gmane.comp.lang.racket.devel

tcp_listen error handling

Alex Moiseenko — 2013-05-21T01:57:25

Hi. I've successfully started Racket 5.3.4.7 with Geiser server through JNI + SDL2 on Android (and this combination mostly works with small hacks), but got some issues due to racket's implementation. This is last one I'm trying to understand. What should be here instead of the "address" expression?

2349    } else {
2350      scheme_raise_exn(MZEXN_FAIL_NETWORK,
2351                       "tcp-listen: host not found\n"
2352                       " address: %s\n"
2353                       " system error: %N",
2354                       address, 1, err);
2355      return NULL;
2356    }
2357  }
https://github.com/plt/racket/blob/master/src/racket/src/network.c#L2354

It looks like there should be (but i'm not sure)

   address ? address : "#f" // as i see at another place, because it's possible to have NULL according to the:

https://github.com/plt/racket/blob/master/src/racket/src/network.c#L2147

Without such change I got segfault because sch_vsprintf tried to process NULL pointer, when i forgot to grant in

proposal for moving to packages

Matthew Flatt — 2013-05-20T20:42:15

I used to think that we'd take advantage of the package manager by
gradually pulling parts out of the Racket git repo and making them
packages.

Now, I think we should just shift directly to a small-ish Racket core,
making everything else a package immediately. "Core" means enough to
run `raco pkg'.

A key point to remember is that "package" does not mean "omitted from
the distribution". Instead, we'll construct a distribution by
combining the core with a selected set of packages. Initially the
selected set of packages will cover everything in the current
distribution.

Jay and I have been lining up the pieces for this change (it's
difficult to make a meaningful proposal without trying a lot of the
work, first), and I provide a sketch of the overall plan below.

This plan has two prominent implications:

 * The current git repo's directory structure will change.

   Anyone who currently works with the Racket repo will need to adapt
   to the new directory structure (and probably git <submodules in the
   fut

set!-transformers and syntax-local-value/immediate

Asumu Takikawa — 2013-05-17T23:30:35

Hi all,

I'm confused about an aspect of set! and rename transformers. I'll
explain with this example:

  #lang racket

  ;; a macro that uses `syntax-local-value/immediate`
  (define-syntax (lookup stx)
    (syntax-case stx ()
      [(_ id)
       (let-values ([(f _) (syntax-local-value/immediate #'id)])
         (displayln (rename-transformer? f))
         (displayln (set!-transformer? f))
         #'0)]))

  ;; f is a set!-transformer
  (let-syntax ([f (make-set!-transformer values)])
    (lookup f))

  ;; sanity check
  (rename-transformer? (make-set!-transformer values))

In this example, `f` is bound to a set!-transformer. The macro `lookup`
will look up the value bound to `f` at compile-time, and I expected that
the result would be the set! transformer.

However, it seems like the set! transformer is somehow being turned into
a rename transformer (note the two print statements produce #t and #f
respectively). The last line suggests that set! transformers are not
actually a "subtype" of rename transfor

calling make-keyword-procedure from inside a thread produces a stack overflow in scheme_uncopy_stack

Matthew Eric Bassett — 2013-05-15T12:40:04

This is related to 
http://www.mail-archive.com/users-GvBox1K3Ixw1Q5oZIJT9Xw< at >public.gmane.org/msg17597.html. Forgive 
me for posting it again, I wanted to make sure it didn't disappear into 
a black hole.

Launching a racket thread that calls make-keyword-procedure may produce 
a seg fault.  For instance,

(let loop () (thread (make-keyword-procedure (lambda (x y) '()))) 
(loop))

Reliably causes a seg fault.  Repeatedly calling

(thread (make-keyword-procedure (lambda (x y) '())))

will eventually (but not consistently) produce a seg fault.  Functions 
defined with make-keyword-procedure, such as const and thunk* suffer the 
same fate (plain ol' thunk is fine).

A coredump of the racket repl from this segfault shows a stack overflow 
in scheme_uncopy_stack, with the Scheme_Jumpup_Buf zeroed out.  Please 
see our gdp session at http://pastebin.com/aBx2FTcK (This is from racket 
compiled without optimization)  or cause your own seg fault with the 
above code.

Perhaps we're being incredibly daft to write code

svn server going mostly read-only

Eli Barzilay — 2013-05-13T01:49:33

JFYI, I've made the svn server be mostly read-only.

Immediate characters

Jon Zeppieri — 2013-05-12T17:38:23

My branch with immediately represented characters is available at:

https://github.com/97jaz/racket/tree/immediate-chars

I'm interested to hear any opinions from the members of this list on
the implementation.

For my own part, I'm ambivalent on the matter of actually
incorporating this work into the official tree. Benchmarks that are
heavy on character manipulation -- and there are few enough of these

bitmap-dc% ignores alpha on set-pixel

Jay McCarthy — 2013-05-11T01:23:35

No matter what the input color's alpha is, set-pixel uses 100%
opacity. Similarly, get-pixel ignores the alpha in the image.

I think we should change this with the patch below, but I wonder if
there is some deeper reason it works this way and it shouldn't change.
Matthew?

Jay

diff --git a/collects/racket/draw/private/bitmap-dc.rkt
b/collects/racket/draw/private/bitmap-dc.rkt
index 08bb51c..5d9e241 100644
--- a/collects/racket/draw/private/bitmap-dc.rkt
+++ b/collects/racket/draw/private/bitmap-dc.rkt
< at >< at > -119,14 +119,18 < at >< at >
       (internal-get-bitmap))

     (define/public (set-pixel x y c)
-      (let ([s (bytes 255 (color-red c) (color-green c) (color-blue c))])
+      (let ([s (bytes (inexact->exact (round (* 255 (color-alpha c))))
+                      (color-red c)
+                      (color-green c)
+                      (color-blue c))])
         (set-argb-pixels x y 1 1 s)))

     (define/public (get-pixel x y c)
       (let-values ([(w h) (get-size)])
         (let ([b (make-bytes 4)])

Another JIT question

Jon Zeppieri — 2013-05-11T01:19:25

My experiment with immediately represented characters has gotten to a
state where a non-JIT build passes all tests, but a JIT build fails
(as in, segfaults) on the following program:

#\c

It also fails on:

(integer->char 99)

and:

(define (foo x) (integer->char x))
(foo 99)

but not on:

(define (foo x) (write (integer->char x)))
(foo 99)

So there seems to be a problem returning a character from a jitted
function back to the repl. I haven't been able to figure out where
this occurs, though. gdb's stack traces don't seem very useful for
jitted code, and I can't use Sam's disassembler, because the process
dies.

Any idea where to look or what debugging tools might be useful?

-Jon
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Keywords

Laurent — 2013-05-09T14:22:54


I've always wondered why the syntax of keywords implied two elements: the
#:keyword and the identifier.
I find that quite heavy for procedure headers, and most of the time I use
the same symbol for the identifier and the keyword (and when I don't it's
because I'm simply lazy and use a shorter identifier).

Is there a rationale somewhere for that?
Would it be a bad idea for Racket2 to consider that keyword identifiers are
the same as the keyword without the `#:' ?

Laurent
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[ANN] RacketCon 2013: 29 September

Asumu Takikawa — 2013-05-08T15:49:49

RacketCon 2013
--------------

We are pleased to announce that (third RacketCon) will take place on
September 29, 2013 at Northeastern University in Boston.  This year, we
plan to bring in several speakers from industry, as well as host talks
from Racket developers and users.

Lunch will be provided.

On the Saturday (28th) before RacketCon, we plan to hold a hackathon to work on
various Racket projects.

Registration will open during the summer, and we will post a detailed
schedule of events around the same time. The conference website is at

  http://con.racket-lang.org/

Asumu Takikawa and PLT

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Package system quickstart section?

Asumu Takikawa — 2013-05-08T12:56:19

Hi all,

Would anyone be opposed to adding a "Quickstart" section to the Package
System documentation page? The current first section[1] is useful, but
it's a pretty dense read for someone who just wants to know how to
install a package.

I'm imagining that the Quickstart would describe where to find packages
(pkg.racket-lang.org, github, etc.) and the commands you need to type to
install a package from typical sources. Maybe screenshots showing how to
use the package GUI.

[1]: http://docs.racket-lang.org/planet2/Package_Concepts.html

Cheers,
Asumu
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JIT question

Jon Zeppieri — 2013-05-07T21:29:52

I realize that I should get a --disable-jit version running before
tackling this, but since I stumbled into it last night...

In jitinline.c, at line 1834, there is code for generating a JIT-ted
version of char->integer. I think I understand all of it, except for
line 1851:

1851: jit_movr_p(dest, JIT_R0);

If the initial test (at line 1846 succeeds, then we jump past this
instruction (although we might jump back later, if the type-tag test
(at 1853) fails (well, succeeds, I suppose). But, if we ever get to
the code at line 1849:

(void)jit_calli(sjc.bad_char_to_integer_code);

Then we're never going to return from there... I think. So, I'm not
sure what execution path the code could take where that move
instruction would matter. Also, assuming that instruction is
reachable, I still don't know what it's for.

Can anyone (probably Matthew) enlighten me?

-Jon
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`configure-runtime' submodule

Matthew Flatt — 2013-05-07T13:17:16

When you run

 #lang racket
 '#(1 1 1)

the output is

 '#(1 1 1)


When you run 

 #lang scheme
 '#(1 1 1)

the output is

 #(1 1 1)


The difference in output (i.e., whether there's a leading quote) is
because the `racket' and `scheme' languages arrange different run-time
configuration of printing parameters. The language of a program's main
module determines the configuration that is used.


Until version 5.3.4.8, this run-time configuration was implemented via
the `#lang' reader, which attached a syntax property to the module,
which was preserved in the bytecode and accessed via
`module->language-info', which produced a vector that referred to
another module and a name of one of its exports, and so on... The
complex chain of indirections was designed to enable loading code for
different times at the right time --- but that's what submodules are
for.

Now, command-line `racket', DrRacket, and `raco exe' look for a
`configure-runtime' submodule of a program's main module to be run
before the main module. T

git.racket-lang.org unhappy

Robby Findler — 2013-05-07T04:06:22

It says "503 - The load average on the server is too high".

Robby
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stypes.h + 3M woes

Jon Zeppieri — 2013-05-06T00:16:46

When I try to make a hole in the enumeration defined in stypes.h (by
explicitly setting the value of a member), I get a segfault in the 3m
build, though not the cgc one.

Depending on where I place the hole, I've seen different stack traces.
If I place the new tag before the _rt_ tags, then I get:

#0  0x00007fff886d9db0 in bzero$VARIANT$sse42 ()
#1  0x000000010030d5ea in malloc_pages () at vm_osx.c:185
#2  0x0000000100314106 in allocate_big (request_size_bytes=32807,
type=0) at newgc.c:974
#3  0x0000000100314e08 in GC_malloc_weak_array (size_in_bytes=16384,
replace_val=0x0) at newgc.c:1463

If I place it after (which is where I want to place it), I get:

#0  0x0000000000000000 in ?? ()
#1  0x0000000100310e9f in repair_heap [inlined] () at
/Users/jaz/src/racket/src/racket/gc2/newgc.c:4171
#2  0x0000000100310e9f in garbage_collect (gc=0x7fff5fbf7c00,
force_full=5339440, switching_master=1606384640, lmi=0x7fff5fbf7c00)
at newgc.c:4753
#3  0x000000010031487a in scheme_get_thread_local_variables [inlined]
() at

Racket2 suggestion: Attaching properties to operators

Laurent — 2013-05-05T15:00:52

Speaking of invariants, from time to time I would like Racket to know some
properties about its usual operators, so that some usual treatments get
simplified and can be easily generalized.

For example, considering group theory, properties like 'identity-element',
'absorbing-elements', 'inverse-operator', 'commutative?', 'associative?'
and such could be attached to operators like `+', `*', `max',
`string-append', `hc-append', etc.
Forms like `for/op' could use this information to know how to loop and
accumulate, and even possibly to optimize the code, even for newly created
operators.
In the simple case of + and such, one also only needs to define the binary
operator, and the multi-argument procedure can be generated automatically.

Of course it needs not be tied to group/category/mathematical theory. It
can be about whatever is useful.

It's only an idea, in case this resonates for someone.

Laurent
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racket2 suggestion: removing (or extending) eqv?

Jon Zeppieri — 2013-05-04T15:57:21

Since incompatible future changes seem to be coming up a lot, I
thought I'd add one more. What do the members of this list think of
removing eqv? all of its associated machinery (e.g., memv, hasheqv,
etc.)?

(Along with this change, it would be nice if characters could all be
immediately represented, so that those with equal code points would be
eq? RIght now, all unicode code points can be encoded in 22 bits, I
think. I'm not so familiar with racket's current representation of
characters, but I figure that they could easily be fit into a single
machine word on 64-bit builds. I don't know how difficult it would be
on 32-bit builds. And, of course, there's no guarantee that the number
of code points won't increase significantly.)

Alternatively (and following Sam's line of thought from [1]), eqv?
could be extended to cover all of racket's immutable data structures.
In this case eqv? should also be made generic so that user-defined
immutable data structures can use it, as well.


[1] http://lists.racket-lang.o

else clauses: possible change to match?

Robby Findler — 2013-05-03T13:39:07

[ for those that just want to see what I'm getting at, scroll to the end ]

While the docs are clear (enough) on this point, I think it can be quite
confusing. See if you spot the bug in this program:

#lang racket
(define (find-literals e)
  (define literals '())
  (let loop ([e e])
    (match e
      [`(λ (,x) ,e)
       (loop e)]
      [`(,e1 ,e2)
       (loop e1)
       (loop e2)]
      [(? symbol?) (void)]
      [else
       (cond
         [(member e literals)
          (void)]
         [else
          (set! literals (cons e literals))])]))
  literals)

(module+ test
  (require rackunit)
  (check-equal? (find-literals '(λ (x) x)) '())
  (check-equal? (find-literals '((λ (x) x) 1)) '(1))
  (check-equal? (find-literals '((λ (x) x) #f)) '(#f)))


Hint: the last test case fails. Second hint: if you switch it to use sets,
it starts working. Third hint: this isn't about lists. :)

































The bug is that 'else' is treated as a variable in match, so it gets bound
to #f, which shadow

Release Announcement for v5.3.4, Final Draft

Ryan Culpepper — 2013-05-01T19:57:45

The release announcement sketch that I have so far is below.  Please
mail me new items and/or edits.
----------------------------------------------------------------------

* Extflonums (80-bit floating-point numbers) are supported on some
   x86/x86_64 platforms --- including Windows, and including
   platforms where Racket is compiled to use SSE instructions for
   flonum arithmetic. Thanks to Michael Filonenko.

* DrRacket (and all of the other apps) are now signed with an
   official OS X key.

* Tally Maze: a new game based an enumeration of 2d mazes.

* The Optimization Coach DrRacket plugin has been moved from the
   Racket distribution to the Racket package repository.

* Redex: define-union-language now merges productions when languages
   define the same nonterminals. Thanks to William Bowman.

* The srfi/19 library is now compatible with the date structure type
   exported by racket/base.

----------------------------------------------------------------------
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  Racket Dev

seeing compile-time error for Whalesong on HEAD

Danny Yoo — 2013-04-29T23:27:29

I'm seeing the following error message on HEAD
(08dc0e10d934cb29b9830a94945c2e38c275a9d8):


application: procedure does not expect an argument with given keyword
  procedure: t->c/both
  given keyword: #:kind
  given arguments:
   Boolean
   #:kind 'impersonator
   #:seen (list (cons
#(struct:#<syntax:/Users/dyoo/work/whalesong/whalesong/promise.rkt:13:20
MyPromise> (Boolean (-> g305) (U Sentinel g305))) #<syntax rec5>))
  context...:
   /Users/dyoo/local/racket/collects/racket/private/kw.rkt:1255:14
   /Users/dyoo/local/racket/collects/typed-racket/private/type-contract.rkt:428:16:
for-loop
   parse-loop178
   /Users/dyoo/local/racket/collects/racket/private/map.rkt:21:13: map
   parse-loop1254
   /Users/dyoo/local/racket/collects/typed-racket/private/type-contract.rkt:215:13
   /Users/dyoo/local/racket/collects/racket/private/map.rkt:21:13: map
   f902
   /Users/dyoo/local/racket/collects/typed-racket/typecheck/provide-handling.rkt:54:2:
mk16
   /Users/dyoo/local/racket/collects/unstable/list.rkt:139:0: m

Pre-Release Checklist for v5.3.4, Second Call

Ryan Culpepper — 2013-04-23T03:29:42

Checklist items for the v5.3.4 release
   (using the v5.3.3.900 release candidate build)

Search for your name to find relevant items, reply when you finish an
item (please indicate which item/s is/are done).  Also, if you have any
commits that should have been picked, make sure that the changes are in.

Important: new builds are created without announcement, usually whenever
I pick a few commits.  If you need to commit changes, please make sure
you tell me to pick it into the release branch.

--> Release candidates are at
-->   http://pre.racket-lang.org/release/installers

Please use these installers (or source bundles) -- don't test from
your own git clone (don't test the `master' branch by mistake!).  To
get the tests directory in such a directory, you can do this:
   cd ...racket-root...
   git archive --remote=git://git.racket-lang.org/plt.git release \
       -- collects/tests | tar x

----------------------------------------------------------------------

* John Clements <clements-USm5ewCNdr/ECKqllll