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#!r6rs
; <PLAINTEXT>
; Examples for Eager Comprehensions in [outer..inner|expr]-Convention
; ===================================================================
;
; sebastian.egner@philips.com, Eindhoven, The Netherlands, 25-Apr-2005.
; Scheme R5RS (incl. macros), SRFI-23 (error).
;
; Running the examples in Scheme48 (version 1.1):
; ,open srfi-23
; ,load ec.scm
; (define my-open-output-file open-output-file)
; (define my-call-with-input-file call-with-input-file)
; ,load examples.scm
;
; Running the examples in PLT/DrScheme (version 208):
; (load "ec.scm")
; (define (my-open-output-file filename)
; (open-output-file filename 'replace 'text) )
; (define (my-call-with-input-file filename thunk)
; (call-with-input-file filename thunk 'text) )
; (load "examples.scm")
;
; Running the examples in SCM (version 5d7):
; (require 'macro) (require 'record)
; (load "ec.scm")
; (define my-open-output-file open-output-file)
; (define my-call-with-input-file call-with-input-file)
; (load "examples.scm")
(import
(except (rnrs) error)
(rnrs mutable-strings)
(surfage s42 eager-comprehensions)
(surfage s23 error))
(define (my-open-output-file filename)
(open-file-output-port filename
(file-options no-fail)
'block
(native-transcoder)))
(define (my-call-with-input-file filename thunk)
(call-with-input-file filename thunk))
; Tools for checking results
; ==========================
(define (my-equal? x y)
(cond
((or (boolean? x)
(null? x)
(symbol? x)
(char? x)
(input-port? x)
(output-port? x) )
(eqv? x y) )
((string? x)
(and (string? y) (string=? x y)) )
((vector? x)
(and (vector? y)
(my-equal? (vector->list x) (vector->list y)) ))
((pair? x)
(and (pair? y)
(my-equal? (car x) (car y))
(my-equal? (cdr x) (cdr y)) ))
((real? x)
(and (real? y)
(eqv? (exact? x) (exact? y))
(if (exact? x)
(= x y)
(< (abs (- x y)) (/ 1 (expt 10 6))) ))) ; will do here
(else
(error "unrecognized type" x) )))
(define my-check-correct 0)
(define my-check-wrong 0)
(define-syntax my-check
(syntax-rules (=>)
((my-check ec => desired-result)
(begin
(newline)
(write (quote ec))
(newline)
(let ((actual-result ec))
(display " => ")
(write actual-result)
(if (my-equal? actual-result desired-result)
(begin
(display " ; correct")
(set! my-check-correct (+ my-check-correct 1)) )
(begin
(display " ; *** wrong ***, desired result:")
(newline)
(display " => ")
(write desired-result)
(set! my-check-wrong (+ my-check-wrong 1)) ))
(newline) )))))
; ==========================================================================
; do-ec
; ==========================================================================
(my-check
(let ((x 0)) (do-ec (set! x (+ x 1))) x)
=> 1)
(my-check
(let ((x 0)) (do-ec (:range i 10) (set! x (+ x 1))) x)
=> 10)
(my-check
(let ((x 0)) (do-ec (:range n 10) (:range k n) (set! x (+ x 1))) x)
=> 45)
; ==========================================================================
; list-ec and basic qualifiers
; ==========================================================================
(my-check (list-ec 1) => '(1))
(my-check (list-ec (:range i 4) i) => '(0 1 2 3))
(my-check (list-ec (:range n 3) (:range k (+ n 1)) (list n k))
=> '((0 0) (1 0) (1 1) (2 0) (2 1) (2 2)) )
(my-check
(list-ec (:range n 5) (if (even? n)) (:range k (+ n 1)) (list n k))
=> '((0 0) (2 0) (2 1) (2 2) (4 0) (4 1) (4 2) (4 3) (4 4)) )
(my-check
(list-ec (:range n 5) (not (even? n)) (:range k (+ n 1)) (list n k))
=> '((1 0) (1 1) (3 0) (3 1) (3 2) (3 3)) )
(my-check
(list-ec (:range n 5)
(and (even? n) (> n 2))
(:range k (+ n 1))
(list n k) )
=> '((4 0) (4 1) (4 2) (4 3) (4 4)) )
(my-check
(list-ec (:range n 5)
(or (even? n) (> n 3))
(:range k (+ n 1))
(list n k) )
=> '((0 0) (2 0) (2 1) (2 2) (4 0) (4 1) (4 2) (4 3) (4 4)) )
(my-check
(let ((x 0)) (list-ec (:range n 10) (begin (set! x (+ x 1))) n) x)
=> 10 )
(my-check
(list-ec (nested (:range n 3) (:range k n)) k)
=> '(0 0 1) )
; ==========================================================================
; Other comprehensions
; ==========================================================================
(my-check (append-ec '(a b)) => '(a b))
(my-check (append-ec (:range i 0) '(a b)) => '())
(my-check (append-ec (:range i 1) '(a b)) => '(a b))
(my-check (append-ec (:range i 2) '(a b)) => '(a b a b))
(my-check (string-ec #\a) => (string #\a))
(my-check (string-ec (:range i 0) #\a) => "")
(my-check (string-ec (:range i 1) #\a) => "a")
(my-check (string-ec (:range i 2) #\a) => "aa")
(my-check (string-append-ec "ab") => "ab")
(my-check (string-append-ec (:range i 0) "ab") => "")
(my-check (string-append-ec (:range i 1) "ab") => "ab")
(my-check (string-append-ec (:range i 2) "ab") => "abab")
(my-check (vector-ec 1) => (vector 1))
(my-check (vector-ec (:range i 0) i) => (vector))
(my-check (vector-ec (:range i 1) i) => (vector 0))
(my-check (vector-ec (:range i 2) i) => (vector 0 1))
(my-check (vector-of-length-ec 1 1) => (vector 1))
(my-check (vector-of-length-ec 0 (:range i 0) i) => (vector))
(my-check (vector-of-length-ec 1 (:range i 1) i) => (vector 0))
(my-check (vector-of-length-ec 2 (:range i 2) i) => (vector 0 1))
(my-check (sum-ec 1) => 1)
(my-check (sum-ec (:range i 0) i) => 0)
(my-check (sum-ec (:range i 1) i) => 0)
(my-check (sum-ec (:range i 2) i) => 1)
(my-check (sum-ec (:range i 3) i) => 3)
(my-check (product-ec 1) => 1)
(my-check (product-ec (:range i 1 0) i) => 1)
(my-check (product-ec (:range i 1 1) i) => 1)
(my-check (product-ec (:range i 1 2) i) => 1)
(my-check (product-ec (:range i 1 3) i) => 2)
(my-check (product-ec (:range i 1 4) i) => 6)
(my-check (min-ec 1) => 1)
(my-check (min-ec (:range i 1) i) => 0)
(my-check (min-ec (:range i 2) i) => 0)
(my-check (max-ec 1) => 1)
(my-check (max-ec (:range i 1) i) => 0)
(my-check (max-ec (:range i 2) i) => 1)
(my-check (first-ec #f 1) => 1)
(my-check (first-ec #f (:range i 0) i) => #f)
(my-check (first-ec #f (:range i 1) i) => 0)
(my-check (first-ec #f (:range i 2) i) => 0)
(my-check
(let ((last-i -1))
(first-ec #f (:range i 10) (begin (set! last-i i)) i)
last-i )
=> 0 )
(my-check (last-ec #f 1) => 1)
(my-check (last-ec #f (:range i 0) i) => #f)
(my-check (last-ec #f (:range i 1) i) => 0)
(my-check (last-ec #f (:range i 2) i) => 1)
(my-check (any?-ec #f) => #f)
(my-check (any?-ec #t) => #t)
(my-check (any?-ec (:range i 2 2) (even? i)) => #f)
(my-check (any?-ec (:range i 2 3) (even? i)) => #t)
(my-check (every?-ec #f) => #f)
(my-check (every?-ec #t) => #t)
(my-check (every?-ec (:range i 2 2) (even? i)) => #t)
(my-check (every?-ec (:range i 2 3) (even? i)) => #t)
(my-check (every?-ec (:range i 2 4) (even? i)) => #f)
(my-check
(let ((sum-sqr (lambda (x result) (+ result (* x x)))))
(fold-ec 0 (:range i 10) i sum-sqr) )
=> 285 )
(my-check
(let ((minus-1 (lambda (x) (- x 1)))
(sum-sqr (lambda (x result) (+ result (* x x)))))
(fold3-ec (error "wrong") (:range i 10) i minus-1 sum-sqr) )
=> 284 )
(my-check
(fold3-ec 'infinity (:range i 0) i min min)
=> 'infinity )
; ==========================================================================
; Typed generators
; ==========================================================================
(my-check (list-ec (:list x '()) x) => '())
(my-check (list-ec (:list x '(1)) x) => '(1))
(my-check (list-ec (:list x '(1 2 3)) x) => '(1 2 3))
(my-check (list-ec (:list x '(1) '(2)) x) => '(1 2))
(my-check (list-ec (:list x '(1) '(2) '(3)) x) => '(1 2 3))
(my-check (list-ec (:string c "") c) => '())
(my-check (list-ec (:string c "1") c) => '(#\1))
(my-check (list-ec (:string c "123") c) => '(#\1 #\2 #\3))
(my-check (list-ec (:string c "1" "2") c) => '(#\1 #\2))
(my-check (list-ec (:string c "1" "2" "3") c) => '(#\1 #\2 #\3))
(my-check (list-ec (:vector x (vector)) x) => '())
(my-check (list-ec (:vector x (vector 1)) x) => '(1))
(my-check (list-ec (:vector x (vector 1 2 3)) x) => '(1 2 3))
(my-check (list-ec (:vector x (vector 1) (vector 2)) x) => '(1 2))
(my-check
(list-ec (:vector x (vector 1) (vector 2) (vector 3)) x)
=> '(1 2 3))
(my-check (list-ec (:range x -2) x) => '())
(my-check (list-ec (:range x -1) x) => '())
(my-check (list-ec (:range x 0) x) => '())
(my-check (list-ec (:range x 1) x) => '(0))
(my-check (list-ec (:range x 2) x) => '(0 1))
(my-check (list-ec (:range x 0 3) x) => '(0 1 2))
(my-check (list-ec (:range x 1 3) x) => '(1 2))
(my-check (list-ec (:range x -2 -1) x) => '(-2))
(my-check (list-ec (:range x -2 -2) x) => '())
(my-check (list-ec (:range x 1 5 2) x) => '(1 3))
(my-check (list-ec (:range x 1 6 2) x) => '(1 3 5))
(my-check (list-ec (:range x 5 1 -2) x) => '(5 3))
(my-check (list-ec (:range x 6 1 -2) x) => '(6 4 2))
(my-check (list-ec (:real-range x 0.0 3.0) x) => '(0. 1. 2.))
(my-check (list-ec (:real-range x 0 3.0) x) => '(0. 1. 2.))
(my-check (list-ec (:real-range x 0 3 1.0) x) => '(0. 1. 2.))
(my-check
(string-ec (:char-range c #\a #\z) c)
=> "abcdefghijklmnopqrstuvwxyz" )
(my-check
(begin
(let ((f (my-open-output-file "tmp1")))
(do-ec (:range n 10) (begin (write n f) (newline f)))
(close-output-port f))
(my-call-with-input-file "tmp1"
(lambda (port) (list-ec (:port x port read) x)) ))
=> (list-ec (:range n 10) n) )
(my-check
(begin
(let ((f (my-open-output-file "tmp1")))
(do-ec (:range n 10) (begin (write n f) (newline f)))
(close-output-port f))
(my-call-with-input-file "tmp1"
(lambda (port) (list-ec (:port x port) x)) ))
=> (list-ec (:range n 10) n) )
; ==========================================================================
; The special generators :do :let :parallel :while :until
; ==========================================================================
(my-check (list-ec (:do ((i 0)) (< i 4) ((+ i 1))) i) => '(0 1 2 3))
(my-check
(list-ec
(:do (let ((x 'x)))
((i 0))
(< i 4)
(let ((j (- 10 i))))
#t
((+ i 1)) )
j )
=> '(10 9 8 7) )
(my-check (list-ec (:let x 1) x) => '(1))
(my-check (list-ec (:let x 1) (:let y (+ x 1)) y) => '(2))
(my-check (list-ec (:let x 1) (:let x (+ x 1)) x) => '(2))
(my-check
(list-ec (:parallel (:range i 1 10) (:list x '(a b c))) (list i x))
=> '((1 a) (2 b) (3 c)) )
(my-check
(list-ec (:while (:range i 1 10) (< i 5)) i)
=> '(1 2 3 4) )
(my-check
(list-ec (:until (:range i 1 10) (>= i 5)) i)
=> '(1 2 3 4 5) )
; with generator that might use inner bindings
(my-check
(list-ec (:while (:list i '(1 2 3 4 5 6 7 8 9)) (< i 5)) i)
=> '(1 2 3 4) )
; Was broken in original reference implementation as pointed
; out by sunnan@handgranat.org on 24-Apr-2005 comp.lang.scheme.
; Refer to http://groups-beta.google.com/group/comp.lang.scheme/
; browse_thread/thread/f5333220eaeeed66/75926634cf31c038#75926634cf31c038
(my-check
(list-ec (:until (:list i '(1 2 3 4 5 6 7 8 9)) (>= i 5)) i)
=> '(1 2 3 4 5) )
; combine :while/:until and :parallel
(my-check
(list-ec (:while (:parallel (:range i 1 10)
(:list j '(1 2 3 4 5 6 7 8 9)))
(< i 5))
(list i j))
=> '((1 1) (2 2) (3 3) (4 4)))
(my-check
(list-ec (:until (:parallel (:range i 1 10)
(:list j '(1 2 3 4 5 6 7 8 9)))
(>= i 5))
(list i j))
=> '((1 1) (2 2) (3 3) (4 4) (5 5)))
; check that :while/:until really stop the generator
(my-check
(let ((n 0))
(do-ec (:while (:range i 1 10) (begin (set! n (+ n 1)) (< i 5)))
(if #f #f))
n)
=> 5)
(my-check
(let ((n 0))
(do-ec (:until (:range i 1 10) (begin (set! n (+ n 1)) (>= i 5)))
(if #f #f))
n)
=> 5)
(my-check
(let ((n 0))
(do-ec (:while (:parallel (:range i 1 10)
(:do () (begin (set! n (+ n 1)) #t) ()))
(< i 5))
(if #f #f))
n)
=> 5)
(my-check
(let ((n 0))
(do-ec (:until (:parallel (:range i 1 10)
(:do () (begin (set! n (+ n 1)) #t) ()))
(>= i 5))
(if #f #f))
n)
=> 5)
; ==========================================================================
; The dispatching generator
; ==========================================================================
(my-check (list-ec (: c '(a b)) c) => '(a b))
(my-check (list-ec (: c '(a b) '(c d)) c) => '(a b c d))
(my-check (list-ec (: c "ab") c) => '(#\a #\b))
(my-check (list-ec (: c "ab" "cd") c) => '(#\a #\b #\c #\d))
(my-check (list-ec (: c (vector 'a 'b)) c) => '(a b))
(my-check (list-ec (: c (vector 'a 'b) (vector 'c)) c) => '(a b c))
(my-check (list-ec (: i 0) i) => '())
(my-check (list-ec (: i 1) i) => '(0))
(my-check (list-ec (: i 10) i) => '(0 1 2 3 4 5 6 7 8 9))
(my-check (list-ec (: i 1 2) i) => '(1))
(my-check (list-ec (: i 1 2 3) i) => '(1))
(my-check (list-ec (: i 1 9 3) i) => '(1 4 7))
(my-check (list-ec (: i 0.0 1.0 0.2) i) => '(0. 0.2 0.4 0.6 0.8))
(my-check (list-ec (: c #\a #\c) c) => '(#\a #\b #\c))
(my-check
(begin
(let ((f (my-open-output-file "tmp1")))
(do-ec (:range n 10) (begin (write n f) (newline f)))
(close-output-port f))
(my-call-with-input-file "tmp1"
(lambda (port) (list-ec (: x port read) x)) ))
=> (list-ec (:range n 10) n) )
(my-check
(begin
(let ((f (my-open-output-file "tmp1")))
(do-ec (:range n 10) (begin (write n f) (newline f)))
(close-output-port f))
(my-call-with-input-file "tmp1"
(lambda (port) (list-ec (: x port) x)) ))
=> (list-ec (:range n 10) n) )
; ==========================================================================
; With index variable
; ==========================================================================
(my-check (list-ec (:list c (index i) '(a b)) (list c i)) => '((a 0) (b 1)))
(my-check (list-ec (:string c (index i) "a") (list c i)) => '((#\a 0)))
(my-check (list-ec (:vector c (index i) (vector 'a)) (list c i)) => '((a 0)))
(my-check
(list-ec (:range i (index j) 0 -3 -1) (list i j))
=> '((0 0) (-1 1) (-2 2)) )
(my-check
(list-ec (:real-range i (index j) 0 1 0.2) (list i j))
=> '((0. 0) (0.2 1) (0.4 2) (0.6 3) (0.8 4)) )
(my-check
(list-ec (:char-range c (index i) #\a #\c) (list c i))
=> '((#\a 0) (#\b 1) (#\c 2)) )
(my-check
(list-ec (: x (index i) '(a b c d)) (list x i))
=> '((a 0) (b 1) (c 2) (d 3)) )
(my-check
(begin
(let ((f (my-open-output-file "tmp1")))
(do-ec (:range n 10) (begin (write n f) (newline f)))
(close-output-port f))
(my-call-with-input-file "tmp1"
(lambda (port) (list-ec (: x (index i) port) (list x i))) ))
=> '((0 0) (1 1) (2 2) (3 3) (4 4) (5 5) (6 6) (7 7) (8 8) (9 9)) )
; ==========================================================================
; The examples from the SRFI document
; ==========================================================================
; from Abstract
(my-check (list-ec (: i 5) (* i i)) => '(0 1 4 9 16))
(my-check
(list-ec (: n 1 4) (: i n) (list n i))
=> '((1 0) (2 0) (2 1) (3 0) (3 1) (3 2)) )
; from Generators
(my-check
(list-ec (: x (index i) "abc") (list x i))
=> '((#\a 0) (#\b 1) (#\c 2)) )
(my-check
(list-ec (:string c (index i) "a" "b") (cons c i))
=> '((#\a . 0) (#\b . 1)) )
; ==========================================================================
; Little Shop of Horrors
; ==========================================================================
(my-check (list-ec (:range x 5) (:range x x) x) => '(0 0 1 0 1 2 0 1 2 3))
(my-check (list-ec (:list x '(2 "23" (4))) (: y x) y) => '(0 1 #\2 #\3 4))
(my-check
(list-ec (:parallel (:integers x)
(:do ((i 10)) (< x i) ((- i 1))))
(list x i))
=> '((0 10) (1 9) (2 8) (3 7) (4 6)) )
; ==========================================================================
; Less artificial examples
; ==========================================================================
(define (factorial n) ; n * (n-1) * .. * 1 for n >= 0
(product-ec (:range k 2 (+ n 1)) k) )
(my-check (factorial 0) => 1)
(my-check (factorial 1) => 1)
(my-check (factorial 3) => 6)
(my-check (factorial 5) => 120)
(define (eratosthenes n) ; primes in {2..n-1} for n >= 1
(let ((p? (make-string n #\1)))
(do-ec (:range k 2 n)
(if (char=? (string-ref p? k) #\1))
(:range i (* 2 k) n k)
(string-set! p? i #\0) )
(list-ec (:range k 2 n) (if (char=? (string-ref p? k) #\1)) k) ))
(my-check
(eratosthenes 50)
=> '(2 3 5 7 11 13 17 19 23 29 31 37 41 43 47) )
(my-check
(length (eratosthenes 100000))
=> 9592 ) ; we expect 10^5/ln(10^5)
(define (pythagoras n) ; a, b, c s.t. 1 <= a <= b <= c <= n, a^2 + b^2 = c^2
(list-ec
(:let sqr-n (* n n))
(:range a 1 (+ n 1))
; (begin (display a) (display " "))
(:let sqr-a (* a a))
(:range b a (+ n 1))
(:let sqr-c (+ sqr-a (* b b)))
(if (<= sqr-c sqr-n))
(:range c b (+ n 1))
(if (= (* c c) sqr-c))
(list a b c) ))
(my-check
(pythagoras 15)
=> '((3 4 5) (5 12 13) (6 8 10) (9 12 15)) )
(my-check
(length (pythagoras 200))
=> 127 )
(define (qsort xs) ; stable
(if (null? xs)
'()
(let ((pivot (car xs)) (xrest (cdr xs)))
(append
(qsort (list-ec (:list x xrest) (if (< x pivot)) x))
(list pivot)
(qsort (list-ec (:list x xrest) (if (>= x pivot)) x)) ))))
(my-check
(qsort '(1 5 4 2 4 5 3 2 1 3))
=> '(1 1 2 2 3 3 4 4 5 5) )
(define (pi-BBP m) ; approx. of pi within 16^-m (Bailey-Borwein-Plouffe)
(sum-ec
(:range n 0 (+ m 1))
(:let n8 (* 8 n))
(* (- (/ 4 (+ n8 1))
(+ (/ 2 (+ n8 4))
(/ 1 (+ n8 5))
(/ 1 (+ n8 6))))
(/ 1 (expt 16 n)) )))
(my-check
(pi-BBP 5)
=> (/ 40413742330349316707 12864093722915635200) )
(define (read-lines filename) ; list of all lines
(my-call-with-input-file
filename
(lambda (port)
(list-ec (:port line port get-line) line) )))
(my-check
(begin
(let ((f (my-open-output-file "tmp1")))
(do-ec (:range n 10) (begin (write n f) (newline f)))
(close-output-port f))
(read-lines "tmp1") )
=> (list-ec (:char-range c #\0 #\9) (string c)) )
; ==========================================================================
; Summary
; ==========================================================================
(begin
(newline)
(newline)
(display "correct examples : ")
(display my-check-correct)
(newline)
(display "wrong examples : ")
(display my-check-wrong)
(newline)
(newline) )