Lisp newbie needs help

Discussion:

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B. Pym

2024-08-29 09:04:42 UTC

(defun my-test ()
(loop for number = (1+ (random 6))
as sum = number then (+ sum number)
until (= number 1)
do (format t "~&~D thrown. Sum: ~D" number sum)
finally (format t "~&One thrown.")))

Gauche Scheme

(use srfi-1) ;; unfold
(use srfi-27) ;; random-integer

(define (my-test)
(fold
(^(n sum) (print n " thrown. Sum: " (inc! sum n)) sum)
0
(cdr (unfold zero? ($ + 1 $) (^_ (random-integer 6)) -1)))
(print "One thrown."))

gosh> (my-test)
2 thrown. Sum: 2
2 thrown. Sum: 4
6 thrown. Sum: 10
One thrown.

gosh> (my-test)
One thrown.

Explanation of "unfold":

Function: unfold end-test key gen-next-seed seed :optional tail-gen

(unfold zero? (lambda(n) (+ 800 n)) (lambda(n) (- n 1)) 7)
===>
(807 806 805 804 803 802 801)

(unfold zero? (lambda(n) (+ 800 n)) (lambda(n) (- n 1)) 7
(lambda(n) (list "The number" n "ended the unfolding.")))
===>
(807 806 805 804 803 802 801 "The number" 0 "ended the unfolding.")

B. Pym

2024-08-29 09:29:31 UTC

Permalink

Post by B. Pym

(defun my-test ()
(loop for number = (1+ (random 6))
as sum = number then (+ sum number)
until (= number 1)
do (format t "~&~D thrown. Sum: ~D" number sum)
finally (format t "~&One thrown.")))

Gauche Scheme
(use srfi-1) ;; unfold
(use srfi-27) ;; random-integer
(define (my-test)
(fold
(^(n sum) (print n " thrown. Sum: " (inc! sum n)) sum)
0
(cdr (unfold zero? ($ + 1 $) (^_ (random-integer 6)) -1)))
(print "One thrown."))
gosh> (my-test)
2 thrown. Sum: 2
2 thrown. Sum: 4
6 thrown. Sum: 10
One thrown.
gosh> (my-test)
One thrown.
Function: unfold end-test key gen-next-seed seed :optional tail-gen
(unfold zero? (lambda(n) (+ 800 n)) (lambda(n) (- n 1)) 7)
===>
(807 806 805 804 803 802 801)
(unfold zero? (lambda(n) (+ 800 n)) (lambda(n) (- n 1)) 7
(lambda(n) (list "The number" n "ended the unfolding.")))
===>
(807 806 805 804 803 802 801 "The number" 0 "ended the unfolding.")

Using "do" is a bit tricky, but the result is shorter.

(define (my-test)
(do ((n #f (+ 1 (random-integer 6)))
(sum 0))
((eqv? 1 n) (print "One thrown."))
(if n (print n " thrown. Sum: " (inc! sum n)))))

B. Pym

2024-08-29 11:38:11 UTC

Permalink

Post by B. Pym

(defun my-test ()
(loop for number = (1+ (random 6))
as sum = number then (+ sum number)
until (= number 1)
do (format t "~&~D thrown. Sum: ~D" number sum)
finally (format t "~&One thrown.")))

Gauche Scheme
(use srfi-1) ;; unfold
(use srfi-27) ;; random-integer
(define (my-test)
(fold
(^(n sum) (print n " thrown. Sum: " (inc! sum n)) sum)
0
(cdr (unfold zero? ($ + 1 $) (^_ (random-integer 6)) -1)))
(print "One thrown."))
gosh> (my-test)
2 thrown. Sum: 2
2 thrown. Sum: 4
6 thrown. Sum: 10
One thrown.
gosh> (my-test)
One thrown.
Function: unfold end-test key gen-next-seed seed :optional tail-gen
(unfold zero? (lambda(n) (+ 800 n)) (lambda(n) (- n 1)) 7)
===>
(807 806 805 804 803 802 801)
(unfold zero? (lambda(n) (+ 800 n)) (lambda(n) (- n 1)) 7
(lambda(n) (list "The number" n "ended the unfolding.")))
===>
(807 806 805 804 803 802 801 "The number" 0 "ended the unfolding.")

Using "do" is a bit tricky, but the result is shorter.
(define (my-test)
(do ((n #f (+ 1 (random-integer 6)))
(sum 0))
((eqv? 1 n) (print "One thrown."))
(if n (print n " thrown. Sum: " (inc! sum n)))))

It seems to me that "do*" is more appropriate for this,
but this version is 2 characters longer!

(define (my-test)
(do* ((n #f (+ 1 (random-integer 6)))
(sum 0 (+ n sum)))
((eqv? 1 n) (print "One thrown."))
(if n (print n " thrown. Sum: " sum))))

I don't know why Common Lisp has "do*", but Gauche, Racket,
and Chicken Scheme don't.

Here's a version that I cobbled together. (A macro guru
may give us a better one.) "do" is to "do*" as "let" is
to "let*".

(define-syntax do*-aux
(syntax-rules ()
[(do* (inits ...) ((var update) ...) (test expr ...) stuff ...)
(let* (inits ...)
(if test
(begin expr ...)
(begin
(begin stuff ...)
(let loop ()
(begin (set! var update) ...)
(if test
(begin expr ...)
(begin stuff ...
(loop)))))))]))

(define-syntax do*
(syntax-rules (!!!)
[(do* !!! (inits ...) (updates ...)
((var init update) more ...) until body ...)
(do* !!! (inits ... (var init)) (updates ... (var update))
(more ...) until body ...)]
[(do* !!! (inits ...) (updates ...)
((var init) more ...) until body ...)
(do* !!! (inits ... (var init)) (updates ... )
(more ...) until body ...)]
[(do* !!! inits updates () until body ...)
(do*-aux inits updates until body ...)]
[(do* inits-updates until stuff ...)
(do* !!! () () inits-updates until stuff ...)]))

(do* ((x 0 (+ 1 x))
(y 922))
((= 9 x) (print 'ok))
(print x " " y))

0 922
1 922
2 922
3 922
4 922
5 922
6 922
7 922
8 922
ok

B. Pym

2024-08-30 01:15:59 UTC

Permalink

Post by B. Pym

(defun my-test ()
(loop for number = (1+ (random 6))
as sum = number then (+ sum number)
until (= number 1)
do (format t "~&~D thrown. Sum: ~D" number sum)
finally (format t "~&One thrown.")))

Gauche Scheme
(use srfi-1) ;; unfold
(use srfi-27) ;; random-integer
(define (my-test)
(fold
(^(n sum) (print n " thrown. Sum: " (inc! sum n)) sum)
0
(cdr (unfold zero? ($ + 1 $) (^_ (random-integer 6)) -1)))
(print "One thrown."))
gosh> (my-test)
2 thrown. Sum: 2
2 thrown. Sum: 4
6 thrown. Sum: 10
One thrown.
gosh> (my-test)
One thrown.
Function: unfold end-test key gen-next-seed seed :optional tail-gen
(unfold zero? (lambda(n) (+ 800 n)) (lambda(n) (- n 1)) 7)
===>
(807 806 805 804 803 802 801)
(unfold zero? (lambda(n) (+ 800 n)) (lambda(n) (- n 1)) 7
(lambda(n) (list "The number" n "ended the unfolding.")))
===>
(807 806 805 804 803 802 801 "The number" 0 "ended the unfolding.")

Using "do" is a bit tricky, but the result is shorter.
(define (my-test)
(do ((n #f (+ 1 (random-integer 6)))
(sum 0))
((eqv? 1 n) (print "One thrown."))
(if n (print n " thrown. Sum: " (inc! sum n)))))

It seems to me that "do*" is more appropriate for this,
but this version is 2 characters longer!
(define (my-test)
(do* ((n #f (+ 1 (random-integer 6)))
(sum 0 (+ n sum)))
((eqv? 1 n) (print "One thrown."))
(if n (print n " thrown. Sum: " sum))))
I don't know why Common Lisp has "do*", but Gauche, Racket,
and Chicken Scheme don't.
Here's a version that I cobbled together. (A macro guru
may give us a better one.) "do" is to "do*" as "let" is
to "let*".
(define-syntax do*-aux
(syntax-rules ()
[(do* (inits ...) ((var update) ...) (test expr ...) stuff ...)
(let* (inits ...)
(if test
(begin expr ...)
(begin
(begin stuff ...)
(let loop ()
(begin (set! var update) ...)
(if test
(begin expr ...)
(begin stuff ...
(loop)))))))]))
(define-syntax do*
(syntax-rules (!!!)
[(do* !!! (inits ...) (updates ...)
((var init update) more ...) until body ...)
(do* !!! (inits ... (var init)) (updates ... (var update))
(more ...) until body ...)]
[(do* !!! (inits ...) (updates ...)
((var init) more ...) until body ...)
(do* !!! (inits ... (var init)) (updates ... )
(more ...) until body ...)]
[(do* !!! inits updates () until body ...)
(do*-aux inits updates until body ...)]
[(do* inits-updates until stuff ...)
(do* !!! () () inits-updates until stuff ...)]))
(do* ((x 0 (+ 1 x))
(y 922))
((= 9 x) (print 'ok))
(print x " " y))
0 922
1 922
2 922
3 922
4 922
5 922
6 922
7 922
8 922
ok

Another way:

(define (my-test)
(let1 r (cut + 1 (random-integer 6))
(do* ((n (r) (r))
(sum n (+ n sum)))
((eqv? 1 n) (print "One thrown."))
(print n " thrown. Sum: " sum))))

B. Pym

2024-08-30 05:51:09 UTC

Permalink

Post by B. Pym

(defun my-test ()
(loop for number = (1+ (random 6))
as sum = number then (+ sum number)
until (= number 1)
do (format t "~&~D thrown. Sum: ~D" number sum)
finally (format t "~&One thrown.")))

Gauche Scheme
(use srfi-1) ;; unfold
(use srfi-27) ;; random-integer
(define (my-test)
(fold
(^(n sum) (print n " thrown. Sum: " (inc! sum n)) sum)
0
(cdr (unfold zero? ($ + 1 $) (^_ (random-integer 6)) -1)))
(print "One thrown."))
gosh> (my-test)
2 thrown. Sum: 2
2 thrown. Sum: 4
6 thrown. Sum: 10
One thrown.
gosh> (my-test)
One thrown.
Function: unfold end-test key gen-next-seed seed :optional tail-gen
(unfold zero? (lambda(n) (+ 800 n)) (lambda(n) (- n 1)) 7)
===>
(807 806 805 804 803 802 801)
(unfold zero? (lambda(n) (+ 800 n)) (lambda(n) (- n 1)) 7
(lambda(n) (list "The number" n "ended the unfolding.")))
===>
(807 806 805 804 803 802 801 "The number" 0 "ended the unfolding.")

Using "do" is a bit tricky, but the result is shorter.
(define (my-test)
(do ((n #f (+ 1 (random-integer 6)))
(sum 0))
((eqv? 1 n) (print "One thrown."))
(if n (print n " thrown. Sum: " (inc! sum n)))))

It seems to me that "do*" is more appropriate for this,
but this version is 2 characters longer!
(define (my-test)
(do* ((n #f (+ 1 (random-integer 6)))
(sum 0 (+ n sum)))
((eqv? 1 n) (print "One thrown."))
(if n (print n " thrown. Sum: " sum))))
I don't know why Common Lisp has "do*", but Gauche, Racket,
and Chicken Scheme don't.
Here's a version that I cobbled together. (A macro guru
may give us a better one.) "do" is to "do*" as "let" is
to "let*".
(define-syntax do*-aux
(syntax-rules ()
[(do* (inits ...) ((var update) ...) (test expr ...) stuff ...)
(let* (inits ...)
(if test
(begin expr ...)
(begin
(begin stuff ...)
(let loop ()
(begin (set! var update) ...)
(if test
(begin expr ...)
(begin stuff ...
(loop)))))))]))
(define-syntax do*
(syntax-rules (!!!)
[(do* !!! (inits ...) (updates ...)
((var init update) more ...) until body ...)
(do* !!! (inits ... (var init)) (updates ... (var update))
(more ...) until body ...)]
[(do* !!! (inits ...) (updates ...)
((var init) more ...) until body ...)
(do* !!! (inits ... (var init)) (updates ... )
(more ...) until body ...)]
[(do* !!! inits updates () until body ...)
(do*-aux inits updates until body ...)]
[(do* inits-updates until stuff ...)
(do* !!! () () inits-updates until stuff ...)]))
(do* ((x 0 (+ 1 x))
(y 922))
((= 9 x) (print 'ok))
(print x " " y))
0 922
1 922
2 922
3 922
4 922
5 922
6 922
7 922
8 922
ok

(define (my-test)
(let1 r (cut + 1 (random-integer 6))
(do* ((n (r) (r))
(sum n (+ n sum)))
((eqv? 1 n) (print "One thrown."))
(print n " thrown. Sum: " sum))))

Use ":for" when the same expression is to be assigned
to the variable every time.

(define-syntax do@-aux
(syntax-rules ()
[(do* (inits ...) ((var update) ...) (test expr ...) stuff ...)
(let* (inits ...)
(if test
(begin expr ...)
(begin
(begin stuff ...)
(let loop ()
(begin (set! var update) ...)
(if test
(begin expr ...)
(begin stuff ...
(loop)))))))]))

(define-syntax do@
(syntax-rules (:for !!!)
[(do@ !!! (inits ...) (updates ...)
((:for var expr) more ...) until body ...)
(do@ !!! (inits ... (var expr)) (updates ... (var expr))
(more ...) until body ...)]
[(do@ !!! (inits ...) (updates ...)
((var init update) more ...) until body ...)
(do@ !!! (inits ... (var init)) (updates ... (var update))
(more ...) until body ...)]
[(do@ !!! (inits ...) (updates ...)
((var init) more ...) until body ...)
(do@ !!! (inits ... (var init)) (updates ... )
(more ...) until body ...)]
[(do@ !!! inits updates () until body ...)
(do@-aux inits updates until body ...)]
[(do@ inits-updates until stuff ...)
(do@ !!! () () inits-updates until stuff ...)]))

(define (my-test)
(do@ ((:for n (+ 1 (random-integer 6)))
(sum n (+ n sum)))
((= 1 n) (print "One thrown."))
(print n " thrown. Sum: " sum)))