[Chicken-users] help :)
Hi, I am a newbie to chicken.Can i get some aid as to how to start coding through chicken. I was recently learning racket and also have know-how of Python-2.6. Please guide a little. regards, Nehal Singhal. ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] set! atomic?
From: Bryan Vicknair bryanv...@gmail.com Subject: [Chicken-users] set! atomic? Date: Tue, 4 Jun 2013 19:15:52 -0700 SRFI-18 states: Read and write operations on the store (such as reading and writing a variable, an element of a vector or a string) are not required to be atomic. It is an error for a thread to write a location in the store while some other thread reads or writes that same location. Is it possible to eval a variable that is in an inconsistent state? I understand that if there are a series of set-car! on a list, then a reader may see the list as it is in between any of the set-car! calls. But is it possible that an update to a very large object will ever be interrupted by one thread such that other threads will see a broken version? (use srfi-1) (define foo '(1 2 3)) (thread-start! (make-thread (lambda () (set! foo (iota 1e8) (print foo) In the above code, will the primordial thread ever print a list that isn't exactly (1 2 3) or (iota 1e8)? The assignment itself is fully atomic, as is the destructive modification of any single data-cell like pair-cells, vector-elements or record-structure slots. cheers felix ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] help :)
Hi, Nehal-- Have you seen the Chicken for Python programmers tutorial? http://wiki.call-cc.org/chicken-for-python-programmers That would be a good place to start. Then if you are still unsure how to proceed, you will probably get more help if you ask more specific questions. Best of luck with Chicken! -- Matt Gushee ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] help :)
Hi, On Wed, 5 Jun 2013 16:07:56 +0200 nehal singhal nehalsingha...@gmail.com wrote: I am a newbie to chicken.Can i get some aid as to how to start coding through chicken. I was recently learning racket and also have know-how of Python-2.6. Please guide a little. Welcome. There's the Getting started chapter from the manual: http://wiki.call-cc.org/man/4/Getting%20started Best wishes. Mario -- http://parenteses.org/mario ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
[Chicken-users] Chicken C interface
Hello everybody,
I was planning to use Chicken Scheme in a fashion more similar to Guile and
Lua. i.e. passing Scheme Data Objects from Chicken to C and back using the
C interface.
I am a little confused though as how to have a C function return a Scheme
List that is seen by the garbage collector.
For example, is the code below correct, will the list be seen by the
garbage collector? And if not, is there correct way to do this.
#
C_word give_12()
{
C_word *mem = C_alloc(C_SIZEOF_LIST(2));
C_word list = C_list(mem, 2, C_fix(1), C_fix(2));
return list;
}
#
(print ((foreign-lambda scheme-object give_12)))
Also there doesn't seem to be a C_listp predicate. Is this a concious
omission?
thank you in advance,
Richard
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Re: [Chicken-users] help :)
Feel free to ask questions in the IRC channel, #chicken on irc.freenode.net -Dan On 6/5/2013 7:07 AM, nehal singhal wrote: Hi, I am a newbie to chicken.Can i get some aid as to how to start coding through chicken. I was recently learning racket and also have know-how of Python-2.6. Please guide a little. regards, Nehal Singhal. ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Chicken C interface
I do this a fair bit in the Allegro egg.
Here's an example:
https://github.com/dleslie/allegro-egg/blob/985ca2ceef0f5b4028af3f97729f13cba2976fe5/color.scm
Basically, use C_alloc to allocate the memory required to host both the
List structure and the data it is to contain, then use the C_list macro
to patch it all together.
-Dan
On 6/5/2013 8:10 AM, pluijzer . wrote:
Hello everybody,
I was planning to use Chicken Scheme in a fashion more similar to
Guile and Lua. i.e. passing Scheme Data Objects from Chicken to C and
back using the C interface.
I am a little confused though as how to have a C function return a
Scheme List that is seen by the garbage collector.
For example, is the code below correct, will the list be seen by the
garbage collector? And if not, is there correct way to do this.
#
C_word give_12()
{
C_word *mem = C_alloc(C_SIZEOF_LIST(2));
C_word list = C_list(mem, 2, C_fix(1), C_fix(2));
return list;
}
#
(print ((foreign-lambda scheme-object give_12)))
Also there doesn't seem to be a C_listp predicate. Is this a concious
omission?
thank you in advance,
Richard
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Re: [Chicken-users] help :)
Hey Dan, What's the preferred method to ask? I didn't know about the IRC channel and now I am dubious what would be better if asking over there or using the email list... Cheers, Pedro. On Wed, Jun 5, 2013 at 11:44 AM, Dan Leslie d...@ironoxide.ca wrote: Feel free to ask questions in the IRC channel, #chicken on irc.freenode.net -Dan On 6/5/2013 7:07 AM, nehal singhal wrote: Hi, I am a newbie to chicken.Can i get some aid as to how to start coding through chicken. I was recently learning racket and also have know-how of Python-2.6. Please guide a little. regards, Nehal Singhal. __**_ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/**mailman/listinfo/chicken-usershttps://lists.nongnu.org/mailman/listinfo/chicken-users __**_ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/**mailman/listinfo/chicken-usershttps://lists.nongnu.org/mailman/listinfo/chicken-users -- T: +1 (416) - 357.5356 Skype ID: pmelendezu ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Chicken C interface
On Wed, Jun 05, 2013 at 08:47:45AM -0700, Dan Leslie wrote: I do this a fair bit in the Allegro egg. Here's an example: https://github.com/dleslie/allegro-egg/blob/985ca2ceef0f5b4028af3f97729f13cba2976fe5/color.scm Basically, use C_alloc to allocate the memory required to host both the List structure and the data it is to contain, then use the C_list macro to patch it all together. Also there doesn't seem to be a C_listp predicate. Is this a concious omission? There is no C_listp predicate because you can't directly check an object for being a list; you must check whether it's C_SCHEME_END_OF_LIST (then it is a list). Otherwise, if it's a pair you take its cdr and loop. If it's something else, it's not a list. Because this is a potentially heavy operation (and cyclic lists may even cause an endless loop), I guess it's been decided not to provide a predicate procedure for this, because it's too tricky to get right, and usually you want to avoid traversing the list twice anyway, so the operation itself is often embedded in the CDRing logic. Cheers, Peter -- http://www.more-magic.net ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Chicken C interface
On 2013-06-05 19:50, Peter Bex wrote: [...] There is no C_listp predicate because you can't directly check an object for being a list; you must check whether it's C_SCHEME_END_OF_LIST (then it is a list). Otherwise, if it's a pair you take its cdr and loop. If it's something else, it's not a list. Because this is a potentially heavy operation (and cyclic lists may even cause an endless loop), I guess it's been decided not to provide a predicate procedure for this, [...] Hello, but it's trivial to detect cyclic lists during the traversal using either a set of seen elements or just two iteration pointers travelling at different speeds. The only problematic structures are truly infinite lists without periodicity, but those are impossible with eager data structures like the standard Scheme lists. Ciao, Thomas -- When C++ is your hammer, every problem looks like your thumb. -- When C++ is your hammer, every problem looks like your thumb. ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Chicken C interface
On Wed, Jun 05, 2013 at 07:57:49PM +0200, Thomas Chust wrote: Hello, but it's trivial to detect cyclic lists during the traversal using either a set of seen elements or just two iteration pointers travelling at different speeds. In C that's rather painful. Note that the OP was asking specifically for a C_listp macro. Cheers, Peter -- http://www.more-magic.net ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Chicken C interface
On 2013-06-05 20:11, Peter Bex wrote: On Wed, Jun 05, 2013 at 07:57:49PM +0200, Thomas Chust wrote: but it's trivial to detect cyclic lists during the traversal using either a set of seen elements or just two iteration pointers travelling at different speeds. In C that's rather painful. Note that the OP was asking specifically for a C_listp macro. [...] Hello, well, I think that two iteration pointers are trivial even in C, but that may be a matter of taste :-) Ciao, Thomas -- When C++ is your hammer, every problem looks like your thumb. -- When C++ is your hammer, every problem looks like your thumb. ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Chicken C interface
this should work for basic list test
(import foreign)
#
C_word C_listp(C_word p)
{
if (p == C_SCHEME_END_OF_LIST)
{
return C_SCHEME_TRUE;
}
// check for non-immidiate object and pair?
if (!C_immediatep(p) C_pairp(p) ==
C_SCHEME_TRUE)
{
return
C_listp(C_u_i_cdr(p));
}
return C_SCHEME_FALSE;
}
#
(define listp? (foreign-lambda scheme-object "C_listp" scheme-object))
(print (listp? 1))
(print (listp? (cons 1 2)))
(print (listp? (cons (cons 1 2) (cons 3 4
(print (listp? 1.0))
(print (listp? '(1)))
(print (listp? '(1 2)))
06/05/13 19:10:41, pluijzer . pluij...@gmail.com:
Hello
everybody,
I was planning to use Chicken Scheme in a fashion more similar to
Guile and Lua. i.e. passing Scheme Data Objects from Chicken to C and back
using the C interface.
I am a little confused though as how to have a C function return a
Scheme List that is seen by the garbage collector.
For example, is the code below correct, will the list be seen by the
garbage collector? And if not, is there correct way to do this.
#
C_word give_12()
{
C_word *mem = C_alloc(C_SIZEOF_LIST(2));
C_word list = C_list(mem, 2, C_fix(1), C_fix(2));
return list;
}
#
(print ((foreign-lambda scheme-object "give_12")))
Also there doesn't seem to be a C_listp
predicate. Is this a concious omission?
thank you in advance,
Richard
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Re: [Chicken-users] Chicken C interface
On Wed, Jun 05, 2013 at 08:19:15PM +0200, Thomas Chust wrote: On 2013-06-05 20:11, Peter Bex wrote: On Wed, Jun 05, 2013 at 07:57:49PM +0200, Thomas Chust wrote: but it's trivial to detect cyclic lists during the traversal using either a set of seen elements or just two iteration pointers travelling at different speeds. In C that's rather painful. Note that the OP was asking specifically for a C_listp macro. [...] Hello, well, I think that two iteration pointers are trivial even in C, but that may be a matter of taste :-) Of course you're right. I was thinking of the set of seen elements. I need sleep. Cheers, Peter -- http://www.more-magic.net ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Chicken C interface
From: Dan Leslie d...@ironoxide.ca Subject: Re: [Chicken-users] Chicken C interface Date: Wed, 05 Jun 2013 08:47:45 -0700 I do this a fair bit in the Allegro egg. Here's an example: https://github.com/dleslie/allegro-egg/blob/985ca2ceef0f5b4028af3f97729f13cba2976fe5/color.scm Basically, use C_alloc to allocate the memory required to host both the List structure and the data it is to contain, then use the C_list macro to patch it all together. Note that this code is not correct: C_alloc allocates on the C stack and the data will be invalid once the function returns (Sorry). If this works, then it is just coincidental! cheers, felix ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Chicken C interface
From: pluijzer . pluij...@gmail.com
Subject: [Chicken-users] Chicken C interface
Date: Wed, 5 Jun 2013 17:10:41 +0200
Hello everybody,
I was planning to use Chicken Scheme in a fashion more similar to Guile and
Lua. i.e. passing Scheme Data Objects from Chicken to C and back using the
C interface.
I am a little confused though as how to have a C function return a Scheme
List that is seen by the garbage collector.
For example, is the code below correct, will the list be seen by the
garbage collector? And if not, is there correct way to do this.
#
C_word give_12()
{
C_word *mem = C_alloc(C_SIZEOF_LIST(2));
C_word list = C_list(mem, 2, C_fix(1), C_fix(2));
return list;
}
#
(print ((foreign-lambda scheme-object give_12)))
As written in the other message: C_alloc is just a wrapper around alloca(3),
so returning from the function invalidates or overwrites the data. A later
(minor) garbage collection may actually recover the data, but it is not
certain that it happens. See
http://api.call-cc.org/doc/foreign/access/foreign-primitive
for a variant that allows stack-allocation.
cheers,
felix
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Re: [Chicken-users] Chicken C interface
Oh dear! Well, it works and I haven't had problems. What's the correct way to go about this? -Dan On 6/5/2013 2:36 PM, Felix wrote: From: Dan Leslie d...@ironoxide.ca Subject: Re: [Chicken-users] Chicken C interface Date: Wed, 05 Jun 2013 08:47:45 -0700 I do this a fair bit in the Allegro egg. Here's an example: https://github.com/dleslie/allegro-egg/blob/985ca2ceef0f5b4028af3f97729f13cba2976fe5/color.scm Basically, use C_alloc to allocate the memory required to host both the List structure and the data it is to contain, then use the C_list macro to patch it all together. Note that this code is not correct: C_alloc allocates on the C stack and the data will be invalid once the function returns (Sorry). If this works, then it is just coincidental! cheers, felix ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Chicken C interface
Thanks, I'll get on updating my broken eggs soon.
obvious humpty dumpty joke notwithstanding
-Dan
On 6/5/2013 2:39 PM, Felix wrote:
From: pluijzer . pluij...@gmail.com
Subject: [Chicken-users] Chicken C interface
Date: Wed, 5 Jun 2013 17:10:41 +0200
Hello everybody,
I was planning to use Chicken Scheme in a fashion more similar to Guile and
Lua. i.e. passing Scheme Data Objects from Chicken to C and back using the
C interface.
I am a little confused though as how to have a C function return a Scheme
List that is seen by the garbage collector.
For example, is the code below correct, will the list be seen by the
garbage collector? And if not, is there correct way to do this.
#
C_word give_12()
{
C_word *mem = C_alloc(C_SIZEOF_LIST(2));
C_word list = C_list(mem, 2, C_fix(1), C_fix(2));
return list;
}
#
(print ((foreign-lambda scheme-object give_12)))
As written in the other message: C_alloc is just a wrapper around alloca(3),
so returning from the function invalidates or overwrites the data. A later
(minor) garbage collection may actually recover the data, but it is not
certain that it happens. See
http://api.call-cc.org/doc/foreign/access/foreign-primitive
for a variant that allows stack-allocation.
cheers,
felix
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Re: [Chicken-users] Chicken C interface
I just though I'd mention srfi-4 http://api.call-cc.org/doc/srfi-4 as
well, which are much easier to interface with from C. If all your elements
are integers, for example, you might want to check out u32vector. Srfi-4
vectors use plain C float/int arrays and are possible as argument-types
from foreign-lambda and friends.
K.
On Wed, Jun 5, 2013 at 5:10 PM, pluijzer . pluij...@gmail.com wrote:
Hello everybody,
I was planning to use Chicken Scheme in a fashion more similar to Guile
and Lua. i.e. passing Scheme Data Objects from Chicken to C and back using
the C interface.
I am a little confused though as how to have a C function return a Scheme
List that is seen by the garbage collector.
For example, is the code below correct, will the list be seen by the
garbage collector? And if not, is there correct way to do this.
#
C_word give_12()
{
C_word *mem = C_alloc(C_SIZEOF_LIST(2));
C_word list = C_list(mem, 2, C_fix(1), C_fix(2));
return list;
}
#
(print ((foreign-lambda scheme-object give_12)))
Also there doesn't seem to be a C_listp predicate. Is this a concious
omission?
thank you in advance,
Richard
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Re: [Chicken-users] Chicken C interface
The correct way is to not let C manage memory at all ;-P In the mpi egg, I used foreign-primitive and C_alloc as follows: ;; Returns the current MPI time as a floating-point number (define MPI:wtime (foreign-primitive scheme-object () #EOF C_word result; C_word *ptr; ptr = C_alloc (C_SIZEOF_FLONUM); result = C_number(ptr, MPI_Wtime()); C_return (result); EOF )) In various other C interface libraries, I use the following idiom: (define (func arg) ;; determine the size of the result vector (let* ((n (c_func_result_length arg)) ;; allocate memory for the result vector (v (make-f64vector n 0.0))) ;; obtain result (c_func arg v) v)) This of course assumes that the C library you are targeting is structured so as to allow you to determine the result size. This is often the case with various numerical libraries I have had to interface to, but that's a fairly specific use case. -Ivan On Thu, Jun 6, 2013 at 6:45 AM, Dan Leslie d...@ironoxide.ca wrote: Oh dear! Well, it works and I haven't had problems. What's the correct way to go about this? -Dan On 6/5/2013 2:36 PM, Felix wrote: From: Dan Leslie d...@ironoxide.ca Subject: Re: [Chicken-users] Chicken C interface Date: Wed, 05 Jun 2013 08:47:45 -0700 I do this a fair bit in the Allegro egg. Here's an example: https://github.com/dleslie/**allegro-egg/blob/** 985ca2ceef0f5b4028af3f97729f13**cba2976fe5/color.scmhttps://github.com/dleslie/allegro-egg/blob/985ca2ceef0f5b4028af3f97729f13cba2976fe5/color.scm Basically, use C_alloc to allocate the memory required to host both the List structure and the data it is to contain, then use the C_list macro to patch it all together. Note that this code is not correct: C_alloc allocates on the C stack and the data will be invalid once the function returns (Sorry). If this works, then it is just coincidental! cheers, felix __**_ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/**mailman/listinfo/chicken-usershttps://lists.nongnu.org/mailman/listinfo/chicken-users ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
