t (lset= eq?)))

  (with-test-prefix "one arg"

    (pass-if "()"
      (eq? #t (lset= eqv? '())))

    (pass-if "(1)"
      (eq? #t (lset= eqv? '(1))))

    (pass-if "(1 2)"
      (eq? #t (lset= eqv? '(1 2)))))

  (with-test-prefix "two args"

    (pass-if "() ()"
      (eq? #t (lset= eqv? '() '())))

    (pass-if "(1) (1)"
      (eq? #t (lset= eqv? '(1) '(1))))

    (pass-if "(1) (2)"
      (eq? #f (lset= eqv? '(1) '(2))))

    (pass-if "(1) (1 2)"
      (eq? #f (lset= eqv? '(1) '(1 2))))

    (pass-if "(1 2) (2 1)"
      (eq? #t (lset= eqv? '(1 2) '(2 1))))

    (pass-if "called arg order"
      (let ((good #t))
	(lset= (lambda (x y)
		 (if (not (= x (1- y)))
		     (set! good #f))
		 #t)
	       '(1 1) '(2 2))
	good)))

  (with-test-prefix "three args"

    (pass-if "() () ()"
      (eq? #t (lset= eqv? '() '() '())))

    (pass-if "(1) (1) (1)"
      (eq? #t (lset= eqv? '(1) '(1) '(1))))

    (pass-if "(1) (1) (2)"
      (eq? #f (lset= eqv? '(1) '(1) '(2))))

    (pass-if "(1) (1) (1 2)"
      (eq? #f (lset= eqv? '(1) '(1) '(1 2))))

    (pass-if "(1 2 3) (3 2 1) (1 3 2)"
      (eq? #t (lset= eqv? '(1 2 3) '(3 2 1) '(1 3 2))))

    (pass-if "called arg order"
      (let ((good #t))
	(lset= (lambda (x y)
		 (if (not (= x (1- y)))
		     (set! good #f))
		 #t)
	       '(1 1) '(2 2) '(3 3))
	good))))

;;
;; lset-adjoin
;;

(with-test-prefix "lset-adjoin"

  ;; in guile 1.6.7 and earlier, lset-adjoin didn't actually use the given
  ;; `=' procedure, all comparisons were just with `equal?
  ;;
  (with-test-prefix "case-insensitive ="

    (pass-if "(\"x\") \"X\""
      (equal? '("x") (lset-adjoin string-ci=? '("x") "X"))))

  (pass-if "called arg order"
    (let ((good #f))
      (lset-adjoin (lambda (x y)
		     (set! good (and (= x 1) (= y 2)))
		     (= x y))
		   '(1) 2)
      good))

  (pass-if (equal? '() (lset-adjoin = '())))

  (pass-if (equal? '(1) (lset-adjoin = '() 1)))

  (pass-if (equal? '(1) (lset-adjoin = '() 1 1)))

  (pass-if (equal? '(2 1) (lset-adjoin = '() 1 2)))

  (pass-if (equal? '(3 1 2) (lset-adjoin = '(1 2) 1 2 3 2 1)))

  (pass-if "apply list unchanged"
    (let ((lst (list 1 2)))
      (and (equal? '(2 1 3) (apply lset-adjoin = '(3) lst))
	   ;; lst unmodified
	   (equal? '(1 2) lst))))

  (pass-if "(1 1) 1 1"
    (equal? '(1 1) (lset-adjoin = '(1 1) 1 1)))

  ;; duplicates among args are cast out
  (pass-if "(2) 1 1"
    (equal? '(1 2) (lset-adjoin = '(2) 1 1))))

;;
;; lset-difference
;;

(with-test-prefix "lset-difference"

  (pass-if "called arg order"
    (let ((good #f))
      (lset-difference (lambda (x y)
			 (set! good (and (= x 1) (= y 2)))
			 (= x y))
		       '(1) '(2))
      good)))  

;;
;; lset-difference!
;;

(with-test-prefix "lset-difference!"

  (pass-if-exception "proc - num" exception:wrong-type-arg
    (lset-difference! 123 '(4)))
  (pass-if-exception "proc - list" exception:wrong-type-arg
    (lset-difference! (list 1 2 3) '(4)))

  (pass-if "called arg order"
    (let ((good #f))
      (lset-difference! (lambda (x y)
			  (set! good (and (= x 1) (= y 2)))
			  (= x y))
			(list 1) (list 2))
      good))

  (pass-if (equal? '() (lset-difference! = '())))
  (pass-if (equal? '(1) (lset-difference! = (list 1))))
  (pass-if (equal? '(1 2) (lset-difference! = (list 1 2))))

  (pass-if (equal? '() (lset-difference! = (list ) '(3))))
  (pass-if (equal? '() (lset-difference! = (list 3) '(3))))
  (pass-if (equal? '(1) (lset-difference! = (list 1 3) '(3))))
  (pass-if (equal? '(1) (lset-difference! = (list 3 1) '(3))))
  (pass-if (equal? '(1) (lset-difference! = (list 1 3 3) '(3))))
  (pass-if (equal? '(1) (lset-difference! = (list 3 1 3) '(3))))
  (pass-if (equal? '(1) (lset-difference! = (list 3 3 1) '(3))))

  (pass-if (equal? '(1) (lset-difference! = (list 1 2 3) '(2 3))))
  (pass-if (equal? '(1) (lset-difference! = (list 1 2 3) '(3 2))))
  (pass-if (equal? '(1) (lset-difference! = (list 1 2 3) '(3) '(2))))
  (pass-if (equal? '(1) (lset-difference! = (list 1 2 3) '(2) '(3))))
  (pass-if (equal? '(1) (lset-difference! = (list 1 2 3) '(2) '(2 3))))
  (pass-if (equal? '(1) (lset-difference! = (list 1 2 3) '(2) '(3 2))))

  (pass-if (equal? '(1 2) (lset-difference! = (list 1 2 3) '(3) '(3))))
  (pass-if (equal? '(1 2) (lset-difference! = (list 1 3 2) '(3) '(3))))
  (pass-if (equal? '(1 2) (lset-difference! = (list 3 1 2) '(3) '(3))))

  (pass-if (equal? '(1 2 3) (lset-difference! = (list 1 2 3 4) '(4))))
  (pass-if (equal? '(1 2 3) (lset-difference! = (list 1 2 4 3) '(4))))
  (pass-if (equal? '(1 2 3) (lset-difference! = (list 1 4 2 3) '(4))))
  (pass-if (equal? '(1 2 3) (lset-difference! = (list 4 1 2 3) '(4))))

  (pass-if (equal? '(1 2) (lset-difference! = (list 1 2 3 4) '(4) '(3))))
  (pass-if (equal? '(1 2) (lset-difference! = (list 1 3 2 4) '(4) '(3))))
  (pass-if (equal? '(1 2) (lset-difference! = (list 3 1 2 4) '(4) '(3))))
  (pass-if (equal? '(1 2) (lset-difference! = (list 1 3 4 2) '(4) '(3))))
  (pass-if (equal? '(1 2) (lset-difference! = (list 3 1 4 2) '(4) '(3))))
  (pass-if (equal? '(1 2) (lset-difference! = (list 3 4 1 2) '(4) '(3)))))

;;
;; lset-diff+intersection
;;

(with-test-prefix "lset-diff+intersection"

  (pass-if "called arg order"
    (let ((good #f))
      (lset-diff+intersection (lambda (x y)
				(set! good (and (= x 1) (= y 2)))
				(= x y))
			      '(1) '(2))
      good)))  

;;
;; lset-diff+intersection!
;;

(with-test-prefix "lset-diff+intersection"

  (pass-if "called arg order"
    (let ((good #f))
      (lset-diff+intersection (lambda (x y)
				(set! good (and (= x 1) (= y 2)))
				(= x y))
			      (list 1) (list 2))
      good)))  

;;
;; lset-intersection
;;

(with-test-prefix "lset-intersection"

  (pass-if "called arg order"
    (let ((good #f))
      (lset-intersection (lambda (x y)
			   (set! good (and (= x 1) (= y 2)))
			   (= x y))
			 '(1) '(2))
      good)))  

;;
;; lset-intersection!
;;

(with-test-prefix "lset-intersection"

  (pass-if "called arg order"
    (let ((good #f))
      (lset-intersection (lambda (x y)
			   (set! good (and (= x 1) (= y 2)))
			   (= x y))
			 (list 1) (list 2))
      good)))  

;;
;; lset-union
;;

(with-test-prefix "lset-union"

  (pass-if "no args"
    (eq? '() (lset-union eq?)))

  (pass-if "one arg"
    (equal? '(1 2 3) (lset-union eq? '(1 2 3))))

  (pass-if "'() '()"
    (equal? '() (lset-union eq? '() '())))

  (pass-if "'() '(1 2 3)"
    (equal? '(1 2 3) (lset-union eq? '() '(1 2 3))))

  (pass-if "'(1 2 3) '()"
    (equal? '(1 2 3) (lset-union eq? '(1 2 3) '())))

  (pass-if "'(1 2 3) '(4 3 5)"
    (equal? '(5 4 1 2 3) (lset-union eq? '(1 2 3) '(4 3 5))))

  (pass-if "'(1 2 3) '(4) '(3 5))"
    (equal? '(5 4 1 2 3) (lset-union eq? '(1 2 3) '(4) '(3 5))))

  ;; in guile 1.6.7 and earlier, `=' was called with the arguments the wrong
  ;; way around
  (pass-if "called arg order"
    (let ((good #f))
      (lset-union (lambda (x y)
		    (set! good (and (= x 1) (= y 2)))
		    (= x y))
		  '(1) '(2))
      good)))

;;
;; member
;;

(with-test-prefix "member"

  (pass-if-exception "no args" exception:wrong-num-args
    (member))

  (pass-if-exception "one arg" exception:wrong-num-args
    (member 1))

  (pass-if "1 (1 2 3)"
    (let ((lst '(1 2 3)))
      (eq? lst (member 1 lst))))

  (pass-if "2 (1 2 3)"
    (let ((lst '(1 2 3)))
      (eq? (cdr lst) (member 2 lst))))

  (pass-if "3 (1 2 3)"
    (let ((lst '(1 2 3)))
      (eq? (cddr lst) (member 3 lst))))

  (pass-if "4 (1 2 3)"
    (let ((lst '(1 2 3)))
      (eq? #f (member 4 lst))))

  (pass-if "called arg order"
    (let ((good #f))
      (member 1 '(2) (lambda (x y)
		       (set! good (and (eqv? 1 x)
				       (eqv? 2 y)))))
      good)))

;;
;; ninth
;;

(with-test-prefix "ninth"
  (pass-if-exception "() -1" exception:wrong-type-arg
    (ninth '(a b c d e f g h)))
  (pass-if (eq? 'i (ninth '(a b c d e f g h i))))
  (pass-if (eq? 'i (ninth '(a b c d e f g h i j)))))


;;
;; not-pair?
;;

(with-test-prefix "not-pair?"
  (pass-if "inum"
    (eq? #t (not-pair? 123)))
  (pass-if "pair"
    (eq? #f (not-pair? '(x . y))))
  (pass-if "symbol"
    (eq? #t (not-pair? 'x))))

;;
;; take
;;

(with-test-prefix "take"
  
  (pass-if "'() 0"
    (null? (take '() 0)))
  
  (pass-if "'(a) 0"
    (null? (take '(a) 0)))
  
  (pass-if "'(a b) 0"
    (null? (take '() 0)))
  
  (pass-if "'(a b c) 0"
    (null? (take '() 0)))
  
  (pass-if "'(a) 1"
    (let* ((lst '(a))
	   (got (take lst 1)))
      (and (equal? '(a) got)
	   (not (eq? lst got)))))
  
  (pass-if "'(a b) 1"
    (equal? '(a)
	    (take '(a b) 1)))
  
  (pass-if "'(a b c) 1"
    (equal? '(a)
	    (take '(a b c) 1)))
  
  (pass-if "'(a b) 2"
    (let* ((lst '(a b))
	   (got (take lst 2)))
      (and (equal? '(a b) got)
	   (not (eq? lst got)))))
  
  (pass-if "'(a b c) 2"
    (equal? '(a b)
	    (take '(a b c) 2)))
  
  (pass-if "circular '(a) 0"
    (equal? '()
	    (take (circular-list 'a) 0)))
  
  (pass-if "circular '(a) 1"
    (equal? '(a)
	    (take (circular-list 'a) 1)))
  
  (pass-if "circular '(a) 2"
    (equal? '(a a)
	    (take (circular-list 'a) 2)))
  
  (pass-if "circular '(a b) 5"
    (equal? '(a b a b a)
	    (take (circular-list 'a 'b) 5)))
  
  (pass-if "'(a . b) 1"
    (equal? '(a)
	    (take '(a . b) 1)))
  
  (pass-if "'(a b . c) 1"
    (equal? '(a)
	    (take '(a b . c) 1)))
  
  (pass-if "'(a b . c) 2"
    (equal? '(a b)
	    (take '(a b . c) 2))))

;;
;; take-while
;;

(with-test-prefix "take-while"
  
  (pass-if (equal? '()      (take-while odd? '())))
  (pass-if (equal? '(1)     (take-while odd? '(1))))
  (pass-if (equal? '(1 3)   (take-while odd? '(1 3))))
  (pass-if (equal? '(1 3 5) (take-while odd? '(1 3 5))))

  (pass-if (equal? '()      (take-while odd? '(2))))
  (pass-if (equal? '(1)     (take-while odd? '(1 2))))
  (pass-if (equal? '(1 3)   (take-while odd? '(1 3 4))))

  (pass-if (equal? '()      (take-while odd? '(2 1))))
  (pass-if (equal? '(1)     (take-while odd? '(1 4 3))))
  (pass-if (equal? '()      (take-while odd? '(4 1 3)))))

;;
;; take-while!
;;

(with-test-prefix "take-while!"
  
  (pass-if (equal? '()      (take-while! odd? '())))
  (pass-if (equal? '(1)     (take-while! odd? (list 1))))
  (pass-if (equal? '(1 3)   (take-while! odd? (list 1 3))))
  (pass-if (equal? '(1 3 5) (take-while! odd? (list 1 3 5))))

  (pass-if (equal? '()      (take-while! odd? (list 2))))
  (pass-if (equal? '(1)     (take-while! odd? (list 1 2))))
  (pass-if (equal? '(1 3)   (take-while! odd? (list 1 3 4))))

  (pass-if (equal? '()      (take-while! odd? (list 2 1))))
  (pass-if (equal? '(1)     (take-while! odd? (list 1 4 3))))
  (pass-if (equal? '()      (take-while! odd? (list 4 1 3)))))

;;
;; partition
;;

(define (test-partition pred list kept-good dropped-good)
  (call-with-values (lambda ()
			(partition pred list))
      (lambda (kept dropped)
	(and (equal? kept kept-good)
	     (equal? dropped dropped-good)))))

(with-test-prefix "partition"
		  
  (pass-if "with dropped tail"
    (test-partition even? '(1 2 3 4 5 6 7)
		    '(2 4 6) '(1 3 5 7)))

  (pass-if "with kept tail"
    (test-partition even? '(1 2 3 4 5 6)
		    '(2 4 6) '(1 3 5)))

  (pass-if "with everything dropped"
    (test-partition even? '(1 3 5 7)
		    '() '(1 3 5 7)))

  (pass-if "with everything kept"
    (test-partition even? '(2 4 6)
		    '(2 4 6) '()))

  (pass-if "with empty list"
    (test-partition even? '()
		    '() '()))

  (pass-if "with reasonably long list"
    ;; the old implementation from SRFI-1 reference implementation
    ;; would signal a stack-overflow for a list of only 500 elements!
    (call-with-values (lambda ()
			(partition even?
				   (make-list 10000 1)))
      (lambda (even odd)
	(and (= (length odd) 10000)
	     (= (length even) 0)))))

  (pass-if-exception "with improper list"
    exception:wrong-type-arg
    (partition symbol? '(a b . c))))

;;
;; partition!
;;

(define (test-partition! pred list kept-good dropped-good)
  (call-with-values (lambda ()
			(partition! pred list))
      (lambda (kept dropped)
	(and (equal? kept kept-good)
	     (equal? dropped dropped-good)))))

(with-test-prefix "partition!"

  (pass-if "with dropped tail"
    (test-partition! even? (list 1 2 3 4 5 6 7)
		     '(2 4 6) '(1 3 5 7)))

  (pass-if "with kept tail"
    (test-partition! even? (list 1 2 3 4 5 6)
		     '(2 4 6) '(1 3 5)))

  (pass-if "with everything dropped"
    (test-partition! even? (list 1 3 5 7)
		     '() '(1 3 5 7)))

  (pass-if "with everything kept"
    (test-partition! even? (list 2 4 6)
		     '(2 4 6) '()))

  (pass-if "with empty list"
    (test-partition! even? '()
		     '() '()))

  (pass-if "with reasonably long list"
    ;; the old implementation from SRFI-1 reference implementation
    ;; would signal a stack-overflow for a list of only 500 elements!
    (call-with-values (lambda ()
			(partition! even?
				    (make-list 10000 1)))
      (lambda (even odd)
	(and (= (length odd) 10000)
	     (= (length even) 0)))))

  (pass-if-exception "with improper list"
    exception:wrong-type-arg
    (partition! symbol? (cons* 'a 'b 'c))))

;;
;; reduce
;;

(with-test-prefix "reduce"

  (pass-if "empty"
    (let* ((calls '())
	   (ret   (reduce (lambda (x prev)
			    (set! calls (cons (list x prev) calls))
			    x)
			  1 '())))
      (and (equal? calls '())
	   (equal? ret   1))))

  (pass-if "one elem"
    (let* ((calls '())
	   (ret   (reduce (lambda (x prev)
			    (set! calls (cons (list x prev) calls))
			    x)
			  1 '(2))))
      (and (equal? calls '())
	   (equal? ret   2))))

  (pass-if "two elems"
    (let* ((calls '())
	   (ret   (reduce (lambda (x prev)
			    (set! calls (cons (list x prev) calls))
			    x)
			  1 '(2 3))))
      (and (equal? calls '((3 2)))
	   (equal? ret   3))))

  (pass-if "three elems"
    (let* ((calls '())
	   (ret   (reduce (lambda (x prev)
			    (set! calls (cons (list x prev) calls))
			    x)
			  1 '(2 3 4))))
      (and (equal? calls '((4 3)
			   (3 2)))
	   (equal? ret   4))))

  (pass-if "four elems"
    (let* ((calls '())
	   (ret   (reduce (lambda (x prev)
			    (set! calls (cons (list x prev) calls))
			    x)
			  1 '(2 3 4 5))))
      (and (equal? calls '((5 4)
			   (4 3)
			   (3 2)))
	   (equal? ret   5)))))

;;
;; reduce-right
;;

(with-test-prefix "reduce-right"

  (pass-if "empty"
    (let* ((calls '())
	   (ret   (reduce-right (lambda (x prev)
				  (set! calls (cons (list x prev) calls))
				  x)
				1 '())))
      (and (equal? calls '())
	   (equal? ret   1))))

  (pass-if "one elem"
    (let* ((calls '())
	   (ret   (reduce-right (lambda (x prev)
				  (set! calls (cons (list x prev) calls))
				  x)
				1 '(2))))
      (and (equal? calls '())
	   (equal? ret   2))))

  (pass-if "two elems"
    (let* ((calls '())
	   (ret   (reduce-right (lambda (x prev)
				  (set! calls (cons (list x prev) calls))
				  x)
				1 '(2 3))))
      (and (equal? calls '((2 3)))
	   (equal? ret   2))))

  (pass-if "three elems"
    (let* ((calls '())
	   (ret   (reduce-right (lambda (x prev)
				  (set! calls (cons (list x prev) calls))
				  x)
				1 '(2 3 4))))
      (and (equal? calls '((2 3)
			   (3 4)))
	   (equal? ret   2))))

  (pass-if "four elems"
    (let* ((calls '())
	   (ret   (reduce-right (lambda (x prev)
				  (set! calls (cons (list x prev) calls))
				  x)
				1 '(2 3 4 5))))
      (and (equal? calls '((2 3)
			   (3 4)
			   (4 5)))
	   (equal? ret   2)))))
  
;;
;; remove
;;

(with-test-prefix "remove"

  (pass-if (equal? '() (remove odd? '())))
  (pass-if (equal? '() (remove odd? '(1))))
  (pass-if (equal? '(2) (remove odd? '(2))))

  (pass-if (equal? '() (remove odd? '(1 3))))
  (pass-if (equal? '(2) (remove odd? '(2 3))))
  (pass-if (equal? '(2) (remove odd? '(1 2))))
  (pass-if (equal? '(2 4) (remove odd? '(2 4))))

  (pass-if (equal? '() (remove odd? '(1 3 5))))
  (pass-if (equal? '(2) (remove odd? '(2 3 5))))
  (pass-if (equal? '(2) (remove odd? '(1 2 5))))
  (pass-if (equal? '(2 4) (remove odd? '(2 4 5))))

  (pass-if (equal? '(6) (remove odd? '(1 3 6))))
  (pass-if (equal? '(2 6) (remove odd? '(2 3 6))))
  (pass-if (equal? '(2 6) (remove odd? '(1 2 6))))
  (pass-if (equal? '(2 4 6) (remove odd? '(2 4 6)))))

;;
;; remove!
;;

(with-test-prefix "remove!"

  (pass-if (equal? '() (remove! odd? '())))
  (pass-if (equal? '() (remove! odd? (list 1))))
  (pass-if (equal? '(2) (remove! odd? (list 2))))

  (pass-if (equal? '() (remove! odd? (list 1 3))))
  (pass-if (equal? '(2) (remove! odd? (list 2 3))))
  (pass-if (equal? '(2) (remove! odd? (list 1 2))))
  (pass-if (equal? '(2 4) (remove! odd? (list 2 4))))

  (pass-if (equal? '() (remove! odd? (list 1 3 5))))
  (pass-if (equal? '(2) (remove! odd? (list 2 3 5))))
  (pass-if (equal? '(2) (remove! odd? (list 1 2 5))))
  (pass-if (equal? '(2 4) (remove! odd? (list 2 4 5))))

  (pass-if (equal? '(6) (remove! odd? (list 1 3 6))))
  (pass-if (equal? '(2 6) (remove! odd? (list 2 3 6))))
  (pass-if (equal? '(2 6) (remove! odd? (list 1 2 6))))
  (pass-if (equal? '(2 4 6) (remove! odd? (list 2 4 6)))))

;;
;; seventh
;;

(with-test-prefix "seventh"
  (pass-if-exception "() -1" exception:wrong-type-arg
    (seventh '(a b c d e f)))
  (pass-if (eq? 'g (seventh '(a b c d e f g))))
  (pass-if (eq? 'g (seventh '(a b c d e f g h)))))

;;
;; sixth
;;

(with-test-prefix "sixth"
  (pass-if-exception "() -1" exception:wrong-type-arg
    (sixth '(a b c d e)))
  (pass-if (eq? 'f (sixth '(a b c d e f))))
  (pass-if (eq? 'f (sixth '(a b c d e f g)))))

;;
;; split-at
;;

(with-test-prefix "split-at"

  (define (equal-values? lst thunk)
    (call-with-values thunk
      (lambda got
	(equal? lst got))))

  (pass-if-exception "() -1" exception:out-of-range
    (split-at '() -1))
  (pass-if (equal-values? '(() ())
			  (lambda () (split-at '() 0))))
  (pass-if-exception "() 1" exception:wrong-type-arg
    (split-at '() 1))

  (pass-if-exception "(1) -1" exception:out-of-range
    (split-at '(1) -1))
  (pass-if (equal-values? '(() (1)) (lambda () (split-at '(1) 0))))
  (pass-if (equal-values? '((1) ()) (lambda () (split-at '(1) 1))))
  (pass-if-exception "(1) 2" exception:wrong-type-arg
    (split-at '(1) 2))

  (pass-if-exception "(4 5) -1" exception:out-of-range
    (split-at '(4 5) -1))
  (pass-if (equal-values? '(() (4 5)) (lambda () (split-at '(4 5) 0))))
  (pass-if (equal-values? '((4) (5)) (lambda () (split-at '(4 5) 1))))
  (pass-if (equal-values? '((4 5) ()) (lambda () (split-at '(4 5) 2))))
  (pass-if-exception "(4 5) 3" exception:wrong-type-arg
    (split-at '(4 5) 3))

  (pass-if-exception "(4 5 6) -1" exception:out-of-range
    (split-at '(4 5 6) -1))
  (pass-if (equal-values? '(() (4 5 6)) (lambda () (split-at '(4 5 6) 0))))
  (pass-if (equal-values? '((4) (5 6)) (lambda () (split-at '(4 5 6) 1))))
  (pass-if (equal-values? '((4 5) (6)) (lambda () (split-at '(4 5 6) 2))))
  (pass-if (equal-values? '((4 5 6) ()) (lambda () (split-at '(4 5 6) 3))))
  (pass-if-exception "(4 5 6) 4" exception:wrong-type-arg
    (split-at '(4 5 6) 4)))

;;
;; split-at!
;;

(with-test-prefix "split-at!"

  (define (equal-values? lst thunk)
    (call-with-values thunk
      (lambda got
	(equal? lst got))))

  (pass-if-exception "() -1" exception:out-of-range
    (split-at! '() -1))
  (pass-if (equal-values? '(() ())
			  (lambda () (split-at! '() 0))))
  (pass-if-exception "() 1" exception:wrong-type-arg
    (split-at! '() 1))

  (pass-if-exception "(1) -1" exception:out-of-range
    (split-at! (list 1) -1))
  (pass-if (equal-values? '(() (1)) (lambda () (split-at! (list 1) 0))))
  (pass-if (equal-values? '((1) ()) (lambda () (split-at! (list 1) 1))))
  (pass-if-exception "(1) 2" exception:wrong-type-arg
    (split-at! (list 1) 2))

  (pass-if-exception "(4 5) -1" exception:out-of-range
    (split-at! (list 4 5) -1))
  (pass-if (equal-values? '(() (4 5)) (lambda () (split-at! (list 4 5) 0))))
  (pass-if (equal-values? '((4) (5))  (lambda () (split-at! (list 4 5) 1))))
  (pass-if (equal-values? '((4 5) ()) (lambda () (split-at! (list 4 5) 2))))
  (pass-if-exception "(4 5) 3" exception:wrong-type-arg
    (split-at! (list 4 5) 3))

  (pass-if-exception "(4 5 6) -1" exception:out-of-range
    (split-at! (list 4 5 6) -1))
  (pass-if (equal-values? '(() (4 5 6)) (lambda () (split-at! (list 4 5 6) 0))))
  (pass-if (equal-values? '((4) (5 6))  (lambda () (split-at! (list 4 5 6) 1))))
  (pass-if (equal-values? '((4 5) (6))  (lambda () (split-at! (list 4 5 6) 2))))
  (pass-if (equal-values? '((4 5 6) ()) (lambda () (split-at! (list 4 5 6) 3))))
  (pass-if-exception "(4 5 6) 4" exception:wrong-type-arg
    (split-at! (list 4 5 6) 4)))

;;
;; span
;;

(with-test-prefix "span"

  (define (test-span lst want-v1 want-v2)
    (call-with-values
	(lambda ()
	  (span positive? lst))
      (lambda (got-v1 got-v2)
	(and (equal? got-v1 want-v1)
	     (equal? got-v2 want-v2)))))

  (pass-if "empty"
    (test-span '() '() '()))

  (pass-if "y"
    (test-span '(1) '(1) '()))

  (pass-if "n"
    (test-span '(-1) '() '(-1)))

  (pass-if "yy"
    (test-span '(1 2) '(1 2) '()))

  (pass-if "ny"
    (test-span '(-1 1) '() '(-1 1)))

  (pass-if "yn"
    (test-span '(1 -1) '(1) '(-1)))

  (pass-if "nn"
    (test-span '(-1 -2) '() '(-1 -2)))

  (pass-if "yyy"
    (test-span '(1 2 3) '(1 2 3) '()))

  (pass-if "nyy"
    (test-span '(-1 1 2) '() '(-1 1 2)))

  (pass-if "yny"
    (test-span '(1 -1 2) '(1) '(-1 2)))

  (pass-if "nny"
    (test-span '(-1 -2 1) '() '(-1 -2 1)))

  (pass-if "yyn"
    (test-span '(1 2 -1) '(1 2) '(-1)))

  (pass-if "nyn"
    (test-span '(-1 1 -2) '() '(-1 1 -2)))

  (pass-if "ynn"
    (test-span '(1 -1 -2) '(1) '(-1 -2)))

  (pass-if "nnn"
    (test-span '(-1 -2 -3) '() '(-1 -2 -3))))

;;
;; span!
;;

(with-test-prefix "span!"

  (define (test-span! lst want-v1 want-v2)
    (call-with-values
	(lambda ()
	  (span! positive? lst))
      (lambda (got-v1 got-v2)
	(and (equal? got-v1 want-v1)
	     (equal? got-v2 want-v2)))))

  (pass-if "empty"
    (test-span! '() '() '()))

  (pass-if "y"
    (test-span! (list 1) '(1) '()))

  (pass-if "n"
    (test-span! (list -1) '() '(-1)))

  (pass-if "yy"
    (test-span! (list 1 2) '(1 2) '()))

  (pass-if "ny"
    (test-span! (list -1 1) '() '(-1 1)))

  (pass-if "yn"
    (test-span! (list 1 -1) '(1) '(-1)))

  (pass-if "nn"
    (test-span! (list -1 -2) '() '(-1 -2)))

  (pass-if "yyy"
    (test-span! (list 1 2 3) '(1 2 3) '()))

  (pass-if "nyy"
    (test-span! (list -1 1 2) '() '(-1 1 2)))

  (pass-if "yny"
    (test-span! (list 1 -1 2) '(1) '(-1 2)))

  (pass-if "nny"
    (test-span! (list -1 -2 1) '() '(-1 -2 1)))

  (pass-if "yyn"
    (test-span! (list 1 2 -1) '(1 2) '(-1)))

  (pass-if "nyn"
    (test-span! (list -1 1 -2) '() '(-1 1 -2)))

  (pass-if "ynn"
    (test-span! (list 1 -1 -2) '(1) '(-1 -2)))

  (pass-if "nnn"
    (test-span! (list -1 -2 -3) '() '(-1 -2 -3))))

;;
;; take!
;;

(with-test-prefix "take!"

  (pass-if-exception "() -1" exception:out-of-range
    (take! '() -1))
  (pass-if (equal? '() (take! '() 0)))
  (pass-if-exception "() 1" exception:wrong-type-arg
    (take! '() 1))

  (pass-if-exception "(1) -1" exception:out-of-range
    (take! '(1) -1))
  (pass-if (equal? '() (take! '(1) 0)))
  (pass-if (equal? '(1) (take! '(1) 1)))
  (pass-if-exception "(1) 2" exception:wrong-type-arg
    (take! '(1) 2))

  (pass-if-exception "(4 5) -1" exception:out-of-range
    (take! '(4 5) -1))
  (pass-if (equal? '() (take! '(4 5) 0)))
  (pass-if (equal? '(4) (take! '(4 5) 1)))
  (pass-if (equal? '(4 5) (take! '(4 5) 2)))
  (pass-if-exception "(4 5) 3" exception:wrong-type-arg
    (take! '(4 5) 3))

  (pass-if-exception "(4 5 6) -1" exception:out-of-range
    (take! '(4 5 6) -1))
  (pass-if (equal? '() (take! '(4 5 6) 0)))
  (pass-if (equal? '(4) (take! '(4 5 6) 1)))
  (pass-if (equal? '(4 5) (take! '(4 5 6) 2)))
  (pass-if (equal? '(4 5 6) (take! '(4 5 6) 3)))
  (pass-if-exception "(4 5 6) 4" exception:wrong-type-arg
    (take! '(4 5 6) 4)))


;;
;; take-right
;;

(with-test-prefix "take-right"

  (pass-if-exception "() -1" exception:out-of-range
    (take-right '() -1))
  (pass-if (equal? '() (take-right '() 0)))
  (pass-if-exception "() 1" exception:wrong-type-arg
    (take-right '() 1))

  (pass-if-exception "(1) -1" exception:out-of-range
    (take-right '(1) -1))
  (pass-if (equal? '() (take-right '(1) 0)))
  (pass-if (equal? '(1) (take-right '(1) 1)))
  (pass-if-exception "(1) 2" exception:wrong-type-arg
    (take-right '(1) 2))

  (pass-if-exception "(4 5) -1" exception:out-of-range
    (take-right '(4 5) -1))
  (pass-if (equal? '() (take-right '(4 5) 0)))
  (pass-if (equal? '(5) (take-right '(4 5) 1)))
  (pass-if (equal? '(4 5) (take-right '(4 5) 2)))
  (pass-if-exception "(4 5) 3" exception:wrong-type-arg
    (take-right '(4 5) 3))

  (pass-if-exception "(4 5 6) -1" exception:out-of-range
    (take-right '(4 5 6) -1))
  (pass-if (equal? '() (take-right '(4 5 6) 0)))
  (pass-if (equal? '(6) (take-right '(4 5 6) 1)))
  (pass-if (equal? '(5 6) (take-right '(4 5 6) 2)))
  (pass-if (equal? '(4 5 6) (take-right '(4 5 6) 3)))
  (pass-if-exception "(4 5 6) 4" exception:wrong-type-arg
    (take-right '(4 5 6) 4))

  (pass-if "(a b . c) 0"
    (equal? (take-right '(a b . c) 0) 'c))
  (pass-if "(a b . c) 1"
    (equal? (take-right '(a b . c) 1) '(b . c))))

;;
;; tenth
;;

(with-test-prefix "tenth"
  (pass-if-exception "() -1" exception:wrong-type-arg
    (tenth '(a b c d e f g h i)))
  (pass-if (eq? 'j (tenth '(a b c d e f g h i j))))
  (pass-if (eq? 'j (tenth '(a b c d e f g h i j k)))))

;;
;; xcons
;;

(with-test-prefix "xcons"
  (pass-if (equal? '(y . x) (xcons 'x 'y))))