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[pro] [Review Request] Small example of modern application of Common Lisp
by Christian von Essen 02 Nov '11

02 Nov '11

Hi, I use CL to scrape several comic websites and generate a website that collects the daily strips from that. The (small) program's features: * Easy definition of comic sources * Uses xpath to get the comics * Stores an archive of daily comics * Generate web pages with comics per day A feature that is IMHO still missing is easier (maybe interactive) comic specification. Currently you better get your xpath right. I think it would be possible to promote CL with an application like that. Could you have a look at the code and give me some hints on style and CL in general, so that the code actually becomes good enough for that purpose? You can find it there: https://github.com/Neronus/Lisp-Utils/blob/master/comics.lisp And an example of the generated output here: http://christian.ftwca.de/comics/ Thank you, Christian

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[pro] Administrativia: Posting through gmame
by Hans Hübner 04 Oct '11

04 Oct '11

Hi, the post earlier today was made through gmame, and that post bounced at multiple subscriber's MTAs because it was considered spam. In order to avoid that, I'm not going to manually forward postings coming in through gmame anymore. Please consider subscribing to the mailing list directly (you can still read through gmame, but you need to post by email). Thanks, Hans

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Re: [pro] help with macro
by karol skocik 26 Sep '11

26 Sep '11

Hi, thanks for help. On Mon, Sep 26, 2011 at 3:02 PM, Scott McKay <swm(a)google.com> wrote: > You're pretty much asking for type inference, but with you > being the one doing the inference. Yes, it's more or less a way to provide more type hints to SBCL. On Mon, Sep 26, 2011 at 4:28 PM, Peter Stirling <peter(a)pjstirling.plus.com> wrote: > You are misunderstanding the way that symbols work: > > First your source code is read by the reader, and symbols are looked up > by their package prefix, or interned in the current package if > unqualified. After this point the raw text that from your lisp file is > thrown away and macro-expansion and compilation is performed using only > the symbols and constants identified/produced by the reader. Since your > macro is trying to shadow symbols rather than generate new ones you only > need to worry about package prefixes at the call site of your macro, and > not in the macro itself > Thanks for explanation. I was confused thinking that reader subsequently reads more of the form as it is expanded, which is rubbish. > :use in defpackage will import all external symbols into the defined > package, and since "+" is external in :cl, and it's highly likely that > you are ":use :cl" it wouldn't need a prefix. > > > (defmacro with-typed-arguments ((name) type &body body) > (let ((func (gensym))) > `(let ((,func #',name)) > (declare (sb-ext:disable-package-locks ,name)) > (macrolet ((,name (&rest args) > (list* 'funcall ',func > (mapcar (lambda (arg) > (list 'the ',type arg)) > args)))) > (declare (sb-ext:enable-package-locks ,name)) > ,@body)))) > > > Should do the expansion you want, but it's not the "right" way in > common-lisp. > Works nicely, thank you! Why do you consider it as not "right"? Have a nice day. Karol > On Mon, 2011-09-26 at 09:31 +0200, karol skocik wrote: >> Hi Lispers, >> I need a help with a following macro I am trying to write: >> >> When the call site looks like this: >> >> (with-typed-arguments (distance) single-float >> (+ (distance a b c d) >> (distance x y z w))) >> >> I want it to expand into something like this: >> >> (+ (DISTANCE (THE SINGLE-FLOAT A) (THE SINGLE-FLOAT B) (THE >> SINGLE-FLOAT C) (THE SINGLE-FLOAT D)) >> (DISTANCE (THE SINGLE-FLOAT X) (THE SINGLE-FLOAT Y) (THE >> SINGLE-FLOAT Z) (THE SINGLE-FLOAT W)))) >> >> Now, what I have currently is: >> >> (defmacro with-typed-arguments ((&rest functions) argument-type &body body) >> (flet ((macrolet-body (fun) >> `(,fun (&rest args) >> `(funcall #',',fun ,@(iter (for arg :in args) >> (collect `(the >> ,',argument-type ,arg))))))) >> `(macrolet (,@(mapcar #'macrolet-body functions)) >> ,@body))) >> >> But it some things I don't understand: >> >> 1.) the function called with typed arguments is called using funcall - >> not a show stopper, just a style issue. Without funcall the expansion >> loops forever since the expansion does not emit the code, but expands >> deeper into infinite recursion of macrolets. Can it be fixed somehow? >> >> 2.) in the flet macrolet-body, I have a trouble understanding ,',fun >> construction next to the funcall - why the "fun" next to funcall can't >> be replaced by macrolet-body argument fun with ,,fun ? It is buried in >> `` but ,,fun there just got me (for call (macrolet-body +)) -> `(,+ >> ...). Let me show my trouble in the example: >> >> In this definition: >> (defmacro with-typed-arguments ((&rest functions) argument-type &body body) >> (flet ((macrolet-body (fun) >> `(,fun (&rest args) >> `(funcall #',,fun ,@(iter (for arg :in args) >> (collect `(the >> ,',argument-type ,arg))))))) >> `(macrolet (,@(mapcar #'macrolet-body functions)) >> ,@body))) >> >> this expansion: >> (with-typed-arguments (distance) single-float >> (+ (distance a b c d) >> (distance x y z w))) >> >> results in this: >> (MACROLET ((DISTANCE (&REST ARGS) >> `(FUNCALL #',DISTANCE >> ;; <- why is there ,DISTANCE when there is `(... `(... ,,fun >> ? >> ,@(ITER >> (FOR ARG :IN ARGS) >> (COLLECT `(THE SINGLE-FLOAT ,ARG)))))) >> (+ (DISTANCE A B C D) (DISTANCE X Y Z W))) >> >> 3.) package-locks - I want it to work with arithmetic functions >> (especially!) defined in CL package. That doesn't work, since I can't >> make a macrolet ((+ (&rest args) ...) because of package-locks. I am >> happy with SBCL specific fix, using SBCL's >> sb-ext:disable-package-locks, or sb-ext:without-package-locks, but I >> can't make it work. >> Especially, I have a trouble understanding, how do I create a symbol >> with package prefix needed in declaration like this: >> (declare (sb-ext:disable-package-locks cl::+)) >> >> Is there a way to prepend the symbol-package and '::' to the given >> symbol? How to construct such fully qualified symbol like cl::+? >> >> Thank you, >> Karol >> >> _______________________________________________ >> pro mailing list >> pro(a)common-lisp.net >> http://lists.common-lisp.net/cgi-bin/mailman/listinfo/pro > > >

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[pro] help with macro
by karol skocik 26 Sep '11

26 Sep '11

Hi Lispers, I need a help with a following macro I am trying to write: When the call site looks like this: (with-typed-arguments (distance) single-float (+ (distance a b c d) (distance x y z w))) I want it to expand into something like this: (+ (DISTANCE (THE SINGLE-FLOAT A) (THE SINGLE-FLOAT B) (THE SINGLE-FLOAT C) (THE SINGLE-FLOAT D)) (DISTANCE (THE SINGLE-FLOAT X) (THE SINGLE-FLOAT Y) (THE SINGLE-FLOAT Z) (THE SINGLE-FLOAT W)))) Now, what I have currently is: (defmacro with-typed-arguments ((&rest functions) argument-type &body body) (flet ((macrolet-body (fun) `(,fun (&rest args) `(funcall #',',fun ,@(iter (for arg :in args) (collect `(the ,',argument-type ,arg))))))) `(macrolet (,@(mapcar #'macrolet-body functions)) ,@body))) But it some things I don't understand: 1.) the function called with typed arguments is called using funcall - not a show stopper, just a style issue. Without funcall the expansion loops forever since the expansion does not emit the code, but expands deeper into infinite recursion of macrolets. Can it be fixed somehow? 2.) in the flet macrolet-body, I have a trouble understanding ,',fun construction next to the funcall - why the "fun" next to funcall can't be replaced by macrolet-body argument fun with ,,fun ? It is buried in `` but ,,fun there just got me (for call (macrolet-body +)) -> `(,+ ...). Let me show my trouble in the example: In this definition: (defmacro with-typed-arguments ((&rest functions) argument-type &body body) (flet ((macrolet-body (fun) `(,fun (&rest args) `(funcall #',,fun ,@(iter (for arg :in args) (collect `(the ,',argument-type ,arg))))))) `(macrolet (,@(mapcar #'macrolet-body functions)) ,@body))) this expansion: (with-typed-arguments (distance) single-float (+ (distance a b c d) (distance x y z w))) results in this: (MACROLET ((DISTANCE (&REST ARGS) `(FUNCALL #',DISTANCE ;; <- why is there ,DISTANCE when there is `(... `(... ,,fun ? ,@(ITER (FOR ARG :IN ARGS) (COLLECT `(THE SINGLE-FLOAT ,ARG)))))) (+ (DISTANCE A B C D) (DISTANCE X Y Z W))) 3.) package-locks - I want it to work with arithmetic functions (especially!) defined in CL package. That doesn't work, since I can't make a macrolet ((+ (&rest args) ...) because of package-locks. I am happy with SBCL specific fix, using SBCL's sb-ext:disable-package-locks, or sb-ext:without-package-locks, but I can't make it work. Especially, I have a trouble understanding, how do I create a symbol with package prefix needed in declaration like this: (declare (sb-ext:disable-package-locks cl::+)) Is there a way to prepend the symbol-package and '::' to the given symbol? How to construct such fully qualified symbol like cl::+? Thank you, Karol

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[pro] Quicklisp's effect on your CL habits
by Zach Beane 25 Sep '11

25 Sep '11

Hi, I've been trying to learn more about how Quicklisp has changed how Common Lisp hackers work. When I posed the question on the Quicklisp list, I got a response from Elliot Slaughter with a point that I hadn't considered before: > I think part of what makes Quicklisp successful (in my opinion) is > that both new *and old* Lisp users love and make use of it. To me, > it's really magical to be able to cd into my project, start lisp, and > quickload it, and have it just work, even if I have customized > versions of some of the dependencies. I think the extent to which > Quicklisp "just works" but also stays out of the way makes older Lisp > hackers happy, which in turn makes the community more vibrant because > library and implementation authors are using the same system that new > users are being told to use (which wasn't always true with e.g. > lisp-starter-pack or asdf-install). As I suspect the "pro" list likely has more old-timers than newcomers, I'd like to get your take on this idea. Zach

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[pro] Test again: please disregard....
by Marco Antoniotti 19 Sep '11

19 Sep '11

Sorry.... -- Marco Antoniotti, Associate Professor tel. +39 - 02 64 48 79 01 DISCo, Università Milano Bicocca U14 2043 http://bimib.disco.unimib.it Viale Sarca 336 I-20126 Milan (MI) ITALY Please note that I am not checking my Spam-box anymore. Please do not forward this email without asking me first.

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[pro] Fwd: Lisp and DSLs
by Ala'a Mohammad 28 Jul '11

28 Jul '11

[oops, I keep forgetting to add cl-pro email when replying.] IMHO: DSL can be made of a varying mix of abstraction, syntax and semantics. All of which can be achieved within CL using interpreter & compiler, macros, closures, reader macros, compiler macros, printing protocol and CLOS. These will help a lot, both the developer and the user. check the following examples: Corman CL Assembler DSL (check the source code for assembler.lisp and how elegantly normal x86 assembler syntax was introduced into CL code) http://www.cormanlisp.com/index.html SBCL VOPs: http://sbcl-internals.cliki.net/Adding%20VOPs http://paste.lisp.org/display/41937 GOAL: Game Object Assembly Lisp ("...intermix assembly instructions seamlessly with higher-level code...") http://www.gamasutra.com/view/feature/2985/postmortem_naughty_dogs_jak_and_… CLSQL: SQL syntax CL-Typesetting: typesetting DSL Prolog interpreter or compiler. those are the ones I remember directly when talking about DSL in common-lisp - Ala'a

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[pro] Lisp and DSLs
by Didier Verna 22 Jul '11

22 Jul '11

Dear friends, I'm starting to write a chapter for an upcoming book on domain specific languages. The chapter is called (tentatively): Extensible languages -- blurring the distinction between DSLs and GPLs GPL meaning General Purpose Language in this context ;-) My intention is to demonstrate how the task of implementing a DSL is made easier when it boils down to an extension or subset of your original GPL (hence reusing its infrastructure), instead of being a totally different language, only written on top of the other. Obviously, I'm going to illustrate this with Common Lisp, and I intend to speak of dynamicity (not only dynamic typing, but in general all things that can be deferred to the run-time), introspection, intersession, structural or procedural reflexivity, meta-object protocols (not sure about this one), macro systems and JIT-compilation. Also, more specifically to Lisp, reader macros (compiler macros maybe?), the condition system (and its ability to *not* unwind) and restarts. Right now, I would like to know if any of you have DSL "pearls", nice examples of DSLs that you have written in Lisp by using some of its features in a clever or elegant way. I would also gladly accept any point of view or comment on what's important to mention, in terms of design principle or anything else, things that I may have missed in the list above. Thank you very much in advance! -- Resistance is futile. You will be jazzimilated. Scientific site: http://www.lrde.epita.fr/~didier Music (Jazz) site: http://www.didierverna.com

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Re: [pro] Lisp and DSLs
by raito＠raito.com 22 Jul '11

22 Jul '11

Or at least learn the difference between a spreadsheet and a database... I see too many spreadsheets used as databases. Neil Gilmore raito(a)raito.com Quoting "Thomas M. Hermann" <thomas.m.hermann(a)odonata-research.com>: If people are going to rely on Excel to the extent that they do, I wish they'd at least learn VBA.

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Re: [pro] Lisp and DSLs
by Alessio Stalla 20 Jul '11

20 Jul '11

On Wed, Jul 20, 2011 at 9:21 PM, Martin Cracauer <cracauer(a)google.com> wrote: > I find that people have a wrong impression of what it means to have a > domain specific language. > > For me, one of the greatest advantages of Lisp is literal data in > code. I don't have to write a complicated parser for some external > data, I don't have to hook up a XML reader library to a bunch of > callbacks and construct a graph or tree or whatever in those callbacks > and then I have to write that graph in XML (ugh) with no programming > help at all unless I pipe it through m4. In Lisp code I just write the > graph, the entire thing, no matter how complicated. And although it > is Lisp source code it doesn't have to live in the source > distribution, I can load an external file later. > > And it gets to use all the Lisp tools I have built for my application > anyway, to help me construct that complicated data structure, without > using m4. > > That does a lof of what many people mean when they say they need a > DSL. What they really want is not to have to do a bazillion lines of > code to hook up the ability to read complex structured real-world > data. I agree, that's one of the greatest advantages of DSLs in Lisp (so called "internal" DSLs) versus "external" DSLs which seem to be getting the most mainstream attention these days, with complex tools to design parsers, editors and whatnot. Without even touching macros, the Lisp reader and printer systems already provide invaluable tools for reading and writing complex data, tools that other languages lack. Macros can then help as a little syntactic sugar, to remove some boilerplate, or to do some bookkeeping, or to move some computation to compile-time (another huge win other languages completely lack). XML, JSON, YAML etc. are so hyped because they introduce a little dynamics in otherwise mostly static languages like Java, but they come with the burden of libraries for parsing, writing, binding to objects, and have trouble expressing shared structure. Besides, in Lisp-based DSLs, it's generally easy or even trivial to escape to Lisp when needed, to use e.g. conditionals or looping, two basic programming language constructs that are lacking (and often missed) in "data-oriented" languages like XML. So, the code = data paradigm is really two-way: you can manipulate code as data, but you can also treat data as part of the code, and the latter point is often neglected. Alessio

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