#clojure log - Jun 21 2009

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0:11 durka42: has anyone seen this while compiling clojure?

0:11 [java] Compiling clojure.inspector to /Users/alex/Programming/clojure/classes

0:11 [java] java.security.AccessControlException: access denied (java.lang.RuntimePermission modifyThread)

0:46 slashus2: durka42: Are you running it inside of a sandbox?

0:54 durka42: slashus2: no, just did a git pull

2:35 stuhood: it's hard to run in a sandbox. or on a beach

2:36 slashus2: stuhood: The sand kind of gives when you run.

4:46 samuels: stuhood: are you stewart holloway

4:46 stuhood: samuels: sorry, no: his nick is stuarthalloway i believe

4:46 ~seen stuarthalloway

4:46 clojurebot: stuarthalloway was last seen quiting IRC, 2134 minutes ago

4:47 stuhood: yea, that's him.

4:47 samuels: ~2134/60

4:47 clojurebot: No entiendo

4:48 samuels: ~(/ 2134 60)

4:48 clojurebot: Excuse me?

4:48 stuhood: samuels: close

4:48 ,(/ 2134 60)

4:48 clojurebot: 1067/30

4:48 samuels: ...

4:48 ,(/ 2134 60.0)

4:48 clojurebot: 35.56666666666667

4:48 samuels: ah ok

4:48 thx

4:48 stuhood: samuels: ratios =)

4:49 samuels: that's a weird aspect to clojure dont you agree

4:49 i mean wtf needs ratios?

4:49 (the wtf in the preceding sentence meaning 'who the f*ck' not 'what the f*ck' )

4:50 stuhood: samuels: not me, heh... but floating point can be difficult to get right, so anytime you can avoid it, you're better off

4:50 wrt accuracy

4:50 samuels: yeah

4:50 stuhood: do you know if clojure will be getting compile time type checking any time soon?

4:51 kotarak: maybe people needing exact numbers, eg. currency or so?

4:51 samuels: and do you konw of any lisp flavours that currently support it?

4:51 kotarak: 1) probably not, 2) Qi

4:52 stuhood: samuels: what he said... but people (Chouser?) are doing work in the area of types, to basically do automatic type hinting based on your imports

4:53 so it seems like a logical next step would be to think about enforcement

4:53 samuels: yeah

4:54 stuhood: what editor do you use for your clojur code?

4:55 stuhood: samuels: vim, with an old version of VimClojure

4:55 samuels: oh ok

4:55 stuhood: do you know if SLIME works with clojure?

4:55 and if it's easy enough to setup?

4:56 stuhood: i believe so

4:56 samuels: great

4:56 stuhood: http://en.wikibooks.org/wiki/Clojure_Programming/Getting_Started#Emacs_.2F_Slime_.2F_Clojure_on_Ubuntu_-_Tutorial

5:02 samuels: thanks

5:02 stuhood: you dont like emacs?

5:03 stuhood: heh... never tried it

5:03 samuels: it's pretty c00l man

5:03 pr3tty*

5:08 stuhood: i probably haven't switched because i'm dumb enough to be up at 5am

5:08 g'night! =)

5:09 samuels: night man!!

10:10 Chousuke: hmm, nobody has bothered to move old issues from contrib to assembla I see

10:10 wonder if it's worth it. :/

10:14 durka42: i got another permissions exception trying to compile contrib.zip-filter.xml

10:25 so the problem is, clojure and contrib now require java 6 to compile!

10:29 does anyone know of a good rss reader that can give me a threaded view of the clojure-dev messages?

10:37 Chousuke: hm

10:59 lenst: java version "1.5.0_19" works for me

11:13 durka42: lenst: interesting, that was the one that threw exceptions for me. what OS?

11:41 krumholt: what is the most used ide with clojure?

11:44 Chouser: krumholt: my guess would be emacs, but I'm not sure. I don't use any.

11:47 rys: Netbeans seems pretty popular from the mailing list

11:47 hoeck: krumholt: I would say emacs + slime, because many of the early clojure adopters had some lisp background

11:53 krumholt: ok thanks

12:17 Chouser: rhickey: can we have a milestore or something for 1.0-bugfix?

12:33 durka42: are any of the ticket comments going to be transferred from GC to Assembla?

12:34 Chousuke: not as comments

12:34 they are included in the description

12:35 but I wonder if someone's going to bother moving contrib issues :P

12:35 should be okay to ignore the closed ones.

12:36 durka42: there is only one then :)

12:36 ~ticket #3

12:36 Chousuke: yeah.

12:36 clojurebot: {:url http://tinyurl.com/mewy4h, :summary "Test ticket", :status :invalid, :priority :normal, :created-on "2009-06-16T19:25:19+00:00"}

12:37 * durka42 was looking at doing it automatically

12:37 durka42: just for fun

12:39 Chousuke: durka42: you'd have to parse google's web pages to do it :P

12:39 durka42: well, maybe

12:39 http://code.google.com/p/clojure-contrib/issues/csv?can=1&q=&colspec=ID%20Type%20Status%20Priority%20Milestone%20Owner%20Summary

12:40 Chousuke: durka42: you'd still need to manually get the comments and patches though :/

12:40 durka42: yeah, that could be a problem :p

12:45 kotarak: Do we now have a Core team?

12:46 durka42: kotarak: bug report for you :)

12:46 kotarak: durka42: I hear.

12:46 eh... I read....

12:46 durka42: *1 is broken

12:48 kotarak: durka42: I see. In the bleeding-edge branch right?

12:49 durka42: yes

12:49 *1, *2, and *3 are all the symbol 'user

12:49 kotarak: It's actually the namespace.

12:49 Try (ns foo.bar)

12:49 durka42: hmm, i see

12:49 i do like the namespace display at the repl prompt though

12:49 kotarak: I know, what the problem is.

13:21 arasoft: Sorry, but I am at the end of Google's wit:

13:21 What do I have to do to get this to work properly at the REPL

13:21 (. "ä" toUpperCase ) (the String contains a lowercase "a umlaut")

13:21 I have tried with different (and none at all) settings for file.encoding and console.encoding, but to no avail.

13:21 Platform is WinXP with German keyboard.

13:21 gnuvince_: ,(.toUpperCase "àé")

13:21 clojurebot: "ÀÉ"

13:22 gnuvince_: ,(.toUpperCase "ä")

13:22 clojurebot: "Ä"

13:22 gnuvince_: Works fine

13:22 arasoft: Not on my machine...

13:22 durka42: Chousuke: http://code.google.com/p/support/issues/detail?id=148

13:23 gnuvince_: arasoft: which OS?

13:24 arasoft: WinXP English with German keyboard

13:24 gnuvince_: arasoft: does cmd.exe input in unicode?

13:29 arasoft: I don't think so, therefore I tried -Dfile.encoding=ISO8859_1 -Dconsole.encoding=Cp1252 and others, but no luck. Even when calling a Java method that returns a hard-coded string with non-ANSI characters, the result is garbage (the specific garbage depends on the specified encodings).

13:29 I looked at http://groups.google.com/group/clojure/browse_thread/thread/1ebe3c8f342f3abe/d0497724d342e27f and similar, but there seems to be no complete solution.

13:32 prospero_: if I want to define a function with a name defined in a string, is there a standard way to do that?

13:33 I've seen an implementation that relies on "new clojure.lang.MultiFn" and defmethod, but it seems like there must be a better way

13:33 arohner: prospero_: you mean you want the name of the function to come from a string?

13:33 prospero_: yes

13:34 arohner: one sec

13:34 maxthimus: from the book programming clojure:

13:34 (defn make-greeter [greeting-prefix] (fn [name] (str greeting-prefix ", " name)))

13:35 (def hello-greeting (make-greeter "Hello"))

13:35 (hello-greeting "world")

13:35 arohner: hrm, this works, but it uses eval

13:36 (eval `(defn (symbol "foo") [x] (* x x))

13:36 prospero_: arohner: eval is ok, I think

13:36 that's what I was looking for, thanks

13:36 Chousuke: you should use a macro. :/

13:37 arohner: yeah, you can write a macro that does the same thing

13:37 Chousuke: (defmacro fn-string [name & the-rest] `(defn ~(symbol name) ~@the-rest)

13:37 arohner: Chousuke: you beat me to it

13:38 that's a better solution

13:38 prospero_: arohner, Chousuke: thanks

13:39 arohner: hmm. macros are a controlled use of eval. that's interesting.

13:39 I never thought of it that way

13:40 Chousuke: well, kind of.

13:42 macros are special in that I don't think there's any other way to run code at macroexpansion (compile) time.

13:43 arohner: if I do (def foo expr...), expr gets run at compile time, right?

13:44 Chousuke: no, it's runtime.

13:44 otherwise, something like (def foo (+ x 1)) would not work :/

13:45 prospero_: so as a followup question, I was looking at this code here: http://github.com/ChickenProp/cloggle/blob/97270c0146a41dc7389a864d333cdaad7986c41b/src/net/philh/cloggle.clj

13:45 which reflects over the opengl libraries, and defines wrapper functions that invoke them

13:46 is he using that method for performance reasons?

13:46 I'm specifically referring to line 72

13:47 arohner: prospero_: it's probably for readability/ to get other features

13:47 Chousuke: that seems a bit hackish

13:49 prospero_: it doesn't seem particularly readable, but ok

13:49 Chousuke: I'm pretty sure what he's doing there should be possible with macros too

13:49 arohner: prospero_: I mean that the functions he creates are more readable than (.invoke foo opengl-context (to-array args))

13:50 Chousuke: Depends on whether it's possible to use reflection in macros.

13:51 arohner: why wouldn't it be possible?

13:51 reflection is just a java method you call

13:51 prospero_: arohner: certainly, but why the 1-to-1 MultiFn/defmethod approach?

13:51 is that functionally different than a defn somehow?

13:53 arohner: no, aside from 1) there is a dispatch fn on multifns, and 2) you can add to the multifn later

13:53 but yeah, I don't see that happening here

13:53 prospero_: ok, extensibility seems like a fair reason

13:55 arohner: hrm, this would be easier to read in my ide

13:55 oh, I get it

13:55 Chousuke: There's probably a better way to do what cloggle does but I can't say it's obvious :/

13:55 arohner: he either gets the existing multi-fn, or creates it if it doesn't exist

13:56 so if that gl-methods returns the same name with different arities, it will create two different methods

13:56 prospero_: hmmm

13:56 that's weird, since as far as I know all opengl functions are suffixed with their parameters

13:57 glVertex3f, glVertex2i, etc.

13:57 Chousuke: perhaps not for the java bindings?

13:57 arohner: step 1 in fixing this would be to get rid of def-ev

13:57 prospero_: I'm no expert, but based on my cursory look at JOGL the names of the functions are unchanged

13:59 arohner: the dispatch function is also interesting

13:59 prospero_: in an ideal world, "vertex" would dispatch to whichever function is appropriate, based on type and arity

13:59 maybe he's building towards that point

14:07 emacsen: I'm redoing my clojure setup and I'n having some (what I'm guessing are) java issues

14:07 I have my clojure jar and I have it on my classpath.

14:08 but when I try to compile contribs, ant says it can't find clojure.jar

14:08 arohner: emacsen: does it work if you do ant -Dclojure.jar=... ?

14:09 emacsen: arohner, yes

14:10 arohner: how are you defining your classpath?

14:11 emacsen: export CLASSPATH=~/local/jars/*

14:11 arohner: the contrib build.xml appears to only pay attention to the -D flag

14:11 emacsen: okay, so that's fine, but then problem 2

14:11 kotarak: If I remember correctly, ant doesn't pay attention to CLASSPATH.

14:12 emacsen: I run clojure thusly: java -cp $PATH_TO_CLOJURE_JAR:$PATH_TO_CONTRIB_JAR clojure.lang.Repl

14:12 for the repl, obviously

14:12 but: user=> (:use clojure.contrib.shell-out)

14:12 java.lang.ClassNotFoundException: clojure.contrib.shell-out (NO_SOURCE_FILE:1)

14:12 clojurebot:

14:13 emacsen: contrib fail

14:14 arohner: hrm, shell-out isn't in my build.xml

14:14 emacsen: the keyboard cat is coming to watch me :)

14:15 ah, lemme check mine

14:15 arohner: in that big list of arg value="clojure.contrib.foo", around line 100

14:15 try adding it and recompiling

14:16 emacsen: it's in mine

14:16 in the <sysproperty key="clojure.compile.path" value="${build}"/>

14:16 arohner: yeah

14:17 emacsen: yeah it's there already

14:18 arohner: did you type (:use clojure.contrib.shell-out) at the repl, or was it part of an ns declaration?

14:18 emacsen: in the repl

14:18 arohner: ah, yeah that won't work

14:18 (use 'clojure.contrib.shell-out)

14:18 or (ns my.package (:use clojure.contrib.shell-out))

14:18 that's kind of confusing

14:19 emacsen: user=> (use 'clojure.contrib.shell-out)

14:19 java.lang.NoSuchMethodError: clojure.lang.Namespace.importClass(Ljava/lang/Class;)Ljava/lang/Class; (NO_SOURCE_FILE:0)

14:20 arohner: hrm, that works for me

14:23 I don't know how to recreate that error message

14:23 emacsen: :-/

14:23 I don't know how not to ;)

14:23 what's your clojure java command line?

14:24 arohner: I just copied what you did. java -cp jars/clojure.jar:jars/clojure-contrib.jar clojure.lang.Repl

14:25 java -cp jars/clojure.jar:jars/clojure-contrib.jar clojure.lang.Repl

14:25 Clojure 1.1.0-alpha-SNAPSHOT

14:25 user=> (use 'clojure.contrib.shell-out)

14:25 nil

14:25 user=> (sh "hostname")

14:25 "kjata.earthlink.net\n"

14:26 emacsen: it fails for me

14:26 clojurebot: for is not a loop

14:26 emacsen: *sigh*

14:27 arohner: what version of clojure are you using?

14:27 emacsen: 1.0.0

14:27 arohner: so you downloaded the tarball, as opposed to svn or git?

14:27 emacsen: I forget

14:28 svn

14:28 arohner: and where did you get contrib from?

14:28 emacsen: svn

14:29 http://clojure-contrib.googlecode.com/svn

14:30 arohner: I would get the latest version of both from git, and make sure the clojure.jar you compile against is the same one you use at runtime

14:30 clojurebot: git

14:30 clojurebot: git is http://www.github.com

14:30 arohner: that's not useful, clojurebot

14:31 http://github.com/richhickey/clojure/tree/master

14:31 http://github.com/richhickey/clojure-contrib/tree/master

14:31 emacsen: I found the git version of clojure to be unstable

14:32 arohner: unstable how?

14:32 emacsen: does git clojure-contrib track git clojure

14:32 I forget

14:32 but it broke for me one time

14:32 arohner: yes, they track

14:50 Lau_of_DK: Question - Ive got a plain-text file on my system, (count (slurp file)) = 1064, (.length (File. file)) = 1078 - Why ?

14:50 Chousuke: Lau_of_DK: maybe its length as characters is not the same as its length in bytes?

14:51 opqdonut: which would be the case with for example UTF-8 encoding

14:51 Lau_of_DK: How could thei differ when its plain text ?

14:51 Chousuke: Lau_of_DK: for example, if you have double-byte characters in it.

14:51 opqdonut: s/would/might/

14:51 Lau_of_DK: s/thei/they

14:51 Chousuke: Lau_of_DK: well, any non-ascii might be double-byte

14:51 Lau_of_DK: alright - I didnt think that occured with plain text files, but I understand that it would naturally be the cause of the problem

15:20 arohner: Lau_of_DK: are you on windows?

15:28 Lau_of_DK: Of course not :)

15:28 arohner: not everyone is so enlightened. :-) I was wondering if \r\n's accounted for your discrepancy

15:30 Lau_of_DK: That might actually be it, I got this from a windows system, and FTP downloaded it, in that process they migt have been stripped

15:30 I think its 1 bytes per linie

17:03 arohner: danlarkin: how do you get clojure-json to print a json symbol?

17:03 i.e. prototype requires "new Ajax.Request(url, {method: 'get',..."

17:04 and if I try to use clojure-json, I end up with {"method":"get" rather than {method:"get"

17:07 Lau_of_DK: I have a clojure program which downloads a couple of files and then parses them. when I run it from the repl, this is a 1 second job, when I run it from command line like "java -cp clojure.jar clojure.lang.Script dl.clj" it takes forever... Its coming up on 5 minutes now and still now result...?

17:10 Chouser: do you use agents or pmap?

17:13 Lau_of_DK: Single threaded

17:15 Chouser: Lau_of_DK: I guess I'd either attach a debugger and break it after a couple seconds to see where it's spending it's time, or...

17:15 sprinkle some println's around to see how far its getting.

17:16 Lau_of_DK: I've already wrapped the calls in a debug macro, and it gets a list of filenames from the server which works fine, then those names are mapped to download-file, and that doesnt even begin

17:17 (map #(do

17:17 (debug "Download message" "OK" (download-message %)) %)

17:17 (debug "Retrieving list of messages" "OK" (get-messages))))

17:17 Sun Jun 21 23:18:10 CEST 2009: Retrieving list of messages

17:17 Sun Jun 21 23:18:10 CEST 2009: OK

17:18 prospero_: a few hours ago I asked about defining a function whose name was passed in as a string

17:18 and was told that the best solution was (defmacro fn-string [name & rest] `(defn ~(symbol name) ~@rest))

17:18 Lau_of_DK: Its interesting, that when run from the REPL, the "Retrieving list of messages" message is never printed, the "Downloading message" is however....?!

17:18 prospero_: which is great if I try (fn-string "square" [x] (* x x))

17:18 Lau_of_DK: (and the opposite is true when run from commandline)

17:18 prospero_: but if I try (def sqr "square")

17:19 and then (fn-string sqr [x] (* x x))

17:19 it will create a function called sqr rather than "square"

17:19 I'm assuming there's something kind of basic about macros I'm missing here

17:19 but have no idea what it is

17:20 opqdonut: you need to eval the first arg

17:21 Chousuke: prospero_: macros can't depend on runtime arguments.

17:21 opqdonut: that is, name

17:21 ah, yeah, in case of def the name needs to be known beforehand

17:21 prospero_: Chousuke: so would eval be the only way to accomplish what I'm trying to do?

17:22 Chousuke: you want to def functions based on some strings you read at runtime?

17:22 prospero_: basically

17:22 Chousuke: are you sure you need global defs? :/

17:23 couldn't you just generate a bunch of functions in a map or something?

17:23 Lau_of_DK: Before we drift too far off (my) topic - Can anybody enlighten me as do why clojure.lang.Repl and clojure.lang.Script seemingly executed clj's differently ?

17:23 prospero_: would that lend itself to a better solution?

17:24 oh, by creating anonymous functions

17:24 right

17:24 Chousuke: yeah, in a map of strings to functions

17:24 prospero_: well, I could do that

17:25 mostly I just wanted to mess around with opengl and cloggle seemed a bit creaky

17:25 Chousuke: the problem with generating global definitions is that you can't use them anyway unless you know that they're going to be there.

17:26 prospero_: right

17:26 I don't know if it's the best solution

17:27 I'm mostly doing this because I'm trying to learn about macros and reflection in java

17:27 Chousuke: cloggle generates bindings, which I guess is one legit reason to generate global defs at runtime, but, you should be able to accomplish the same thing if you do the reflection in a macro and generate the necessary code based on the info you get from the reflection

17:27 it'll be a complex macro though

17:27 prospero_: but I think there's some merit to having named functions that are bindings to the java libs

17:28 wouldn't it just be more straightforward to do an eval, then?

17:28 Chousuke: well, that's basically emulating what the macro would do anyway

17:29 prospero_: but the eval can depend on runtime arguments, correct?

17:29 or are they both limited in that respect

17:29 Chousuke: eval works with runtime stuff, yes.

17:30 but if you're just generating bindings, you might not need them

17:30 reflection should be available during macro expansion time

17:30 prospero_: hmm

17:31 Chousuke: macros are basically functions of a lisp form to clojure code. As long as you return valid clojure code, you can do pretty much anything you want.

17:31 prospero_: so I'd pass the macro a class, and it would do all the reflection inside

17:31 that could be interesting

17:31 Chousuke: you can't pass it the class itself, but you can pass it the name of a class.

17:32 and inside the macro, you can look up the class object using that name with reflection

17:32 at least, in theory. I haven't tried. :/

17:32 prospero_: fair enough

17:33 is there a really good reason to do the more complicated macro approach instead of what seems like a simpler eval approach?

17:33 Chousuke: well, if you manage to pull it off with a macro, I think at the end you would know all you need to know about creating macros :)

17:34 prospero_: ha

17:34 ok, I'll give it a shot

17:34 thanks

17:34 kotarak: prospero_: How do you call the function w/o knowing its name in advance?

17:34 Lau_of_DK: I've figured it out - The REPL (or SLIME) forces evaluation in places where Clojure doesnt

17:34 Chousuke: besides that, I'm not convinced eval is much easier than the macro system

17:35 kotarak: ~eval

17:35 clojurebot: eval is sometimes useful - but only sometimes

17:35 kotarak: -.-

17:35 prospero_: kotarak: I'm playing around with creating bindings to the java opengl libraries

17:35 so I know there's a function called "glVertex3f", for instance

17:36 I'm just trying to skip over some of the indirection necessary to call it, using auto-generated functions

17:36 opqdonut: you can make a macro (export glVertex3f) that expands into (def glVertex3f (something "glVertex3f"))

17:36 by using name etc

17:36 kotarak: prospero_: when you know the name in advance you can convert it to a symbol in advance.

17:37 Lau_of_DK: prospero_: Check out SofiaBA on Github, it seems to me some of the work youre doing, has been done

17:38 prospero_: Lau_of_DK: will do, thanks

17:39 kotarak: you're totally right, I was mostly just looking at cloggle, which does what I'm describing, and thinking that there must be a more elegant way to do it

17:42 Chouser: I'd recommend doing the namespace interning at runtime, rather than trying to force evalueation at compile time.

17:44 Chousuke: prospero_: http://gist.github.com/133660 maybe this'll get you started

17:44 you'll need to do much more complicated reflection to get something useful but it looks like it's possible.

17:45 prospero_: Chousuke: thanks

17:49 Lau_of_DK: When my clojure.lang.Script script has finished, the process lingers for 5 minutes - do you guys forcefully terminate your scripts somehow?

17:51 Chouser: Lau_of_DK: you're absolutely sure you're not starting a an agent somewhere? using future or something?

17:51 Lau_of_DK: 100%

17:51 Its a very straight forward program

17:52 Hmm - There is connection though, which is opened in a global var (kludge) , that qualifies?

17:52 Chouser: Script has only ever lingered for me if one of the agent pools gets going.

17:52 oh, a socket connection? hm... maybe make sure it gets closed?

17:52 Lau_of_DK: lemme try

17:53 That did it :)

18:05 Jetien: hi kotarak! do you have 5 mins? i've got problems with vimclojure...

18:06 kotarak: sure

18:06 Jetien: two problems. first: when i try to load a clojure file which has a (ns ..) form in it i get errors

18:07 kotarak: Jetien: must be on the CLASSPATH

18:07 .. of the server

18:08 Jetien: hm..okay

18:09 second problem: I'm trying to get the snake example to run from within vim: http://java.ociweb.com/mark/clojure/ClojureSnake.html

18:09 kotarak: Jetien: this is a limitation of the dynamic part: it uses Clojure's introspection, which only works, when the file can loaded without problems.

18:10 Jetien: i see

18:11 kotarak: What is the problem with the Snake?

18:11 Jetien: the example works fine when i manually start a repl fromt the console, but not from within the repl from the server. i would to sth like (load-file "snake.clj") and then (com.ociweb.snake/main) and nothing happens

18:11 no errors, nothing

18:12 it's not so much about getting the example to work, but knowing why it isn't working

18:12 kotarak: Does Vim freeze?

18:12 Jetien: no

18:12 kotarak: Hmm...

18:13 Jetien: ..whoops.

18:13 kotarak: whoops?

18:13 Jetien: i accidently lef the channel, nevermind.

18:15 kotarak: Jetien: I must confess, I don't know, why the snake doesn't work.

18:16 I would suspect Vim to freeze, since it waits for input from the server process. But this shouldn't happen until main returns.

18:17 Jetien: have you tried to run the file, too? maybe the error is on my side

18:20 kotarak: doesn't work for me neither...

18:33 gunnarahlberg: what web framework are you guys using? i'm a noob, exploring

18:37 arohner: gunnarahlberg: I'm using compojure

18:38 gunnarahlberg: nice it seems

18:39 arohner: yeah, it works well

18:39 it's a little low-level compared to rails, but what it does, it does well

18:39 and we're building in that direction

18:39 gunnarahlberg: and the deps and install seem really reasonable

21:37 grrrt: hi room! is anyone in to help me with filtering a map to weed out nil values?

21:37 I came up with (reduce (fn [m [k v]] (if (nil? v) m (assoc m k v))) {} {:a 1 :b nil :c 3})

21:38 but I don't know if that's the most Clojure-y way of doing it?

21:38 Chouser: not shabby at all.

21:38 grrrt: heh thanks!

21:39 Chouser: have you looked at 'into'?

21:39 grrrt: hm no.

21:40 (doing (doc into) right now)

21:41 Chouser: what you'd got has nice use of destructuring and reduce.

21:41 grrrt: Ah I see. had a look at the source, it's more readable with recur

21:41 (source for 'into')

21:42 Chouser: do you specifically want only non-nils, or is filtering out false ok too?

21:43 grrrt: in this case I need non-nils, but it's easy to generalise I suppose (defn map-filter or something)

21:44 with false or nil you could do 'if v' instead of 'if (nil? v)' right?

21:47 albino: window 13

21:51 grrrt: hang on... this weed-out-nils is shorter: '(filter (fn [[k v]] (not (nil? v))) {:a 1 :b nil :c 3})'

21:55 danlarkin: arohner: ping

21:57 Chouser: grrrt: yeah, that's why I was asking -- unless you specifically mean to differentiate between nil and false, it's more idiomatic you just say 'if v'

21:59 grrrt: you're right, thanks.

22:00 Actually this was slightly tangential to what I actually wanted to do:

22:00 given maps m1 and m2, return a map with all elements of m2 with keys that exist in m1

22:01 solution is similar: '(filter (fn [[k v]] (contains? m1 k) m2)'

22:17 holmak: grrrt: Check out select-keys

22:18 grrrt: holmak: ah thanks! I suspected there'd be a function for this, it's just a matter of finding the right one :)

22:18 holmak: I just stumbled across it today by accident.

22:19 I've found it's a good habit to read a half-dozen surrounding functions on the Clojure web site for every one you mean to look up.

22:19 It has really paid off for me!

22:20 grrrt: I have the clojure sources permanently open in an editor. The things you learn when you're randomly browsing them!

23:17 bpattison: so why does (str-join "abc" "") return "" -- shouldn't it produce "abc"

23:17 hiredman: ,(doc str-join)

23:17 clojurebot: "clojure.contrib.str-utils/str-join;[[separator sequence]]; Returns a string of all elements in 'sequence', separated by 'separator'. Like Perl's 'join'."

23:18 hiredman: ,(seq "")

23:18 clojurebot: nil

23:18 hiredman: makes sense to me

23:20 bpattison: I must be confused as to what it does

23:20 I'm looking for a method that concat to strings together

23:21 Chouser: ,(str "abc" "123")

23:21 hiredman: ,(doc str)

23:21 clojurebot: "abc123"

23:21 "([] [x] [x & ys]); With no args, returns the empty string. With one arg x, returns x.toString(). (str nil) returns the empty string. With more than one arg, returns the concatenation of the str values of the args."

23:21 hiredman: bpattison: function

23:21 not methods

23:22 bpattison: lol -- okay thanks -- yep str does what I want -- duh I knew that

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