guile/test-suite/tests/syntax.test

;;;; syntax.test --- test suite for Guile's syntactic forms    -*- scheme -*-
;;;;
;;;; Copyright (C) 2001, 2003 Free Software Foundation, Inc.
;;;; 
;;;; This program is free software; you can redistribute it and/or modify
;;;; it under the terms of the GNU General Public License as published by
;;;; the Free Software Foundation; either version 2, or (at your option)
;;;; any later version.
;;;; 
;;;; This program 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 General Public License for more details.
;;;; 
;;;; You should have received a copy of the GNU General Public License
;;;; along with this software; see the file COPYING.  If not, write to
;;;; the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
;;;; Boston, MA 02111-1307 USA

(define-module (test-suite test-syntax)
  :use-module (test-suite lib))


(define exception:bad-expression
  (cons 'syntax-error "Bad expression"))

(define exception:missing/extra-expr
  (cons 'syntax-error "Missing or extra expression"))
(define exception:missing-expr
  (cons 'syntax-error "Missing expression"))
(define exception:missing-body-expr
  (cons 'syntax-error "Missing body expression"))
(define exception:extra-expr
  (cons 'syntax-error "Extra expression"))
(define exception:illegal-empty-combination
  (cons 'syntax-error "Illegal empty combination"))

(define exception:bad-bindings
  (cons 'syntax-error "Bad bindings"))
(define exception:bad-binding
  (cons 'syntax-error "Bad binding"))
(define exception:duplicate-binding
  (cons 'syntax-error "Duplicate binding"))
(define exception:bad-body
  (cons 'misc-error "^bad body"))
(define exception:bad-formals
  (cons 'syntax-error "Bad formals"))
(define exception:bad-formal
  (cons 'syntax-error "Bad formal"))
(define exception:duplicate-formal
  (cons 'syntax-error "Duplicate formal"))

(define exception:missing-clauses
  (cons 'syntax-error "Missing clauses"))
(define exception:misplaced-else-clause
  (cons 'syntax-error "Misplaced else clause"))
(define exception:bad-case-clause
  (cons 'syntax-error "Bad case clause"))
(define exception:bad-case-labels
  (cons 'syntax-error "Bad case labels"))
(define exception:bad-cond-clause
  (cons 'syntax-error "Bad cond clause"))


(with-test-prefix "expressions"

  (with-test-prefix "Bad argument list"

    (pass-if-exception "improper argument list of length 1"
      exception:wrong-num-args
      (eval '(let ((foo (lambda (x y) #t)))
	       (foo . 1))
	    (interaction-environment)))

    (pass-if-exception "improper argument list of length 2"
      exception:wrong-num-args
      (eval '(let ((foo (lambda (x y) #t)))
	       (foo 1 . 2))
	    (interaction-environment))))

  (with-test-prefix "missing or extra expression"

    ;; R5RS says:
    ;; *Note:* In many dialects of Lisp, the empty combination, (),
    ;; is a legitimate expression.  In Scheme, combinations must
    ;; have at least one subexpression, so () is not a syntactically
    ;; valid expression.

    ;; Fixed on 2001-3-3
    (pass-if-exception "empty parentheses \"()\""
      exception:illegal-empty-combination
      (eval '()
	    (interaction-environment)))))

(with-test-prefix "quote"
  #t)

(with-test-prefix "quasiquote"

  (with-test-prefix "unquote"

    (pass-if "repeated execution"
      (let ((foo (let ((i 0)) (lambda () (set! i (+ i 1)) `(,i)))))
	(and (equal? (foo) '(1)) (equal? (foo) '(2))))))

  (with-test-prefix "unquote-splicing"

    (pass-if-exception "extra arguments"
      exception:missing/extra-expr
      (quasiquote ((unquote-splicing (list 1 2) (list 3 4)))))))

(with-test-prefix "begin"

  (pass-if "legal (begin)"
    (begin)
    #t)

  (expect-fail-exception "illegal (begin)"
    exception:bad-body
    (if #t (begin))
    #t))

(with-test-prefix "lambda"

  (with-test-prefix "bad formals"

    (pass-if-exception "(lambda)"
      exception:missing-expr
      (eval '(lambda)
	    (interaction-environment)))

    (pass-if-exception "(lambda . \"foo\")"
      exception:bad-expression
      (eval '(lambda . "foo")
	    (interaction-environment)))

    (pass-if-exception "(lambda \"foo\")"
      exception:missing-expr
      (eval '(lambda "foo")
	    (interaction-environment)))

    (pass-if-exception "(lambda \"foo\" #f)"
      exception:bad-formals
      (eval '(lambda "foo" #f)
	    (interaction-environment)))

    (pass-if-exception "(lambda (x 1) 2)"
      exception:bad-formal
      (eval '(lambda (x 1) 2)
	    (interaction-environment)))

    (pass-if-exception "(lambda (1 x) 2)"
      exception:bad-formal
      (eval '(lambda (1 x) 2)
	    (interaction-environment)))

    (pass-if-exception "(lambda (x \"a\") 2)"
      exception:bad-formal
      (eval '(lambda (x "a") 2)
	    (interaction-environment)))

    (pass-if-exception "(lambda (\"a\" x) 2)"
      exception:bad-formal
      (eval '(lambda ("a" x) 2)
	    (interaction-environment))))

  (with-test-prefix "duplicate formals"

    ;; Fixed on 2001-3-3
    (pass-if-exception "(lambda (x x) 1)"
      exception:duplicate-formal
      (eval '(lambda (x x) 1)
	    (interaction-environment)))

    ;; Fixed on 2001-3-3
    (pass-if-exception "(lambda (x x x) 1)"
      exception:duplicate-formal
      (eval '(lambda (x x x) 1)
	    (interaction-environment))))

  (with-test-prefix "bad body"

    (pass-if-exception "(lambda ())"
      exception:missing-expr
      (eval '(lambda ())
	    (interaction-environment)))))

(with-test-prefix "let"

  (with-test-prefix "bindings"

    (pass-if-exception "late binding"
      exception:unbound-var
      (let ((x 1) (y x)) y)))

  (with-test-prefix "bad bindings"

    (pass-if-exception "(let)"
      exception:missing-expr
      (eval '(let)
	    (interaction-environment)))

    (pass-if-exception "(let 1)"
      exception:missing-expr
      (eval '(let 1)
	    (interaction-environment)))

    (pass-if-exception "(let (x))"
      exception:missing-expr
      (eval '(let (x))
	    (interaction-environment)))

    (pass-if-exception "(let ((x)))"
      exception:missing-expr
      (eval '(let ((x)))
	    (interaction-environment)))

    (pass-if-exception "(let (x) 1)"
      exception:bad-binding
      (eval '(let (x) 1)
	    (interaction-environment)))

    (pass-if-exception "(let ((x)) 3)"
      exception:bad-binding
      (eval '(let ((x)) 3)
	    (interaction-environment)))

    (pass-if-exception "(let ((x 1) y) x)"
      exception:bad-binding
      (eval '(let ((x 1) y) x)
	    (interaction-environment)))

    (pass-if-exception "(let ((1 2)) 3)"
      exception:bad-variable
      (eval '(let ((1 2)) 3)
	    (interaction-environment))))

  (with-test-prefix "duplicate bindings"

    (pass-if-exception "(let ((x 1) (x 2)) x)"
      exception:duplicate-binding
      (eval '(let ((x 1) (x 2)) x)
	    (interaction-environment))))

  (with-test-prefix "bad body"

    (pass-if-exception "(let ())"
      exception:missing-expr
      (eval '(let ())
	    (interaction-environment)))

    (pass-if-exception "(let ((x 1)))"
      exception:missing-expr
      (eval '(let ((x 1)))
	    (interaction-environment)))))

(with-test-prefix "named let"

  (with-test-prefix "initializers"

    (pass-if "evaluated in outer environment"
      (let ((f -))
	(eqv? (let f ((n (f 1))) n) -1))))

  (with-test-prefix "bad bindings"

    (pass-if-exception "(let x (y))"
      exception:missing-expr
      (eval '(let x (y))
	    (interaction-environment))))

  (with-test-prefix "bad body"

    (pass-if-exception "(let x ())"
      exception:missing-expr
      (eval '(let x ())
	    (interaction-environment)))

    (pass-if-exception "(let x ((y 1)))"
      exception:missing-expr
      (eval '(let x ((y 1)))
	    (interaction-environment)))))

(with-test-prefix "let*"

  (with-test-prefix "bindings"

    (pass-if "(let* ((x 1) (x 2)) ...)"
      (let* ((x 1) (x 2))
	(= x 2)))

    (pass-if "(let* ((x 1) (x x)) ...)"
      (let* ((x 1) (x x))
	(= x 1))))

  (with-test-prefix "bad bindings"

    (pass-if-exception "(let*)"
      exception:missing-expr
      (eval '(let*)
	    (interaction-environment)))

    (pass-if-exception "(let* 1)"
      exception:missing-expr
      (eval '(let* 1)
	    (interaction-environment)))

    (pass-if-exception "(let* (x))"
      exception:missing-expr
      (eval '(let* (x))
	    (interaction-environment)))

    (pass-if-exception "(let* (x) 1)"
      exception:bad-binding
      (eval '(let* (x) 1)
	    (interaction-environment)))

    (pass-if-exception "(let* ((x)) 3)"
      exception:bad-binding
      (eval '(let* ((x)) 3)
	    (interaction-environment)))

    (pass-if-exception "(let* ((x 1) y) x)"
      exception:bad-binding
      (eval '(let* ((x 1) y) x)
	    (interaction-environment)))

    (pass-if-exception "(let* x ())"
      exception:bad-bindings
      (eval '(let* x ())
	    (interaction-environment)))

    (pass-if-exception "(let* x (y))"
      exception:bad-bindings
      (eval '(let* x (y))
	    (interaction-environment)))

    (pass-if-exception "(let* ((1 2)) 3)"
      exception:bad-variable
      (eval '(let* ((1 2)) 3)
	    (interaction-environment))))

  (with-test-prefix "bad body"

    (pass-if-exception "(let* ())"
      exception:missing-expr
      (eval '(let* ())
	    (interaction-environment)))

    (pass-if-exception "(let* ((x 1)))"
      exception:missing-expr
      (eval '(let* ((x 1)))
	    (interaction-environment)))))

(with-test-prefix "letrec"

  (with-test-prefix "bindings"

    (pass-if-exception "initial bindings are undefined"
      exception:unbound-var
      (let ((x 1))
	(letrec ((x 1) (y x)) y))))

  (with-test-prefix "bad bindings"

    (pass-if-exception "(letrec)"
      exception:missing-expr
      (eval '(letrec)
	    (interaction-environment)))

    (pass-if-exception "(letrec 1)"
      exception:missing-expr
      (eval '(letrec 1)
	    (interaction-environment)))

    (pass-if-exception "(letrec (x))"
      exception:missing-expr
      (eval '(letrec (x))
	    (interaction-environment)))

    (pass-if-exception "(letrec (x) 1)"
      exception:bad-binding
      (eval '(letrec (x) 1)
	    (interaction-environment)))

    (pass-if-exception "(letrec ((x)) 3)"
      exception:bad-binding
      (eval '(letrec ((x)) 3)
	    (interaction-environment)))

    (pass-if-exception "(letrec ((x 1) y) x)"
      exception:bad-binding
      (eval '(letrec ((x 1) y) x)
	    (interaction-environment)))

    (pass-if-exception "(letrec x ())"
      exception:bad-bindings
      (eval '(letrec x ())
	    (interaction-environment)))

    (pass-if-exception "(letrec x (y))"
      exception:bad-bindings
      (eval '(letrec x (y))
	    (interaction-environment)))

    (pass-if-exception "(letrec ((1 2)) 3)"
      exception:bad-variable
      (eval '(letrec ((1 2)) 3)
	    (interaction-environment))))

  (with-test-prefix "duplicate bindings"

    (pass-if-exception "(letrec ((x 1) (x 2)) x)"
      exception:duplicate-binding
      (eval '(letrec ((x 1) (x 2)) x)
	    (interaction-environment))))

  (with-test-prefix "bad body"

    (pass-if-exception "(letrec ())"
      exception:missing-expr
      (eval '(letrec ())
	    (interaction-environment)))

    (pass-if-exception "(letrec ((x 1)))"
      exception:missing-expr
      (eval '(letrec ((x 1)))
	    (interaction-environment)))))

(with-test-prefix "if"

  (with-test-prefix "missing or extra expressions"

    (pass-if-exception "(if)"
      exception:missing/extra-expr
      (eval '(if)
	    (interaction-environment)))

    (pass-if-exception "(if 1 2 3 4)"
      exception:missing/extra-expr
      (eval '(if 1 2 3 4)
	    (interaction-environment)))))

(with-test-prefix "cond"

  (with-test-prefix "bad or missing clauses"

    (pass-if-exception "(cond)"
      exception:missing-clauses
      (eval '(cond)
	    (interaction-environment)))

    (pass-if-exception "(cond #t)"
      exception:bad-cond-clause
      (eval '(cond #t)
	    (interaction-environment)))

    (pass-if-exception "(cond 1)"
      exception:bad-cond-clause
      (eval '(cond 1)
	    (interaction-environment)))

    (pass-if-exception "(cond 1 2)"
      exception:bad-cond-clause
      (eval '(cond 1 2)
	    (interaction-environment)))

    (pass-if-exception "(cond 1 2 3)"
      exception:bad-cond-clause
      (eval '(cond 1 2 3)
	    (interaction-environment)))

    (pass-if-exception "(cond 1 2 3 4)"
      exception:bad-cond-clause
      (eval '(cond 1 2 3 4)
	    (interaction-environment)))

    (pass-if-exception "(cond ())"
      exception:bad-cond-clause
      (eval '(cond ())
	    (interaction-environment)))

    (pass-if-exception "(cond () 1)"
      exception:bad-cond-clause
      (eval '(cond () 1)
	    (interaction-environment)))

    (pass-if-exception "(cond (1) 1)"
      exception:bad-cond-clause
      (eval '(cond (1) 1)
	    (interaction-environment)))))

(with-test-prefix "cond =>"

  (with-test-prefix "cond is hygienic"

    (pass-if "bound 'else is handled correctly"
      (eq? (let ((else 'ok)) (cond (else))) 'ok))

    (pass-if "bound '=> is handled correctly"
      (eq? (let ((=> #f)) (cond (#t => 'ok))) 'ok)))

  (with-test-prefix "else is handled correctly"

    (pass-if "else =>"
      (let ((=> 'foo))
	(eq? (cond (else =>)) 'foo)))

    (pass-if "else => identity"
      (let* ((=> 'foo))
	(eq? (cond (else => identity)) identity))))

  (with-test-prefix "wrong number of arguments"

    (pass-if-exception "=> (lambda (x y) #t)"
      exception:wrong-num-args
      (cond (1 => (lambda (x y) #t))))))

(with-test-prefix "case"

  (pass-if "clause with empty labels list"
    (case 1 (() #f) (else #t)))

  (with-test-prefix "case is hygienic"

    (pass-if-exception "bound 'else is handled correctly"
      exception:bad-case-labels
      (eval '(let ((else #f)) (case 1 (else #f)))
            (interaction-environment))))

  (with-test-prefix "bad or missing clauses"

    (pass-if-exception "(case)"
      exception:missing-clauses
      (eval '(case)
	    (interaction-environment)))

    (pass-if-exception "(case . \"foo\")"
      exception:bad-expression
      (eval '(case . "foo")
	    (interaction-environment)))

    (pass-if-exception "(case 1)"
      exception:missing-clauses
      (eval '(case 1)
	    (interaction-environment)))

    (pass-if-exception "(case 1 . \"foo\")"
      exception:bad-expression
      (eval '(case 1 . "foo")
	    (interaction-environment)))

    (pass-if-exception "(case 1 \"foo\")"
      exception:bad-case-clause
      (eval '(case 1 "foo")
	    (interaction-environment)))

    (pass-if-exception "(case 1 ())"
      exception:bad-case-clause
      (eval '(case 1 ())
	    (interaction-environment)))

    (pass-if-exception "(case 1 (\"foo\"))"
      exception:bad-case-clause
      (eval '(case 1 ("foo"))
	    (interaction-environment)))

    (pass-if-exception "(case 1 (\"foo\" \"bar\"))"
      exception:bad-case-labels
      (eval '(case 1 ("foo" "bar"))
	    (interaction-environment)))

    (pass-if-exception "(case 1 ((2) \"bar\") . \"foo\")"
      exception:bad-expression
      (eval '(case 1 ((2) "bar") . "foo")
	    (interaction-environment)))

    (pass-if-exception "(case 1 ((2) \"bar\") (else))"
      exception:bad-case-clause
      (eval '(case 1 ((2) "bar") (else))
	    (interaction-environment)))

    (pass-if-exception "(case 1 (else #f) . \"foo\")"
      exception:bad-expression
      (eval '(case 1 (else #f) . "foo")
	    (interaction-environment)))

    (pass-if-exception "(case 1 (else #f) ((1) #t))"
      exception:misplaced-else-clause
      (eval '(case 1 (else #f) ((1) #t))
	    (interaction-environment)))))

(with-test-prefix "top-level define"

  (with-test-prefix "currying"

    (pass-if "(define ((foo)) #f)"
      (eval '(begin
               (define ((foo)) #t)
               ((foo)))
            (interaction-environment))))

  (with-test-prefix "missing or extra expressions"

    (pass-if-exception "(define)"
      exception:missing-expr
      (eval '(define)
	    (interaction-environment)))))

(with-test-prefix "internal define"

  (pass-if "internal defines become letrec"
    (eval '(let ((a identity) (b identity) (c identity))
             (define (a x) (if (= x 0) 'a (b (- x 1))))
             (define (b x) (if (= x 0) 'b (c (- x 1))))
             (define (c x) (if (= x 0) 'c (a (- x 1))))
             (and (eq? 'a (a 0) (a 3))
                  (eq? 'b (a 1) (a 4))
                  (eq? 'c (a 2) (a 5))))
          (interaction-environment)))

  (expect-fail "internal defines with begin"
    (false-if-exception
     (eval '(let ((a identity) (b identity) (c identity))
              (define (a x) (if (= x 0) 'a (b (- x 1))))
              (begin
                (define (b x) (if (= x 0) 'b (c (- x 1)))))
              (define (c x) (if (= x 0) 'c (a (- x 1))))
              (and (eq? 'a (a 0) (a 3))
                   (eq? 'b (a 1) (a 4))
                   (eq? 'c (a 2) (a 5))))
           (interaction-environment))))

  (expect-fail "internal defines with empty begin"
    (false-if-exception
     (eval '(let ((a identity) (b identity) (c identity))
              (define (a x) (if (= x 0) 'a (b (- x 1))))
              (begin)
              (define (b x) (if (= x 0) 'b (c (- x 1))))
              (define (c x) (if (= x 0) 'c (a (- x 1))))
              (and (eq? 'a (a 0) (a 3))
                   (eq? 'b (a 1) (a 4))
                   (eq? 'c (a 2) (a 5))))
           (interaction-environment))))

  (pass-if "internal defines with macro application"
    (false-if-exception
     (eval '(begin
              (defmacro my-define forms
                (cons 'define forms))
              (let ((a identity) (b identity) (c identity))
                (define (a x) (if (= x 0) 'a (b (- x 1))))
                (my-define (b x) (if (= x 0) 'b (c (- x 1))))
                (define (c x) (if (= x 0) 'c (a (- x 1))))
                (and (eq? 'a (a 0) (a 3))
                     (eq? 'b (a 1) (a 4))
                     (eq? 'c (a 2) (a 5)))))
           (interaction-environment))))

  (pass-if-exception "missing body expression"
    exception:missing-body-expr
    (eval '(let () (define x #t))
          (interaction-environment))))

(with-test-prefix "set!"

  (with-test-prefix "missing or extra expressions"

    (pass-if-exception "(set!)"
      exception:missing/extra-expr
      (eval '(set!)
	    (interaction-environment)))

    (pass-if-exception "(set! 1)"
      exception:missing/extra-expr
      (eval '(set! 1)
	    (interaction-environment)))

    (pass-if-exception "(set! 1 2 3)"
      exception:missing/extra-expr
      (eval '(set! 1 2 3)
	    (interaction-environment))))

  (with-test-prefix "bad variable"

    (pass-if-exception "(set! \"\" #t)"
      exception:bad-variable
      (eval '(set! "" #t)
	    (interaction-environment)))

    (pass-if-exception "(set! 1 #t)"
      exception:bad-variable
      (eval '(set! 1 #t)
	    (interaction-environment)))

    (pass-if-exception "(set! #t #f)"
      exception:bad-variable
      (eval '(set! #t #f)
	    (interaction-environment)))

    (pass-if-exception "(set! #f #t)"
      exception:bad-variable
      (eval '(set! #f #t)
	    (interaction-environment)))

    (pass-if-exception "(set! #\space #f)"
      exception:bad-variable
      (eval '(set! #\space #f)
	    (interaction-environment)))))

(with-test-prefix "quote"

  (with-test-prefix "missing or extra expression"

    (pass-if-exception "(quote)"
      exception:missing/extra-expr
      (eval '(quote)
	    (interaction-environment)))

    (pass-if-exception "(quote a b)"
      exception:missing/extra-expr
      (eval '(quote a b)
	    (interaction-environment)))))

(with-test-prefix "while"
  
  (define (unreachable)
    (error "unreachable code has been reached!"))
  
  ;; Return a new procedure COND which when called (COND) will return #t the
  ;; first N times, then #f, then any further call is an error.  N=0 is
  ;; allowed, in which case #f is returned by the first call.
  (define (make-iterations-cond n)
    (lambda ()
      (cond ((not n)
	     (error "oops, condition re-tested after giving false"))
	    ((= 0 n)
	     (set! n #f)
	     #f)
	    (else
	     (set! n (1- n))
	     #t))))
  

  (pass-if-exception "too few args" exception:wrong-num-args
    (eval '(while) (interaction-environment)))
  
  (with-test-prefix "empty body"
    (do ((n 0 (1+ n)))
	((> n 5))
      (pass-if n
	(let ((cond (make-iterations-cond n)))
	  (while (cond)))
	#t)))
  
  (pass-if "initially false"
    (while #f
      (unreachable))
    #t)
  
  (with-test-prefix "in empty environment"

    ;; an environment with no bindings at all
    (define empty-environment
      (make-module 1))
      
    (pass-if "empty body"
      (eval `(,while #f)
	    empty-environment)
      #t)
    
    (pass-if "initially false"
      (eval `(,while #f
	       #f)
	    empty-environment)
      #t)
    
    (pass-if "iterating"
      (let ((cond (make-iterations-cond 3)))
	(eval `(,while (,cond)
		 123 456)
	      empty-environment))
      #t))
  
  (with-test-prefix "iterations"
    (do ((n 0 (1+ n)))
	((> n 5))
      (pass-if n
	(let ((cond (make-iterations-cond n))
	      (i    0))
	  (while (cond)
	    (set! i (1+ i)))
	  (= i n)))))
  
  (with-test-prefix "break"
    
    (pass-if-exception "too many args" exception:wrong-num-args
      (while #t
	(break 1)))
    
    (with-test-prefix "from cond"
      (pass-if "first"
	(while (begin
		 (break)
		 (unreachable))
	  (unreachable))
	#t)
      
      (do ((n 0 (1+ n)))
	  ((> n 5))
	(pass-if n
	  (let ((cond (make-iterations-cond n))
		(i    0))
	    (while (if (cond)
		       #t
		       (begin
			 (break)
			 (unreachable)))
	      (set! i (1+ i)))
	    (= i n)))))
    
    (with-test-prefix "from body"
      (pass-if "first"
	(while #t
	  (break)
	  (unreachable))
	#t)
      
      (do ((n 0 (1+ n)))
	  ((> n 5))
	(pass-if n
	  (let ((cond (make-iterations-cond n))
		(i    0))
	    (while #t
	      (if (not (cond))
		  (begin
		    (break)
		    (unreachable)))
	      (set! i (1+ i)))
	    (= i n)))))
    
    (pass-if "from nested"
      (while #t
	(let ((outer-break break))
	  (while #t
	    (outer-break)
	    (unreachable)))
	(unreachable))
      #t)
    
    (pass-if "from recursive"
      (let ((outer-break #f))
	(define (r n)
	  (while #t
	    (if (eq? n 'outer)
		(begin
		  (set! outer-break break)
		  (r 'inner))
		(begin
		  (outer-break)
		  (unreachable))))
	  (if (eq? n 'inner)
	      (error "broke only from inner loop")))
	(r 'outer))
      #t))
  
  (with-test-prefix "continue"
    
    (pass-if-exception "too many args" exception:wrong-num-args
      (while #t
	(continue 1)))
    
    (with-test-prefix "from cond"
      (do ((n 0 (1+ n)))
	  ((> n 5))
	(pass-if n
	  (let ((cond (make-iterations-cond n))
		(i    0))
	    (while (if (cond)
		       (begin
			 (set! i (1+ i))
			 (continue)
			 (unreachable))
		       #f)
	      (unreachable))
	    (= i n)))))
    
    (with-test-prefix "from body"
      (do ((n 0 (1+ n)))
	  ((> n 5))
	(pass-if n
	  (let ((cond (make-iterations-cond n))
		(i    0))
	    (while (cond)
	      (set! i (1+ i))
	      (continue)
	      (unreachable))
	    (= i n)))))
    
    (pass-if "from nested"
      (let ((cond (make-iterations-cond 3)))
	(while (cond)
	  (let ((outer-continue continue))
	    (while #t
	      (outer-continue)
	      (unreachable)))))
      #t)
    
    (pass-if "from recursive"
      (let ((outer-continue #f))
	(define (r n)
	  (let ((cond  (make-iterations-cond 3))
		(first #t))
	    (while (begin
		     (if (and (not first)
			      (eq? n 'inner))
			 (error "continued only to inner loop"))
		     (cond))
	      (set! first #f)
	      (if (eq? n 'outer)
		  (begin
		    (set! outer-continue continue)
		    (r 'inner))
		  (begin
		    (outer-continue)
		    (unreachable))))))
	(r 'outer))
      #t)))