Re: [racket-users] db: postgresql current_date -> timestamptz
On 7/20/2015 6:08 PM, Jay Kominek wrote: You might be ending up with different timezones set on the different connections, as libpq clients can automatically set/change some session settings that the racket library does not. I'd try running "show timezone" via both connections, and see what you end up with. Hi Jay, I think you hit the nail on the head. Somewhere I am setting the timestamp in UTC and somehow reading it back in local time. I think I was confused because the PG docs say *current_date* always produces time = 00:00:00 when coerced to a timestamp ... but I glossed over that the docs were using timestamp _without_ time zone. After a bit of experimenting, it appears that if a date is coerced to 'timestamp with time zone', the hour is adjusted so the time only reads 00:00:00 if you write and read back using the same time zone setting. I am using a connection pool, but I /thought/ I was executing /*set session time zone 0*/ (for UTC) on every connection before using it. Thanks for pointing me in the right direction. George -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[racket-users] Macro to extract select subexpressions into other locations
I'm trying to create a way to automatically turn test cases into examples. I'd
like a macro that turns this:
(extract-expressions
(module+ test
(check-equal? (extract-expression (square 5)) 25)
(check-equal? (extract-expression (square -5)) 25))
(module+ doc
@defproc[(square [x real?]) real?]{
Returns the square of @racket[x], the result of
multiplying @racket[x] by itself.
@examples[#:eval evaluator (include-extracted-expressions)]}))
into this:
(begin
(module+ test
(check-equal? (square 5) 25))
(module+ doc
@defproc[(square [x real?]) real?]{
Returns the square of @racket[x], the result of
multiplying @racket[x] by itself.
@examples[#:eval evaluator (square 5) (square -5)]}))
That's the general idea anyway. I want to be able to gather arbitrary
expressions inside a region and "copy" them into some other marked place inside
the expressions. How exactly do I go about doing this, and how should I do it
"properly"?
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Re: [racket-users] db: postgresql current_date -> timestamptz
You might be ending up with different timezones set on the different
connections, as libpq clients can automatically set/change some
session settings that the racket library does not. I'd try running
"show timezone" via both connections, and see what you end up with.
On Mon, Jul 20, 2015 at 12:29 PM, George Neuner wrote:
> Hi all,
>
> I'm found something strange with Racket 6.1.1 and Postgresql (9.3.6): SQL
> that works differently in a Racket query than in the DB console.
>
>
> I have a table defined as
>
>create table blah
>(
> a char(15),
> b char(15),
> created timestamp with time zone,
> expires timestamp with time zone
>);
>
> and an insert query
>
>(set! sql-cmd (string-join `(
> "insert into blah (a,b,created,expires)"
> " values ( $1"
> " ,$2"
> " ,current_date"
> " ,current_date + interval '" ,(number->string
> (expire-days)) " days'"
> " )"
> )))
>(query-exec db sql-cmd "some_characters" "more_characters" )
>
> where the value of (expire-days) is 30.
>
>
> When I execute this in Racket, the dates entered into the table are off by 1
> day and have an erroneous hour component: e.g., today is 7-20, the values
> entered are created = 2015-07-19 20:00:00-04 and expires = 2015-08-18
> 20:00:00-04.
>
> Obviously the problem is with current_date, however ...
>
>
> When I execute the analogous code directly from the DB console
>
>insert into stats.surveys_restrict (a,b,created,expires)
> values ('some_characters'
> ,'more_characters'
> ,current_date
> ,current_date + interval '30 days')
>
> I get the expected values: created = 2015-07-20 00:00:00-04 and expires =
> 2015-08-19 00:00:00-04.
>
>
> Since the dates are in the SQL code rather than passed arguments to the
> Racket query call, I don't understand how this is happening ... I would have
> expected to see the same behavior in the console. Casting the dates to type
> timestamptz in the SQL doesn't change the results (in either Racket or the
> console).
>
> If I substitute current_timestamp instead of current_date, the query works
> as expected both in Racket and in the console. However, the Postgresql docs
> say that current_date is coerced to timestamp and the behavior of the
> console seems to confirm that. I don't understand why I get a different
> value from the Racket query.
>
> This isn't a I problem per se as I can substitute current_timestamp without
> issue, but since the program logic currently doesn't need the time
> component, I had thought to use current_date instead.
>
> Any clues as to what is happening?
> George
>
>
> --
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> "Racket Users" group.
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> email to racket-users+unsubscr...@googlegroups.com.
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--
Jay Kominek
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Re: [racket-users] 6.2 regression in running tests?
Sorry for the delay. It has been a very interesting week in the low level implementation of Racket. A few days ago, Matthew fixed the bug and enabled the new expander, and then he fixed most of the problems that appear with the changes. So now looks like a good time to retry all the tests and see if the test are working with the snapshot version of Racket. Following this idea, I remembered that the rackjure project ( https://github.com/greghendershott/rackjure ) has a .travis.yml file, to get continuous integration tests in Travis. It uses a trick to run the project with the latest 10 versions of Racket. You can configure it to run less versions, for example only 6.0.1, 6.1.1 and HEAD (but allow errors in HEAD). You should look at the file in the repository because it's very clear, and if you have a problem you may ask the author because he usually reads the list. This will give you a report of the errors that the next version of Racket would create, and you can send an early warning to the list. This will be helpfull to fix the errors before shipping. Gustavo On Wed, Jul 15, 2015 at 4:14 AM, Ryan Davis wrote: > >> On Jul 14, 2015, at 20:19, Gustavo Massaccesi wrote: >> >> Replacing the line 1758 of optimize.c >> >> - if ((info->inline_fuel < 0) && info->has_nonleaf && !noapp) >> + if ((info->inline_fuel <= 0) && info->has_nonleaf && !noapp) >> >> make the problem disappear, but I still don't understand why "(dup >> rep)" is the only combination that creates a problem. >> >> I also want to think about the "(info->inline_fuel >= 0)" in line 1872 >> and how that interacts with the "if (noapp)" in line 1876 ... > > Thanks! I can test against my whole suite in tomorrow's daily if you'd like. > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [racket-users] Macro introduce identifiers in the new expander
Repair pushed. > On Jul 20, 2015, at 11:14 AM, Matthew Flatt wrote: > > Thanks for the info. I think it's a bug in the expander, and I have a > repair, but I think that repair might point to another bug that I'm > still investigating. > > At Mon, 20 Jul 2015 12:56:49 -0400, "Alexander D. Knauth" wrote: >> I don't really know what's going on, but this might help: >> >> ;; It seems to be introducing the definition correctly, but not the use: >> ;; this works >> (let () >> (def) ; no difference between (def) and (define id 5) >> id) >> >> ;; this doesn't >> (let () >> (def) >> (use)) ; but there is a difference between (use) and id >> >> ;; and this doesn't either >> (let () >> (define id 5) >> (use)) >> >>> On Jul 20, 2015, at 12:35 PM, Spencer Florence wrote: >>> >>> Hello, >>> >>> I'm trying to update some code to the new expander. The below code works on >> 6.2 but fails on the new expander with an unbound identifier error. >>> >>> #lang racket >>> (require (for-syntax syntax/parse)) >>> >>> ;; a standard context for identifiers >>> (define-for-syntax ctx #'ctx) >>> >>> ;; create an ID with the context `ctx`, and the current >>> ;; expander mark (so that the mark is canceled later), >>> ;; and the location loc >>> (define-for-syntax (make-id loc) >>> (syntax-local-introduce >>> (datum->syntax ctx 'id loc))) >>> >>> ;; This introduces a binding >>> (define-syntax (def stx) >>> (syntax-parse stx >>>[(def) >>> (with-syntax ([id (make-id #'here)]) >>> #'(define id 5))])) >>> >>> ;; this attempts to use the binding introduced by `def` >>> (define-syntax (use stx) >>> (syntax-parse stx >>>[(use) >>> (with-syntax ([id (make-id #'here)]) >>> #'id)])) >>> >>> ;; this works >>> #; >>> (begin >>> (def) >>> (use)) >>> >>> ;; this fails >>> (let () >>> (def) >>> (use)) >>> >>> -- >>> You received this message because you are subscribed to the Google Groups >> "Racket Users" group. >>> To unsubscribe from this group and stop receiving emails from it, send an >> email to racket-users+unsubscr...@googlegroups.com. >>> For more options, visit https://groups.google.com/d/optout. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Racket Users" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to racket-users+unsubscr...@googlegroups.com. >> For more options, visit https://groups.google.com/d/optout. > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[racket-users] db: postgresql current_date -> timestamptz
Hi all,
I'm found something strange with Racket 6.1.1 and Postgresql (9.3.6):
SQL that works differently in a Racket query than in the DB console.
I have a table defined as
create table blah
(
a char(15),
b char(15),
created timestamp with time zone,
expires timestamp with time zone
);
and an insert query
(set! sql-cmd (string-join `(
"insert into blah (a,b,created,expires)"
" values ( $1"
" ,$2"
" ,current_date"
" ,current_date + interval '" ,(number->string
(expire-days)) " days'"
" )"
)))
(query-exec db sql-cmd "some_characters" "more_characters" )
where the value of (expire-days) is 30.
When I execute this in Racket, the dates entered into the table are off
by 1 day and have an erroneous hour component: e.g., today is 7-20, the
values entered are created = 2015-07-19 20:00:00-04 and expires =
2015-08-18 20:00:00-04.
Obviously the problem is with current_date, however ...
When I execute the analogous code directly from the DB console
insert into stats.surveys_restrict (a,b,created,expires)
values ('some_characters'
,'more_characters'
,current_date
,current_date + interval '30 days')
I get the expected values: created = 2015-07-20 00:00:00-04 and
expires = 2015-08-19 00:00:00-04.
Since the dates are in the SQL code rather than passed arguments to the
Racket query call, I don't understand how this is happening ... I would
have expected to see the same behavior in the console. Casting the dates
to type timestamptz in the SQL doesn't change the results (in either
Racket or the console).
If I substitute current_timestamp instead of current_date, the query
works as expected both in Racket and in the console. However, the
Postgresql docs say that current_date is coerced to timestamp and the
behavior of the console seems to confirm that. I don't understand why I
get a different value from the Racket query.
This isn't a I problem per se as I can substitute current_timestamp
without issue, but since the program logic currently doesn't need the
time component, I had thought to use current_date instead.
Any clues as to what is happening?
George
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Re: [racket-users] Macro introduce identifiers in the new expander
Thanks for the info. I think it's a bug in the expander, and I have a repair, but I think that repair might point to another bug that I'm still investigating. At Mon, 20 Jul 2015 12:56:49 -0400, "Alexander D. Knauth" wrote: > I don't really know what's going on, but this might help: > > ;; It seems to be introducing the definition correctly, but not the use: > ;; this works > (let () > (def) ; no difference between (def) and (define id 5) > id) > > ;; this doesn't > (let () > (def) > (use)) ; but there is a difference between (use) and id > > ;; and this doesn't either > (let () > (define id 5) > (use)) > > On Jul 20, 2015, at 12:35 PM, Spencer Florence wrote: > > > Hello, > > > > I'm trying to update some code to the new expander. The below code works on > 6.2 but fails on the new expander with an unbound identifier error. > > > > #lang racket > > (require (for-syntax syntax/parse)) > > > > ;; a standard context for identifiers > > (define-for-syntax ctx #'ctx) > > > > ;; create an ID with the context `ctx`, and the current > > ;; expander mark (so that the mark is canceled later), > > ;; and the location loc > > (define-for-syntax (make-id loc) > > (syntax-local-introduce > >(datum->syntax ctx 'id loc))) > > > > ;; This introduces a binding > > (define-syntax (def stx) > > (syntax-parse stx > > [(def) > > (with-syntax ([id (make-id #'here)]) > >#'(define id 5))])) > > > > ;; this attempts to use the binding introduced by `def` > > (define-syntax (use stx) > > (syntax-parse stx > > [(use) > > (with-syntax ([id (make-id #'here)]) > >#'id)])) > > > > ;; this works > > #; > > (begin > > (def) > > (use)) > > > > ;; this fails > > (let () > > (def) > > (use)) > > > > -- > > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > > For more options, visit https://groups.google.com/d/optout. > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [racket-users] Macro introduce identifiers in the new expander
I don't really know what's going on, but this might help: ;; It seems to be introducing the definition correctly, but not the use: ;; this works (let () (def) ; no difference between (def) and (define id 5) id) ;; this doesn't (let () (def) (use)) ; but there is a difference between (use) and id ;; and this doesn't either (let () (define id 5) (use)) On Jul 20, 2015, at 12:35 PM, Spencer Florence wrote: > Hello, > > I'm trying to update some code to the new expander. The below code works on > 6.2 but fails on the new expander with an unbound identifier error. > > #lang racket > (require (for-syntax syntax/parse)) > > ;; a standard context for identifiers > (define-for-syntax ctx #'ctx) > > ;; create an ID with the context `ctx`, and the current > ;; expander mark (so that the mark is canceled later), > ;; and the location loc > (define-for-syntax (make-id loc) > (syntax-local-introduce >(datum->syntax ctx 'id loc))) > > ;; This introduces a binding > (define-syntax (def stx) > (syntax-parse stx > [(def) > (with-syntax ([id (make-id #'here)]) >#'(define id 5))])) > > ;; this attempts to use the binding introduced by `def` > (define-syntax (use stx) > (syntax-parse stx > [(use) > (with-syntax ([id (make-id #'here)]) >#'id)])) > > ;; this works > #; > (begin > (def) > (use)) > > ;; this fails > (let () > (def) > (use)) > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[racket-users] Macro introduce identifiers in the new expander
Hello, I'm trying to update some code to the new expander. The below code works on 6.2 but fails on the new expander with an unbound identifier error. #lang racket (require (for-syntax syntax/parse)) ;; a standard context for identifiers (define-for-syntax ctx #'ctx) ;; create an ID with the context `ctx`, and the current ;; expander mark (so that the mark is canceled later), ;; and the location loc (define-for-syntax (make-id loc) (syntax-local-introduce (datum->syntax ctx 'id loc))) ;; This introduces a binding (define-syntax (def stx) (syntax-parse stx [(def) (with-syntax ([id (make-id #'here)]) #'(define id 5))])) ;; this attempts to use the binding introduced by `def` (define-syntax (use stx) (syntax-parse stx [(use) (with-syntax ([id (make-id #'here)]) #'id)])) ;; this works #; (begin (def) (use)) ;; this fails (let () (def) (use)) -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [racket-users] using `module*` with the new macro expander
> The new expander treats submodules like everything else. Since > `racket/math`, is macro-introduced while the body of the submodule `pi` > is not, the import doesn't bind `pi`. For that matter, the initial > `racket/base` import is also macro-introduced and doesn't bind `#%top` > for `pi`. OK, this is the part I was missing: the old expander did a little magic with certain identifiers within submodules, but no longer. > To make this example work with the new expander, one solution is to use > `syntax/strip-context` to make a macro that behaves like > `module*-macro` with the old expander, but with context stripping by > the macro instead of by `module*`: As an alternative, is it acceptable / wise to continue use `with-syntax` to introduce the identifiers that the new expander omits? E.g., this also will fix the macro: (define-syntax (module*-macro stx) (syntax-case stx () [(_ exprs ...) (with-syntax ([racket/base (format-id stx "~a" #'racket/base)]) #'(module* submod-name racket/base exprs ...))])) > I think it's relatively common for macros that introduce submodules to > intend non-hygienic binding for the macro body --- so, this is a > significant incompatibility. I didn't see a way to keep the old > behavior, though, without defeating some advantages of the new > expander. It sounds like the new expander doesn't forbid this kind of macrology, but rather requires the author to be more explicit about it. -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [racket-users] Current snapshot: problem with generic interfaces and contracts
That was a bug in the revised implementation of `define-generics` for the new expander. I've pushed a repair. At Sun, 19 Jul 2015 22:34:36 -0400, "Alexander D. Knauth" wrote: > This is a simplified example of something that worked in racket version > 6.2.0.4 from 2015-06-08, but is now broken in version 6.2.900.4 from > 2015-07-17. > > gen-foo.rkt: > #lang racket > (provide gen:foo foo? foo/c (contract-out [bar (foo? . -> . any/c)])) > (require racket/generic) > (define-generics foo > (bar foo)) > > contract.rkt: > #lang racket > (require "gen-foo.rkt") > (define (foo/c* c) > (foo/c >[bar (foo? . -> . c)])) > > This works fine in the snapshot from last month, but in the current one, it > fail with this error: > . redirect-generics: bar is not a method of generic interface gen:foo in: bar > > One way to get around this is to export an uncontracted version from > gen-foo.rkt, and possibly put the `bar` contract in a separate, third module, > but why would this be broken now? > > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [racket-users] using `module*` with the new macro expander
At Sun, 19 Jul 2015 22:31:32 -0700, Matthew Butterick wrote: > This code works fine in the stable releases, but the new macro > expander breaks it. I've scrutinized the updated docs for `module*` > but I'm not clear why this would be so. Sorry, this is one of those cases where I haven't yet pushed transition information into the docs. For now, the change is described in the first bullet of section 4.2 in notes on the new expander: http://www.cs.utah.edu/~mflatt/scope-sets-5/implementation.html#%28part._compat%29 > #lang racket/base > > ;; non-macro version works fine > (module* submod-name0 racket/base > 42) > > (define-syntax-rule (module*-macro exprs) > (module* submod-name racket/base > exprs)) > > ;; macro version throws error > (module*-macro 42) To make this example work with the new expander, one solution is to use `syntax/strip-context` to make a macro that behaves like `module*-macro` with the old expander, but with context stripping by the macro instead of by `module*`: #lang racket/base (require (for-syntax racket/base syntax/strip-context)) (define-syntax (module*-macro stx) (syntax-case stx () [(_ exprs) #`(module* submod-name racket/base #,(strip-context #'exprs))])) ;; macro version throws error (module*-macro 42) Meanwhile, I can explain more why this change happened. Let's start with a different example: #lang racket/base (define-syntax-rule (def-one-and-then... e) (begin (define one 1) e)) (def-one-and-then... one) ; unbound `one` In both the old and new expanders, the final `one` doesn't reference the definition introduced by `def-one-and-then...`, because the defined `one` is macro-introduced. It's the same with imports in both expanders: #lang racket/base (define-syntax-rule (req-pi-and-then... e) (begin (require racket/math) e)) (req-pi-and-then... pi) ; unbound `pi` The macro-introduced `(require racket/math)` doesn't bind `pi`. In the old expander, submodules were treated differently, and `pi` below would refer to the binding from `racket/math`. #lang racket/base (define-syntax-rule (req-pi-and-then... e) (module s racket/base (require racket/math) e)) (req-pi-and-then... pi) The new expander treats submodules like everything else. Since `racket/math`, is macro-introduced while the body of the submodule `pi` is not, the import doesn't bind `pi`. For that matter, the initial `racket/base` import is also macro-introduced and doesn't bind `#%top` for `pi`. In your example, the same thing happens with `module*-macro`: The macro-introduced `racket/base` doesn't bind `#%datum` for `42`. I think it's relatively common for macros that introduce submodules to intend non-hygienic binding for the macro body --- so, this is a significant incompatibility. I didn't see a way to keep the old behavior, though, without defeating some advantages of the new expander. -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [racket-users] Re: How to draw a 3D ball?
The images/icons library contains some tools for generating shaded shapes which may be of use to you. It's what I used to generate my personal icon. http://docs.racket-lang.org/images/Icons.html?q=images On Mon, Jul 20, 2015 at 12:03 PM, Mianlai Zhou wrote: > Hi, > > Thanks for your answer. I meant the former, i.e., a 2D pict of a ball with > some shading to make it look 3D. > Is there any quick way to do it or I have to implement the algorithm by > myself? > > Thanks again. > > > On Mon, Jul 20, 2015 at 8:38 AM, Jack Firth wrote: > >> On Saturday, July 18, 2015 at 7:30:42 PM UTC-7, Mianlai Zhou wrote: >> > Hi all, >> > >> > >> > I am wondering how to change the following code of a 2D circle into a >> 3D ball: >> > >> > >> > (require slideshow) >> > (colorize (filled-ellipse (* size 15) (* size 15)) "red") >> > >> > >> > >> > My intention is to make the picture look like a real ball in >> 3-dimension. Is there such >> > a function existing already in Racket? >> > >> > >> > Thank you in advance. >> >> By "3D ball" do you want a 2D pict of a ball with some shading to make it >> look 3D, or a 3D model of a ball? If it's the latter you can use the pict3d >> package (raco pkg install pict3d): >> >> >> (require pict3d) >> (sphere origin 1) >> >> If you do this in DrRacket, the repl will show a window with a 3D ball >> model in it. You can click it and use the arrow keys to change the angle >> and position you view the ball from. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Racket Users" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to racket-users+unsubscr...@googlegroups.com. >> For more options, visit https://groups.google.com/d/optout. >> > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [racket-users] Re: How to draw a 3D ball?
Hi, Thanks for your answer. I meant the former, i.e., a 2D pict of a ball with some shading to make it look 3D. Is there any quick way to do it or I have to implement the algorithm by myself? Thanks again. On Mon, Jul 20, 2015 at 8:38 AM, Jack Firth wrote: > On Saturday, July 18, 2015 at 7:30:42 PM UTC-7, Mianlai Zhou wrote: > > Hi all, > > > > > > I am wondering how to change the following code of a 2D circle into a 3D > ball: > > > > > > (require slideshow) > > (colorize (filled-ellipse (* size 15) (* size 15)) "red") > > > > > > > > My intention is to make the picture look like a real ball in > 3-dimension. Is there such > > a function existing already in Racket? > > > > > > Thank you in advance. > > By "3D ball" do you want a 2D pict of a ball with some shading to make it > look 3D, or a 3D model of a ball? If it's the latter you can use the pict3d > package (raco pkg install pict3d): > > > (require pict3d) > (sphere origin 1) > > If you do this in DrRacket, the repl will show a window with a 3D ball > model in it. You can click it and use the arrow keys to change the angle > and position you view the ball from. > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[racket-users] saving a BMP in racket
Hi, not sure if this is considered a bug? (send model save-file "model1.bmp" 'bmp) save-file in bitmap%: kind saving not yet implemented: 'bmp I found this link, and it's been 2 years since. Is it an update that will take a long time? http://stackoverflow.com/questions/14987784/how-can-i-save-a-bmp-in-racket -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
