ikarus/scheme/ikarus.lists.ss

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;;; Ikarus Scheme -- A compiler for R6RS Scheme.
;;; Copyright (C) 2006,2007 Abdulaziz Ghuloum
;;;
;;; This program is free software: you can redistribute it and/or modify
;;; it under the terms of the GNU General Public License version 3 as
;;; published by the Free Software Foundation.
;;;
;;; 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 program. If not, see <http://www.gnu.org/licenses/>.
(library (ikarus lists)
(export $memq list? list cons* make-list append length list-ref reverse
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last-pair memq memp memv member find assq assp assv assoc
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remq remv remove remp filter map for-each andmap ormap list-tail
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partition for-all exists fold-left fold-right)
(import
(ikarus system $fx)
(ikarus system $pairs)
(except (ikarus) list? list cons* make-list append reverse
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last-pair length list-ref memq memp memv member find
assq assp assv assoc remq remv remove remp filter
map for-each andmap ormap list-tail partition
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for-all exists fold-left fold-right))
(define $memq
(lambda (x ls)
(let f ([x x] [ls ls])
(and (pair? ls)
(if (eq? x (car ls))
ls
(f x (cdr ls)))))))
(define list (lambda x x))
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(define cons*
(lambda (fst . rest)
(let f ([fst fst] [rest rest])
(cond
[(null? rest) fst]
[else
(cons fst (f ($car rest) ($cdr rest)))]))))
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(define list?
(letrec ([race
(lambda (h t)
(if (pair? h)
(let ([h ($cdr h)])
(if (pair? h)
(and (not (eq? h t))
(race ($cdr h) ($cdr t)))
(null? h)))
(null? h)))])
(lambda (x) (race x x))))
(module (make-list)
(define f
(lambda (n fill ls)
(cond
[($fxzero? n) ls]
[else
(f ($fxsub1 n) fill (cons fill ls))])))
(define make-list
(case-lambda
[(n)
(if (and (fixnum? n) ($fx>= n 0))
(f n (void) '())
(error 'make-list "not a valid length" n))]
[(n fill)
(if (and (fixnum? n) ($fx>= n 0))
(f n fill '())
(error 'make-list "not a valid length" n))])))
(define length
(letrec ([race
(lambda (h t ls n)
(if (pair? h)
(let ([h ($cdr h)])
(if (pair? h)
(if (not (eq? h t))
(race ($cdr h) ($cdr t) ls ($fx+ n 2))
(error 'length "circular list" ls))
(if (null? h)
($fx+ n 1)
(error 'length "not a proper list" ls))))
(if (null? h)
n
(error 'length "not a proper list" ls))))])
(lambda (ls)
(race ls ls ls 0))))
(define list-ref
(lambda (list index)
(define f
(lambda (ls i)
(cond
[($fxzero? i)
(if (pair? ls)
($car ls)
(error 'list-ref "index is out of range" index list))]
[(pair? ls)
(f ($cdr ls) ($fxsub1 i))]
[(null? ls)
(error 'list-rec "index is out of range" index list)]
[else (error 'list-ref "not a list" list)])))
(unless (and (fixnum? index) ($fx>= index 0))
(error 'list-ref "not a valid index" index))
(f list index)))
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(define list-tail
(lambda (list index)
(define f
(lambda (ls i)
(cond
[($fxzero? i) ls]
[(pair? ls)
(f ($cdr ls) ($fxsub1 i))]
[(null? ls)
(error 'list-tail "index is out of range" index list)]
[else (error 'list-tail "not a list" list)])))
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(unless (and (fixnum? index) ($fx>= index 0))
(error 'list-tail "not a valid index" index))
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(f list index)))
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(module (append)
(define reverse
(lambda (h t ls ac)
(if (pair? h)
(let ([h ($cdr h)] [a1 ($car h)])
(if (pair? h)
(if (not (eq? h t))
(let ([a2 ($car h)])
(reverse ($cdr h) ($cdr t) ls (cons a2 (cons a1 ac))))
(error 'append "circular list" ls))
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(if (null? h)
(cons a1 ac)
(error 'append "not a proper list" ls))))
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(if (null? h)
ac
(error 'append "not a proper list" ls)))))
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(define revcons
(lambda (ls ac)
(cond
[(null? ls) ac]
[else
(revcons ($cdr ls) (cons ($car ls) ac))])))
(define append1
(lambda (ls ls*)
(cond
[(null? ls*) ls]
[else
(revcons (reverse ls ls ls '())
(append1 ($car ls*) ($cdr ls*)))])))
(define append
(case-lambda
[() '()]
[(ls) ls]
[(ls . ls*)
(append1 ls ls*)])))
(define reverse
(letrec ([race
(lambda (h t ls ac)
(if (pair? h)
(let ([h ($cdr h)] [ac (cons ($car h) ac)])
(if (pair? h)
(if (not (eq? h t))
(race ($cdr h) ($cdr t) ls (cons ($car h) ac))
(error 'reverse "circular list" ls))
(if (null? h)
ac
(error 'reverse "not a proper list" ls))))
(if (null? h)
ac
(error 'reverse "not a proper list" ls))))])
(lambda (x)
(race x x x '()))))
(define last-pair
(letrec ([race
(lambda (h t ls last)
(if (pair? h)
(let ([h ($cdr h)] [last h])
(if (pair? h)
(if (not (eq? h t))
(race ($cdr h) ($cdr t) ls h)
(error 'last-pair "circular list" ls))
last))
last))])
(lambda (x)
(if (pair? x)
(let ([d (cdr x)])
(race d d x x))
(error 'last-pair "not a pair" x)))))
(define memq
(letrec ([race
(lambda (h t ls x)
(if (pair? h)
(if (eq? ($car h) x)
h
(let ([h ($cdr h)])
(if (pair? h)
(if (eq? ($car h) x)
h
(if (not (eq? h t))
(race ($cdr h) ($cdr t) ls x)
(error 'memq "circular list" ls)))
(if (null? h)
'#f
(error 'memq "not a proper list" ls)))))
(if (null? h)
'#f
(error 'memq "not a proper list" ls))))])
(lambda (x ls)
(race ls ls ls x))))
(define memv
(letrec ([race
(lambda (h t ls x)
(if (pair? h)
(if (eqv? ($car h) x)
h
(let ([h ($cdr h)])
(if (pair? h)
(if (eqv? ($car h) x)
h
(if (not (eq? h t))
(race ($cdr h) ($cdr t) ls x)
(error 'memv "circular list" ls)))
(if (null? h)
'#f
(error 'memv "not a proper list" ls)))))
(if (null? h)
'#f
(error 'memv "not a proper list" ls))))])
(lambda (x ls)
(race ls ls ls x))))
(define member
(letrec ([race
(lambda (h t ls x)
(if (pair? h)
(if (equal? ($car h) x)
h
(let ([h ($cdr h)])
(if (pair? h)
(if (equal? ($car h) x)
h
(if (not (eq? h t))
(race ($cdr h) ($cdr t) ls x)
(error 'member "circular list" ls)))
(if (null? h)
'#f
(error 'member "not a proper list" ls)))))
(if (null? h)
'#f
(error 'member "not a proper list" ls))))])
(lambda (x ls)
(race ls ls ls x))))
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(define memp
(letrec ([race
(lambda (h t ls p)
(if (pair? h)
(if (p ($car h))
h
(let ([h ($cdr h)])
(if (pair? h)
(if (p ($car h))
h
(if (not (eq? h t))
(race ($cdr h) ($cdr t) ls p)
(error 'memp "circular list" ls)))
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(if (null? h)
'#f
(error 'memp "not a proper list" ls)))))
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(if (null? h)
'#f
(error 'memp "not a proper list" ls))))])
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(lambda (p ls)
(unless (procedure? p)
(error 'memp "not a procedure" p))
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(race ls ls ls p))))
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(define find
(letrec ([race
(lambda (h t ls p)
(if (pair? h)
(let ([a ($car h)])
(if (p a)
a
(let ([h ($cdr h)])
(if (pair? h)
(let ([a ($car h)])
(if (p a)
a
(if (not (eq? h t))
(race ($cdr h) ($cdr t) ls p)
(error 'find "circular list" ls))))
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(if (null? h)
'#f
(error 'find "not a proper list" ls))))))
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(if (null? h)
'#f
(error 'find "not a proper list" ls))))])
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(lambda (p ls)
(unless (procedure? p)
(error 'find "not a procedure" p))
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(race ls ls ls p))))
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(define assq
(letrec ([race
(lambda (x h t ls)
(if (pair? h)
(let ([a ($car h)] [h ($cdr h)])
(if (pair? a)
(if (eq? ($car a) x)
a
(if (pair? h)
(if (not (eq? h t))
(let ([a ($car h)])
(if (pair? a)
(if (eq? ($car a) x)
a
(race x ($cdr h) ($cdr t) ls))
(error 'assq "malformed alist"
ls)))
(error 'assq "circular list" ls))
(if (null? h)
#f
(error 'assq "not a proper list" ls))))
(error 'assq "malformed alist" ls)))
(if (null? h)
#f
(error 'assq "not a proper list" ls))))])
(lambda (x ls)
(race x ls ls ls))))
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(define assp
(letrec ([race
(lambda (p h t ls)
(if (pair? h)
(let ([a ($car h)] [h ($cdr h)])
(if (pair? a)
(if (p ($car a))
a
(if (pair? h)
(if (not (eq? h t))
(let ([a ($car h)])
(if (pair? a)
(if (p ($car a))
a
(race p ($cdr h) ($cdr t) ls))
(error 'assp "malformed alist"
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ls)))
(error 'assp "circular list" ls))
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(if (null? h)
#f
(error 'assp "not a proper list" ls))))
(error 'assp "malformed alist" ls)))
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(if (null? h)
#f
(error 'assp "not a proper list" ls))))])
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(lambda (p ls)
(unless (procedure? p)
(error 'assp "not a procedure" p))
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(race p ls ls ls))))
(define assv
(letrec ([race
(lambda (x h t ls)
(if (pair? h)
(let ([a ($car h)] [h ($cdr h)])
(if (pair? a)
(if (eqv? ($car a) x)
a
(if (pair? h)
(if (not (eq? h t))
(let ([a ($car h)])
(if (pair? a)
(if (eqv? ($car a) x)
a
(race x ($cdr h) ($cdr t) ls))
(error 'assv "malformed alist"
ls)))
(error 'assv "circular list" ls))
(if (null? h)
#f
(error 'assv "not a proper list" ls))))
(error 'assv "malformed alist" ls)))
(if (null? h)
#f
(error 'assv "not a proper list" ls))))])
(lambda (x ls)
(race x ls ls ls))))
(define assoc
(letrec ([race
(lambda (x h t ls)
(if (pair? h)
(let ([a ($car h)] [h ($cdr h)])
(if (pair? a)
(if (equal? ($car a) x)
a
(if (pair? h)
(if (not (eq? h t))
(let ([a ($car h)])
(if (pair? a)
(if (equal? ($car a) x)
a
(race x ($cdr h) ($cdr t) ls))
(error 'assoc "malformed alist"
ls)))
(error 'assoc "circular list" ls))
(if (null? h)
#f
(error 'assoc "not a proper list" ls))))
(error 'assoc "malformed alist" ls)))
(if (null? h)
#f
(error 'assoc "not a proper list" ls))))])
(lambda (x ls)
(race x ls ls ls))))
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(module (remq remv remove remp filter)
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(define-syntax define-remover
(syntax-rules ()
[(_ name cmp check)
(define name
(letrec ([race
(lambda (h t ls x)
(if (pair? h)
(if (cmp ($car h) x)
(let ([h ($cdr h)])
(if (pair? h)
(if (not (eq? h t))
(if (cmp ($car h) x)
(race ($cdr h) ($cdr t) ls x)
(cons ($car h) (race ($cdr h) ($cdr t) ls x)))
(error 'name "circular list" ls))
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(if (null? h)
'()
(error 'name "not a proper list" ls))))
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(let ([a0 ($car h)] [h ($cdr h)])
(if (pair? h)
(if (not (eq? h t))
(if (cmp ($car h) x)
(cons a0 (race ($cdr h) ($cdr t) ls x))
(cons* a0 ($car h) (race ($cdr h) ($cdr t) ls x)))
(error 'name "circular list" ls))
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(if (null? h)
(list a0)
(error 'name "not a proper list" ls)))))
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(if (null? h)
'()
(error 'name "not a proper list" ls))))])
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(lambda (x ls)
(check x ls)
(race ls ls ls x))))]))
(define-remover remq eq? (lambda (x ls) #t))
(define-remover remv eqv? (lambda (x ls) #t))
(define-remover remove equal? (lambda (x ls) #t))
(define-remover remp (lambda (elt p) (p elt))
(lambda (x ls)
(unless (procedure? x)
(error 'remp "not a procedure" x))))
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(define-remover filter (lambda (elt p) (not (p elt)))
(lambda (x ls)
(unless (procedure? x)
(error 'filter "not a procedure" x)))))
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(module (map)
(define who 'map)
(define len
(lambda (h t n)
(if (pair? h)
(let ([h ($cdr h)])
(if (pair? h)
(if (eq? h t)
(error who "circular list")
(len ($cdr h) ($cdr t) ($fx+ n 2)))
(if (null? h)
($fxadd1 n)
(error who "improper list"))))
(if (null? h)
n
(error who "improper list")))))
(define map1
(lambda (f a d n)
(cond
[(pair? d)
(if ($fxzero? n)
(error who "list was altered!")
(cons (f a)
(map1 f ($car d) ($cdr d) ($fxsub1 n))))]
[(null? d)
(if ($fxzero? n)
(cons (f a) '())
(error who "list was altered"))]
[else (error who "list was altered")])))
(define map2
(lambda (f a1 a2 d1 d2 n)
(cond
[(pair? d1)
(cond
[(pair? d2)
(if ($fxzero? n)
(error who "list was altered")
(cons (f a1 a2)
(map2 f
($car d1) ($car d2)
($cdr d1) ($cdr d2)
($fxsub1 n))))]
[else (error who "length mismatch")])]
[(null? d1)
(cond
[(null? d2)
(if ($fxzero? n)
(cons (f a1 a2) '())
(error who "list was altered"))]
[else (error who "length mismatch")])]
[else (error who "list was altered")])))
(define cars
(lambda (ls*)
(cond
[(null? ls*) '()]
[else
(let ([a (car ls*)])
(cond
[(pair? a)
(cons (car a) (cars (cdr ls*)))]
[else
(error 'map "length mismatch")]))])))
(define cdrs
(lambda (ls*)
(cond
[(null? ls*) '()]
[else
(let ([a (car ls*)])
(cond
[(pair? a)
(cons (cdr a) (cdrs (cdr ls*)))]
[else
(error 'map "length mismatch")]))])))
(define mapm
(lambda (f ls ls* n)
(cond
[(null? ls)
(if (andmap null? ls*)
(if (fxzero? n)
'()
(error 'map "lists were mutated during operation"))
(error 'map "length mismatch"))]
[(fxzero? n)
(error 'map "lists were mutated during operation")]
[else
(cons
(apply f (car ls) (cars ls*))
(mapm f (cdr ls) (cdrs ls*) (fxsub1 n)))])))
(define map
(case-lambda
[(f ls)
(unless (procedure? f)
(error who "not a procedure" f))
(cond
[(pair? ls)
(let ([d ($cdr ls)])
(map1 f ($car ls) d (len d d 0)))]
[(null? ls) '()]
[else (error who "improper list")])]
[(f ls ls2)
(unless (procedure? f)
(error who "not a procedure" f))
(cond
[(pair? ls)
(if (pair? ls2)
(let ([d ($cdr ls)])
(map2 f ($car ls) ($car ls2) d ($cdr ls2) (len d d 0)))
(error who "length mismatch"))]
[(null? ls)
(if (null? ls2)
'()
(error who "length mismatch"))]
[else (error who "not a list")])]
[(f ls . ls*)
(unless (procedure? f)
(error who "not a procedure" f))
(cond
[(pair? ls)
(let ([n (len ls ls 0)])
(mapm f ls ls* n))]
[(null? ls)
(if (andmap null? ls*)
'()
(error who "length mismatch"))])])))
(module (for-each)
(define who 'for-each)
(define len
(lambda (h t n)
(if (pair? h)
(let ([h ($cdr h)])
(if (pair? h)
(if (eq? h t)
(error who "circular list")
(len ($cdr h) ($cdr t) ($fx+ n 2)))
(if (null? h)
($fxadd1 n)
(error who "improper list"))))
(if (null? h)
n
(error who "improper list")))))
(define for-each1
(lambda (f a d n)
(cond
[(pair? d)
(if ($fxzero? n)
(error who "list was altered!")
(begin
(f a)
(for-each1 f ($car d) ($cdr d) ($fxsub1 n))))]
[(null? d)
(if ($fxzero? n)
(f a)
(error who "list was altered"))]
[else (error who "list was altered")])))
(define for-each2
(lambda (f a1 a2 d1 d2 n)
(cond
[(pair? d1)
(cond
[(pair? d2)
(if ($fxzero? n)
(error who "list was altered")
(begin
(f a1 a2)
(for-each2 f
($car d1) ($car d2)
($cdr d1) ($cdr d2)
($fxsub1 n))))]
[else (error who "length mismatch")])]
[(null? d1)
(cond
[(null? d2)
(if ($fxzero? n)
(f a1 a2)
(error who "list was altered"))]
[else (error who "length mismatch")])]
[else (error who "list was altered")])))
(define for-each
(case-lambda
[(f ls)
(unless (procedure? f)
(error who "not a procedure" f))
(cond
[(pair? ls)
(let ([d ($cdr ls)])
(for-each1 f ($car ls) d (len d d 0)))]
[(null? ls) (void)]
[else (error who "improper list")])]
[(f ls ls2)
(unless (procedure? f)
(error who "not a procedure" f))
(cond
[(pair? ls)
(if (pair? ls2)
(let ([d ($cdr ls)])
(for-each2 f
($car ls) ($car ls2) d ($cdr ls2) (len d d 0)))
(error who "length mismatch"))]
[(null? ls)
(if (null? ls2)
(void)
(error who "length mismatch"))]
[else (error who "not a list")])]
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[(f ls . ls*)
(unless (procedure? f)
(error 'for-each "not a procedure" f))
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(unless (list? ls)
(error 'for-each "not a list" ls))
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(let ([n (length ls)])
(for-each
(lambda (x)
(unless (and (list? x) (= (length x) n))
(error 'for-each "not a list" x)))
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ls*)
(let loop ([n (length ls)] [ls ls] [ls* ls*])
(cond
[($fx= n 0)
(unless (and (null? ls) (andmap null? ls*))
(error 'for-each "list modified" f))]
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[else
(unless (and (pair? ls) (andmap pair? ls*))
(error 'for-each "list modified" f))
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(apply f (car ls) (map car ls*))
(loop (fx- n 1) (cdr ls) (map cdr ls*))])))])))
(module (andmap)
(define who 'andmap)
(define len
(lambda (h t n)
(if (pair? h)
(let ([h ($cdr h)])
(if (pair? h)
(if (eq? h t)
(error who "circular list")
(len ($cdr h) ($cdr t) ($fx+ n 2)))
(if (null? h)
($fxadd1 n)
(error who "improper list"))))
(if (null? h)
n
(error who "improper list")))))
(define andmap1
(lambda (f a d n)
(cond
[(pair? d)
(if ($fxzero? n)
(error who "list was altered!")
(and (f a)
(andmap1 f ($car d) ($cdr d) ($fxsub1 n))))]
[(null? d)
(if ($fxzero? n)
(f a)
(error who "list was altered"))]
[else (error who "list was altered")])))
(define andmap2
(lambda (f a1 a2 d1 d2 n)
(cond
[(pair? d1)
(cond
[(pair? d2)
(if ($fxzero? n)
(error who "list was altered")
(and
(f a1 a2)
(andmap2 f
($car d1) ($car d2)
($cdr d1) ($cdr d2)
($fxsub1 n))))]
[else (error who "length mismatch")])]
[(null? d1)
(cond
[(null? d2)
(if ($fxzero? n)
(f a1 a2)
(error who "list was altered"))]
[else (error who "length mismatch")])]
[else (error who "list was altered")])))
(define andmap
(case-lambda
[(f ls)
(unless (procedure? f)
(error who "not a procedure" f))
(cond
[(pair? ls)
(let ([d ($cdr ls)])
(andmap1 f ($car ls) d (len d d 0)))]
[(null? ls) #t]
[else (error who "improper list")])]
[(f ls ls2)
(unless (procedure? f)
(error who "not a procedure" f))
(cond
[(pair? ls)
(if (pair? ls2)
(let ([d ($cdr ls)])
(andmap2 f
($car ls) ($car ls2) d ($cdr ls2) (len d d 0)))
(error who "length mismatch"))]
[(null? ls)
(if (null? ls2)
#t
(error who "length mismatch"))]
[else (error who "not a list")])]
[(f ls . ls*)
(unless (procedure? f)
(error who "not a procedure" f))
(error who "vararg not yet supported")])))
(module (ormap)
(define who 'ormap)
(define len
(lambda (h t n)
(if (pair? h)
(let ([h ($cdr h)])
(if (pair? h)
(if (eq? h t)
(error who "circular list")
(len ($cdr h) ($cdr t) ($fx+ n 2)))
(if (null? h)
($fxadd1 n)
(error who "improper list"))))
(if (null? h)
n
(error who "improper list")))))
(define ormap1
(lambda (f a d n)
(cond
[(pair? d)
(if ($fxzero? n)
(error who "list was altered!")
(or (f a)
(ormap1 f ($car d) ($cdr d) ($fxsub1 n))))]
[(null? d)
(if ($fxzero? n)
(f a)
(error who "list was altered"))]
[else (error who "list was altered")])))
(define ormap
(case-lambda
[(f ls)
(unless (procedure? f)
(error who "not a procedure" f))
(cond
[(pair? ls)
(let ([d ($cdr ls)])
(ormap1 f ($car ls) d (len d d 0)))]
[(null? ls) #f]
[else (error who "improper list")])]
[_ (error who "vararg not supported yet")])))
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(define partition
(letrec ([race
(lambda (h t ls p)
(if (pair? h)
(let ([a0 ($car h)] [h ($cdr h)])
(if (pair? h)
(if (eq? h t)
(error 'partition "circular list" ls)
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(let ([a1 ($car h)])
(let-values ([(a* b*) (race ($cdr h) ($cdr t) ls p)])
(if (p a0)
(if (p a1)
(values (cons* a0 a1 a*) b*)
(values (cons a0 a*) (cons a1 b*)))
(if (p a1)
(values (cons a1 a*) (cons a0 b*))
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(values a* (cons* a0 a1 b*)))))))
(if (null? h)
(if (p a0)
(values (list a0) '())
(values '() (list a0)))
(error 'parititon "not a proper list" ls))))
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(if (null? h)
(values '() '())
(error 'parition "not a proper list" ls))))])
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(lambda (p ls)
(unless (procedure? p)
(error 'partition "not a procedure" p))
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(race ls ls ls p))))
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(define-syntax define-iterator
(syntax-rules ()
[(_ name combine)
(module (name)
(define who 'name)
(define (null*? ls)
(or (null? ls) (and (null? (car ls)) (null*? (cdr ls)))))
(define (err* ls*)
(if (null? ls*)
(error who "length mismatch")
(if (list? (car ls*))
(err* (cdr ls*))
(error who "not a proper list" (car ls*)))))
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(define (cars+cdrs ls ls*)
(cond
[(null? ls) (values '() '())]
[else
(let ([a (car ls)])
(if (pair? a)
(let-values ([(cars cdrs) (cars+cdrs (cdr ls) (cdr ls*))])
(values (cons (car a) cars) (cons (cdr a) cdrs)))
(if (list? (car ls*))
(error who "length mismatch")
(error who "not a proper list" (car ls*)))))]))
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(define (loop1 f a h t ls)
(if (pair? h)
(let ([b (car h)] [h (cdr h)])
(combine (f a)
(if (pair? h)
(if (eq? h t)
(error who "circular" ls)
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(let ([c (car h)] [h (cdr h)])
(combine (f b) (loop1 f c h (cdr t) ls))))
(if (null? h)
(f b)
(combine (f b) (error who "not a proper list" ls))))))
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(if (null? h)
(f a)
(combine (f a) (error who "not a proper list" ls)))))
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(define (loopn f a a* h h* t ls ls*)
(if (pair? h)
(let-values ([(b* h*) (cars+cdrs h* ls*)])
(let ([b (car h)] [h (cdr h)])
(combine (apply f a a*)
(if (pair? h)
(if (eq? h t)
(error who "circular" ls)
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(let-values ([(c* h*) (cars+cdrs h* ls*)])
(let ([c (car h)] [h (cdr h)])
(combine (apply f b b*)
(loopn f c c* h h* (cdr t) ls ls*)))))
(if (and (null? h) (null*? h*))
(apply f b b*)
(combine (apply f b b*) (err* (cons ls ls*))))))))
(if (and (null? h) (null*? h*))
(apply f a a*)
(combine (apply f a a*) (err* (cons ls ls*))))))
(define name
(case-lambda
[(f ls)
(unless (procedure? f)
(error who "not a procedure" f))
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(if (pair? ls)
(loop1 f (car ls) (cdr ls) (cdr ls) ls)
(if (null? ls)
(combine)
(error who "not a list" ls)))]
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[(f ls . ls*)
(unless (procedure? f)
(error who "not a procedure" f))
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(if (pair? ls)
(let-values ([(cars cdrs) (cars+cdrs ls* ls*)])
(loopn f (car ls) cars (cdr ls) cdrs (cdr ls) ls ls*))
(if (and (null? ls) (null*? ls*))
(combine)
(err* ls*)))])))]))
(define-iterator for-all and)
(define-iterator exists or)
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(module (fold-left)
(define who 'fold-left)
(define (null*? ls)
(or (null? ls) (and (null? (car ls)) (null*? (cdr ls)))))
(define (err* ls*)
(if (null? ls*)
(error who "length mismatch")
(if (list? (car ls*))
(err* (cdr ls*))
(error who "not a proper list" (car ls*)))))
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(define (cars+cdrs ls ls*)
(cond
[(null? ls) (values '() '())]
[else
(let ([a (car ls)])
(if (pair? a)
(let-values ([(cars cdrs) (cars+cdrs (cdr ls) (cdr ls*))])
(values (cons (car a) cars) (cons (cdr a) cdrs)))
(if (list? (car ls*))
(error who "length mismatch")
(error who "not a proper list" (car ls*)))))]))
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(define (loop1 f nil h t ls)
(if (pair? h)
(let ([a (car h)] [h (cdr h)])
(if (pair? h)
(if (eq? h t)
(error who "circular" ls)
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(let ([b (car h)] [h (cdr h)] [t (cdr t)])
(loop1 f (f (f nil a) b) h t ls)))
(if (null? h)
(f nil a)
(error who "not a proper list" ls))))
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(if (null? h)
nil
(error who "not a proper list" ls))))
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(define (loopn f nil h h* t ls ls*)
(if (pair? h)
(let-values ([(a* h*) (cars+cdrs h* ls*)])
(let ([a (car h)] [h (cdr h)])
(if (pair? h)
(if (eq? h t)
(error who "circular" ls)
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(let-values ([(b* h*) (cars+cdrs h* ls*)])
(let ([b (car h)] [h (cdr h)] [t (cdr t)])
(loopn f
(apply f (apply f nil a a*) b b*)
h h* t ls ls*))))
(if (and (null? h) (null*? h*))
(apply f nil a a*)
(err* (cons ls ls*))))))
(if (and (null? h) (null*? h*))
nil
(err* (cons ls ls*)))))
(define fold-left
(case-lambda
[(f nil ls)
(unless (procedure? f)
(error who "not a procedure" f))
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(loop1 f nil ls ls ls)]
[(f nil ls . ls*)
(unless (procedure? f)
(error who "not a procedure" f))
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(loopn f nil ls ls* ls ls ls*)])))
(module (fold-right)
(define who 'fold-right)
(define (null*? ls)
(or (null? ls) (and (null? (car ls)) (null*? (cdr ls)))))
(define (err* ls*)
(if (null? ls*)
(error who "length mismatch")
(if (list? (car ls*))
(err* (cdr ls*))
(error who "not a proper list" (car ls*)))))
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(define (cars+cdrs ls ls*)
(cond
[(null? ls) (values '() '())]
[else
(let ([a (car ls)])
(if (pair? a)
(let-values ([(cars cdrs) (cars+cdrs (cdr ls) (cdr ls*))])
(values (cons (car a) cars) (cons (cdr a) cdrs)))
(if (list? (car ls*))
(error who "length mismatch")
(error who "not a proper list" (car ls*)))))]))
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(define (loop1 f nil h t ls)
(if (pair? h)
(let ([a (car h)] [h (cdr h)])
(if (pair? h)
(if (eq? h t)
(error who "circular" ls)
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(let ([b (car h)] [h (cdr h)] [t (cdr t)])
(f a (f b (loop1 f nil h t ls)))))
(if (null? h)
(f a nil)
(error who "not a proper list" ls))))
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(if (null? h)
nil
(error who "not a proper list" ls))))
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(define (loopn f nil h h* t ls ls*)
(if (pair? h)
(let-values ([(a* h*) (cars+cdrs h* ls*)])
(let ([a (car h)] [h (cdr h)])
(if (pair? h)
(if (eq? h t)
(error who "circular" ls)
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(let-values ([(b* h*) (cars+cdrs h* ls*)])
(let ([b (car h)] [h (cdr h)] [t (cdr t)])
(apply f a
(append a*
(list
(apply f
b (append b*
(list (loopn f nil h h* t ls ls*))))))))))
(if (and (null? h) (null*? h*))
(apply f a (append a* (list nil)))
(err* (cons ls ls*))))))
(if (and (null? h) (null*? h*))
nil
(err* (cons ls ls*)))))
(define fold-right
(case-lambda
[(f nil ls)
(unless (procedure? f)
(error who "not a procedure" f))
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(loop1 f nil ls ls ls)]
[(f nil ls . ls*)
(unless (procedure? f)
(error who "not a procedure" f))
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(loopn f nil ls ls* ls ls ls*)]
)))
)