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Search found 488 results on 20 pages for 'lisp'.

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  • How to Create a Temporary Function in Emacs Lisp

    - by Cristian
    I'm making some tedious calls to a bunch of functions, but the parameters will be determined at runtime. I wrote a simple function to keep my code DRY but giving it a name is unnecessary. I don't use this function anywhere else. I'm trying to do it the way I would in Scheme, but I get a void-function error: (let ((do-work (lambda (x y z) (do-x x) (do-y y) ;; etc ))) (cond (test-1 (do-work 'a 'b 'c)) (test-2 (do-work 'i 'j 'k)))) I could stick it all into an apply (e.g., (apply (lambda ...) (cond ...))) but that isn't very readable. Is there a better way?

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  • Please Help me add up the elements for this structure in Scheme/Lisp

    - by kunjaan
    I have an input which is of this form: (((lady-in-water . 1.25) (snake . 1.75) (run . 2.25) (just-my-luck . 1.5)) ((lady-in-water . 0.8235294117647058) (snake . 0.5882352941176471) (just-my-luck . 0.8235294117647058)) ((lady-in-water . 0.8888888888888888) (snake . 1.5555555555555554) (just-my-luck . 1.3333333333333333))) (context: the word denotes a movie and the number denotes the weighted rating submitted by the user) I need to add all the quantity and return a list which looks something like this ((lady-in-water 2.5) (snake 2.5) (run 2.25) (just-myluck 2.6)) How do I traverse the list and all the quantities? I am really stumped. Please help me. Thanks.

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  • Lisp's "some" in Python?

    - by Mark Probst
    I have a list of strings and a list of filters (which are also strings, to be interpreted as regular expressions). I want a list of all the elements in my string list that are accepted by at least one of the filters. Ideally, I'd write [s for s in strings if some (lambda f: re.match (f, s), filters)] where some is defined as def some (pred, list): for x in list: res = pred (x) if res: return res return False Is something like that already available in Python, or is there a more idiomatic way to do this?

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  • memory usage by objects in common lisp

    - by Farzad Bekran
    Is there a way to find out how much memory is used by an instance of a class or basic data types in general? I have a toy webframework in cl that creates and manages web pages with instances of classes that represent the html tags and their properties, and as they are supposed to make an html page, they have children in a slot called children. so I was thinking how much a user's session will cost the server if I take this approach. Thanks.

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  • Dealing with &rest-parameters in common lisp

    - by Patrick
    I want define a functions that accepts &rest - parameters and delegates them to another function. (html "blah" "foo" baz) = "blahfoobaz" I did not find a better way than this one: (defun html (&rest values) (concatenate 'string "" (reduce #'(lambda(a b) (concatenate 'string a b)) values :initial-value "") "")) But this looks somewhat glumbsy to me, since line 4 does no more than concatenating the &rest parameter "values". I tried (concatenate 'string "" (values-list values) "") but this does not seem to work (SBCL). Could someone give me an advice? Kind regards

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  • Equivalence Classes LISP

    - by orcik
    I need to write a program for equivalence classes and get this outputs... (equiv '((a b) (a c) (d e) (e f) (c g) (g h))) => ((a b c g h) (d e f)) (equiv '((a b) (c d) (e f) (f g) (a e))) => ((a b e f g) (c d)) Basically, A set is a list in which the order doesn't matter, but elements don't appear more than once. The function should accept a list of pairs (elements which are related according to some equivalence relation), and return a set of equivalence classes without using iteration or assignment statements (e.g. do, set!, etc.). However, set utilities such as set-intersection, set-union and a function which eliminates duplicates in a list and built-in functions union, intersection, and remove-duplicates are allowed. Thanks a lot!

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  • Merging Two Matrixes... in LISP

    - by abidikgubidik
    (defun merge-matrix (matrix-1 matrix-2) (if (not (or (eql (matrix-rows matrix-1) (matrix-rows matrix-2)) (null matrix-1) (null matrix-2))) (error "Invalid dimensions.")) (cond ((null matrix-1) (copy-tree matrix-2)) ((null matrix-2) (copy-tree matrix-1)) (t (let ((result (copy-tree matrix-1))) (dotimes (i (matrix-rows matrix-1)) (setf (nth i result) (nconc (nth i result) (nth i matrix-2)))) result)))) (merge-matrix '((3 1) (1 3)) '((4 2) (1 1))) * - EVAL: variable NULL has no value I receive an error like that how I can fix the problem, thanks

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  • Trouble converting string/character to byte in lisp

    - by WanderingPhd
    I've some data that I'm reading in using read-line and I want to convert it into a byte-array. babel:string-to-octet works for the most part except when the character\byte is larger (above 200) in which case it returns two numbers. As an example, if the character is ú using babel:string-to-octet returns (195 185) instead of 250 which is what I'm looking for. I tried a number of encodings in babel but none of them seem to work. If I use read-byte or read-sequence it does read in 250. But for reasons of backward compatibility, I'm left with using read-line and I would like to know if there is something I'm missing when using babel:string-to-octet to convert ú to 250. I'm using ccl 1.8 btw.

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  • Is there anyway to "probe" a method in common lisp

    - by Michael Minerva
    My application allows the user to create their own methods indirectly and I later need to refer to these methods. I am wondering if there is a way (for error checking purposes) to test if a method exists without trying to execute it. If I just try and call the method and it doesn't exist this will crash my application.

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  • Finding the maximum number of child nodes in a tree

    - by Jiminizer
    First, I should make it clear that this is required for an academic project. I am trying to find the maximum number of child nodes for any node in a tree, using Common Lisp. My current code is shown below - I'm not 100% on the logic of it, but I feel it should work, however it isn't giving me the required result. (defun breadth (list y) (setf l y) (mapcar #'(lambda (element) (when (listp element) (when (> (breadth element (length element)) l) (setf l (breadth element (length element))) ))) list) l) (defun max-breadth(list) (breadth list (length list)) ) As an example, running (max-breadth '(a ( (b (c d)) e) (f g (h i) j))) should return 4. Does anyone have any ideas where I'm going wrong? I suspect it's related to the second conditional, but I'm not sure.

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  • Executes a function until it returns a nil, collecting its values into a list

    - by Baldur
    I got this idea from XKCD's Hofstadter comic; what's the best way to create a conditional loop in (any) Lisp dialect that executes a function until it returns NIL at which time it collects the returned values into a list. For those who haven't seen the joke, it's goes that Douglas Hofstadter's “eight-word” autobiography consists of only six words: “I'm So Meta, Even This Acronym” containing continuation of the joke: (some odd meta-paraprosdokian?) “Is Meta” — the joke being that the autobiography is actually “I'm So Meta, Even This Acronym Is Meta”. But why not go deeper? Assume the acronymizing function META that creates an acronym from a string and splits it into words, returns NIL if the string contains but one word: (meta "I'm So Meta, Even This Acronym") ? "Is Meta" (meta (meta "I'm So Meta, Even This Acronym")) ? "Im" (meta (meta (meta "I'm So Meta, Even This Acronym"))) ? NIL (meta "GNU is Not UNIX") ? "GNU" (meta (meta "GNU is Not UNIX")) ? NIL Now I'm looking for how to implement a function so that: (so-function #'meta "I'm So Meta, Even This Acronym") ? ("I'm So Meta, Even This Acronym" "Is Meta" "Im") (so-function #'meta "GNU is Not Unix") ? ("GNU is Not Unix" "GNU") What's the best way of doing this?

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  • How can I SETF an element in a tree by an accessor?

    - by Willi Ballenthin
    We've been using Lisp in my AI course. The assignments I've received have involved searching and generating tree-like structures. For each assignment, I've ended up writing something like: (defun initial-state () (list 0 ; score nil ; children 0 ; value 0)) ; something else and building my functions around these "states", which are really just nested lists with some loosely defined structure. To make the structure more rigid, I've tried to write accessors, such as: (defun state-score ( state ) (nth 2 state)) This works for reading the value (which should be all I need to do in a nicely functional world. However, as time crunches, and I start to madly hack, sometimes I want a mutable structure). I don't seem to be able to SETF the returned ...thing (place? value? pointer?). I get an error with something like: (setf (state-score *state*) 10) Sometimes I seem to have a little more luck writing the accessor/mutator as a macro: (defmacro state-score ( state ) `(nth 2 ,state)) However I don't know why this should be a macro, so I certainly shouldn't write it as a macro (except that sometimes it works. Programming by coincidence is bad). What is an appropriate strategy to build up such structures? More importantly, where can I learn about whats going on here (what operations affect the memory in what way)?

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  • Install CLSQL on Mac OS X

    - by Ken
    I have SBCL installed (via macports/darwinports) on my Intel Core 2 Duo Macbook running 10.5.8. I've installed several libraries like this: (require 'asdf) (require 'asdf-install) (asdf-install:install 'cl-who) But when I tried to install CLSQL this way ('clsql) after it downloaded, I got this: ... ; registering #<SYSTEM CLSQL-UFFI {123D9E01}> as CLSQL-UFFI ; $ cd /Users/ken/.sbcl/site/clsql-5.0.5/uffi/; make cc -arch x86_64 -arch i386 -bundle /usr/lib/bundle1.o -flat_namespace -undefined suppress clsql_uffi.c -o clsql_uffi.dylib ld: duplicate symbol dyld_stub_binding_helper in /usr/lib/bundle1.o and /usr/lib/bundle1.o for architecture i386 ld: duplicate symbol dyld_stub_binding_helper in /usr/lib/bundle1.o and /usr/lib/bundle1.o for architecture x86_64 collect2: ld returned 1 exit status collect2: ld returned 1 exit status lipo: can't open input file: /var/folders/Nf/Nf4o5ArDFaWBH2OwtnWM3E+++TQ/-Tmp-//ccJyZxou.out (No such file or directory) make: *** [clsql_uffi.so] Error 1 Is there something I forgot, or some trick to get it to build on Mac OS X? I know very little about C libraries on the Mac these days, so I don't even know where to start on this. Thanks!

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  • How to write (simple) macro?

    - by krzysz00
    I need to write a macro (with-hooks (monster method who what) &body body) for a game I'm writing. Monster is a CLOS object, method and who are strings and what is a function (#' notation). The macroexpansion would be something to the effect of (add-hook monster method who what) ,@body (remove-hook monster method who) I have absolutely no idea how to write such a macro, and I would appreciate some help.

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  • CLIM tutorial, where?

    - by krzysz00
    I am thinking of using McClim for an application, where can I find a tutorial that covers buttons, keyboard/mouse I/O, drawing images, etc. STFW for mcclim tutorial and clim tutorial didn't help much. Any pointers? If such a tutorial doesn't exist, please point that out and I';; try to RTFM (maybe eventually write such a tutoriial)

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  • [org-mode]: repeating task in every Mon, Wed, Fri at 18:00, need help with sexp.

    - by zeroDivisible
    Hello, As I had written in title, I need a little help with improvement of this sexp: * TODO remeber about thingie. SCHEDULED: <%%(or (= 1 (calendar-day-of-week date)) (= 3 (calendar-day-of-week date)) (= 5 (calendar-day-of-week date)))> Now it shows itself in the following days, but I would like to change two things about it: How can I also schedule on specific hours (i.e. 18:00 - 20:00) in the following days How can I made this task repeat itself, just like it repeats itself with <2010-05-13 Wed +1w> (by repetition I mean something like it automatically logs the closing date and time and comes back to the TODO state). I will be grateful for any help. Best regards, Mike.

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  • Data structures in functional programming

    - by pwny
    I'm currently playing with LISP (particularly Scheme and Clojure) and I'm wondering how typical data structures are dealt with in functional programming languages. For example, let's say I would like to solve a problem using a graph pathfinding algorithm. How would one typically go about representing that graph in a functional programming language (primarily interested in pure functional style that can be applied to LISP)? Would I just forget about graphs altogether and solve the problem some other way?

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  • Why isn't there a good scheme/lisp on llvm?

    - by anon
    There is Gambit scheme, MIT scheme, PLT scheme, chicken scheme, bigloo, larceny, ...; then there are all the lisps. Yet, there's not (to my knowledge) a single popular scheme/lisp on LLVM, even though LLVM provides lots of nice things like: easier to generate code than x85 easy to make C ffi calls ... So why is it that there isn't a good scheme/lisp on LLVM?

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  • My first Lisp macro; is it leaky?

    - by Tom Martin
    I've been working through Practical Common Lisp and as an exercise decided to write a macro to determine if a number is a multiple of another number: (defmacro multp (value factor) `(= (rem ,value ,factor) 0)) so that : (multp 40 10) evaluates to true whilst (multp 40 13) does not The question is does this macro leak in some way? Also is this "good" Lisp? Is there already an existing function/macro that I could have used?

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  • What does it mean that "Lisp can be written in itself?"

    - by Mason Wheeler
    Paul Graham wrote that "The unusual thing about Lisp-- in fact, the defining quality of Lisp-- is that it can be written in itself." But that doesn't seem the least bit unusual or definitive to me. ISTM that a programming language is defined by two things: Its compiler or interpreter, which defines the syntax and the semantics for the language by fiat, and its standard library, which defines to a large degree the idioms and techniques that skilled users will use when writing code in the language. With a few specific exceptions, (the non-C# members of the .NET family, for example,) most languages' standard libraries are written in that language for two very good reasons: because it will share the same set of syntactical definitions, function calling conventions, and the general "look and feel" of the language, and because the people who are likely to write a standard library for a programming language are its users, and particularly its designer(s). So there's nothing unique there; that's pretty standard. And again, there's nothing unique or unusual about a language's compiler being written in itself. C compilers are written in C. Pascal compilers are written in Pascal. Mono's C# compiler is written in C#. Heck, even some scripting languages have implementations "written in itself". So what does it mean that Lisp is unusual in being written in itself?

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  • XSLT and possible alternatives [on hold]

    - by wirrbel
    I had a look at XSLT for transforming one XML file into another one (HTML, etc.). Now while I see that there are benefits to XSLT (being a standardized and used tool) I am reluctant for a couple of reasons XSLT processors seem to be quite huge / resource hungry XML is a bad notation for programming and thats what XSLT is all about. It do not want to troll XSLT here though I just want to point out what I dislike about it to give you an idea of what I would expect from an alternative. Having some Lisp background I wonder whether there are better ways for tree-structure transformations based upon some lisp. I have seen references to DSSSL, sadly most links about DSSSL are dead so its already challenging to see some code that illustrates it. Is DSSSL still in use? I remember that I had installed openjade once when checking out docbook stuff. Jeff Atwood's blog post seems to hint upon using Ruby instead of XSLT. Are there any sane ways to do XML transformations similar to XSLT in a non-xml programming language? I would be open for input on Useful libraries for scripting languages that facilitate XML transformations especially (but not exclusively) lisp-like transformation languages, or Ruby, etc. A few things I found so far: A couple of places on the web have pointed out Linq as a possible alternative. Quite generally I any kind of classifications, also from those who have had the best XSLT experience. For scheme http://cs.brown.edu/~sk/Publications/Papers/Published/kk-sxslt/ and http://www.okmij.org/ftp/Scheme/xml.html

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  • F# vs Haskell vs Lisp - which language to learn?

    - by empi
    I've heard a lot about functional programming languages and I'm willing to learn one. I guess it will be mostly for fun, however, I hope it will improve my programming skills. I have mostly C#/.NET background, so my first choice is to learn F# (because of .NET and familiarity with Visual Studio). On the on other hand, I wonder if F# has features like Lisp macros or Haskell higher order functions. Could you compare F#, Haskell and Lisp? Which one will be the language of your choice?

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