#clojure log - May 30 2015

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0:02 randomcharhere: One issue yeh will run into is if you change yer game object you will have change all the fuctions would create an itermediate function that talks to all the other functions that way yeh end only having to modify one fuction?

0:19 escherize: The best approach I've seen for managing a big-ass-state-map is re-frame, It's a clojurescript library that's got a simple idea that wouldn't be hard to implement in clojure.

0:27 dumptruckman: escherize: thanks, i'll look into it

0:27 escherize: otherwise i basically have to deal with the big-ass-state-map yeah?

0:58 ambrosebs: where does lein repl call complete.core/completions?

0:59 ah I think this is the code that gets injected https://github.com/trptcolin/reply/blob/69c4c6ffe0c8903a193c1e127337832e225335b0/src/clj/reply/reader/jline/completion.clj#L6-L7

2:32 escherize: dumptruckman: you might want to take a look at spectre for maintaining a big map if swap reset and update-in feel like not enough

3:26 elvis4526: I'm trying to use httpkit and websocket and with-channel isn't working.

3:26 within (with-channel req channel), channel is always nil.

7:28 ionthas_: dumptruckma: "It's better to have 100 functions operate in one datset insted of having 10 functions operating in 10 differents datasets." You should check atoms, they will allow to change the state of your big object. Maybe there is a better way to do it, but I'm also a principant.

7:34 irctc: what is the super class of map list String seq ...?

7:37 oddcully: Object?

9:16 franklnrs: join #bouncetest

9:20 gfredericks: irctc: "map list String seq ..." isn't a class?

10:34 virmundi: hello. Is there anyone active in here?

10:35 I’ll give it a shot. I need to get a File from the tests/ dir of the project. I cannot figure out how to get that without handing a full path. I need a File and not a stream.

10:38 luxbock: virmundi: might (java.io.File. (.getCanonicalPath (java.io.File. ".")) "/tests/") work?

10:39 virmundi: let me see.

10:39 luxbock: (java.io.File. (str (.getCanonicalPath (java.io.File. ".")) "/tests/file.thing"))

10:40 virmundi: yes, yes it did. now I wonder why (io/file didn’t)

10:41 luxbock: replacing java.io.File. with io/file should work exactly the same

10:41 justin_smith: luxbock: isn't that the same as (java.io.File. "./tests/") - it should be

10:41 virmundi: I added a new resources directory under test and updated the lein profiles.clj to work.

10:42 luxbock: justin_smith: oh right!

10:42 virmundi: you’re right. tempfile2 (io/file "./test/resources/20150429_102332.jpg")

10:42 thanks

10:43 justin_smith: virmundi: here's another neat trick --

10:43 ,(java.io.File. "foo" "bar")

10:43 clojurebot: #object[java.io.File 0x1a442294 "foo/bar"]

10:43 justin_smith: no need to use str either :)

10:44 virmundi: :)

10:48 gfredericks: ,(java.io.File. "foo/bar" "baz/kabling")

10:48 clojurebot: #object[java.io.File 0x3bd2c1b4 "foo/bar/baz/kabling"]

10:58 drivercache: Should i learn java before learning clojure?

10:58 I am new.

10:58 SagiCZ: drivercache: not super necessary i would say

10:58 virmundi: no. As a guy who literally has a Java ring on as I type this, you don’t need it.

10:58 http://s.hswstatic.com/gif/digital-jewelry-javaring.jpg

10:58 SagiCZ: drivercache: may help to read up about the very basics.. but you dont need to dive deep into inheritence, oop etc

10:59 justin_smith: drivercache: it suffices to know just enough so that javadoc is readable - you really don't need to get the syntax, but the semantics are helpful

11:00 virmundi: drivercache: the viewpoints are different. you can write clean code in java with out concern for much mutation (final for all vars), but clojure makes the same easier.

11:00 SagiCZ: virmundi: not entirely true.. its not as simple as slapping final on attributes.. clojure goes a long way towards immutability

11:00 virmundi: I agree. I was just saying.

11:00 justin_smith: virmundi: well... a final collection is still mutable, even if its field is final - so you do need immutable collections

11:01 SagiCZ: i think there are some java libraries for immutable collections.. probably not as efficient as in clojure

11:01 justin_smith: SagiCZ: clojure is a good java lib for immutable collections :)

11:02 virmundi: justin_smith: I’m saying you can do it in Java, but you’re going to get into some niche corners of Java development. Heck, using final is so odd for most developer I’ve been actually told to remove them because they make the code harder to read.

11:02 SagiCZ: justin_smith: interesting point! maybe some java coders could only use that part of clojure

11:02 virmundi: seriously? thats just non-sensical, who told you that? final is appropriate in many cases and it may make the code way faster

11:03 virmundi: sagicz: a very poor programmer during a code review. I ignored her and then had a 20 minute conversation about code quality with the project manager.

11:04 SagiCZ: virmundi: i see!

11:04 anyways whats up with clojure lately? is it still being developed? where is 1.7.0? is clojure losing momentum?

11:04 virmundi: sagicz: in the end, I got to keep the finals.

11:05 justin_smith: SagiCZ: 1.7 has a release cantidate, and might be the most feature rich addition we've had in a long while

11:05 might be comparable to the 1.2 -> 1.3 update

11:06 SagiCZ: justin_smith: and would you call clojure's future bright? i understand it will never become mainstream engine, but it needs to have a solid community so it wont die out. I hate to start a big project only to find that the tools I use get deprecated in the next year

11:06 s/engine/language

11:06 justin_smith: I don't see any signs of that myself

11:07 SagiCZ: this is interesting though https://www.google.cz/trends/explore#q=clojure%2C%20golang&cmpt=q&tz=

11:07 keyword trend comparison

11:08 justin_smith: anyways, thanks.. thats mostly what i wanted to hear

11:08 justin_smith: clearly, if we want it to succeed, cognitect has to hand clojure over to bing

11:09 SagiCZ: I think the mailing list (available on google groups) gives a good idea of the state of development (both for the language and libs) - things tend to get announced or decided there

11:10 SagiCZ: justin_smith: i see.. well being quite young and from a Windows background I always found mailing-list bizzare and unproductive communication of the past.. almost like using mailing pidgeons.. so I guess thats why I didnt catch the latest development. thanks

11:11 justin_smith: SagiCZ: the UI on google groups makes it more like a web forum

11:11 SagiCZ: btw cognitect? is clojure developed by private company now<

11:11 ?

11:11 justin_smith: SagiCZ: always has been

11:11 it accepts contributions

11:12 SagiCZ: didn't know that

11:12 justin_smith: that's why you have to sign the super official agreement and use jira if you want to submit code for clojure

11:13 SagiCZ: well I don't think it's a bad idea at all..

11:13 seems like clojure's development is fueled by Datomic and other cognitect products

11:13 justin_smith: they also offer clojure consulting

11:20 drivercache: SagiCZ: I have working knowledge of python, will it be enough to begin?

11:21 SagiCZ: drivercache: nothing is enough to begin

11:21 if you learned python, you can learn clojure

11:21 just note that functional programming is very different from imperative (python) and the transition might be difficult at first

11:25 gfredericks: hello

11:30 virmundi: hi

11:31 luxbock: I have a debug-printing helper library that currently just formats text nicely and prints it to the REPL

11:32 I thought it might be a good idea to offer alternative output targets

11:32 justin_smith: luxbock: you should check out aviso/pretty and aviso/tracker

11:32 for prior art

11:32 luxbock: i.e. you could print to a file, create a HTML page or an org document

11:32 justin_smith: this is mine: https://github.com/luxbock/pr-foobar

11:32 I think they do different things

11:33 justin_smith: pretty is for things like column alignment and colors

11:33 tracker is for being able to show a context for errors that makes sense for clojure code

11:33 luxbock: my goal is that switching from the core-function to the pr-equivalent should be as painless as possible

11:33 justin_smith: OK

11:34 luxbock: so to switch the output function, I was thinking of making a dynamic variable that holds it

11:34 and then just use alter-var-root to change it

11:34 is this a good idea?

11:34 justin_smith: if you are using alter-var-root, why make the var dynamic?

11:34 luxbock: ah yeah I guess I wouldn't need to

11:43 virmundi: what am I doing wrong here: (io/copy (:tempfile file) dest-file)

11:43 (:tempfile is a valid file). dest-file is a new file.

11:44 SagiCZ: :tempfile cant be a valid file, it is a keyword

11:44 virmundi: file is a map

11:44 (:key m) == value?

11:44 SagiCZ: yes that is correct

11:45 virmundi: dest-file is new. But I’m getting a error actual: java.io.FileNotFoundException: /Users/jdavenpo/Pictures/tours/usa/fl/palatak/uuid/newfile.jpg

11:46 SagiCZ: well.. seems like the fild is not on that path

11:49 virmundi: (is (.exists tempfile))

11:49 where tempfile is the value in the map :tempfile

11:49 SagiCZ: that returns true?

11:49 virmundi: yep

11:49 SagiCZ: you can lose the "is" btw

11:50 virmundi: the temp file is classpath relative.

11:50 I can in a test?

11:50 SagiCZ: no no.. not in a test

11:50 sorry

11:50 virmundi: np.

11:50 SagiCZ: tahts really weird.. because the jvm can access the file but then says its not found? strange

11:50 virmundi: The error is the new file.

11:51 SagiCZ: oh..

11:51 virmundi: (defmethod move :tour-list [file]

11:51 (let [dest (create-dest file)

11:51 dest-file (io/file dest)]

11:51 (io/copy (:tempfile file)

11:51 (io/file dest))

11:51 dest))

11:51 SagiCZ: then maybe then you dont have write acces on the path

11:51 justin_smith: virmundi: don't do that please

11:51 virmundi: sorry, best way to do that?

11:51 SagiCZ: www.refheap.com

11:51 justin_smith: use a site like refheap

11:51 yeah

11:51 virmundi: https://www.refheap.com/101885

11:53 the blow out is on line 5, as per the refheap

11:53 the declaration at line 3 is for debugging.

11:53 SagiCZ: virmundi: would like to help you but i rly dont know whats wrong there

11:54 Chousuke: does the directory structure exist+

11:54 ?

11:54 virmundi: :(

11:54 Chousuke: File won't automatically create you directories.

11:54 SagiCZ: yeah all the folders must exist before creating a new file

11:55 justin_smith: there's a method that creates all the nested folders you need for a given path though iirc

11:56 virmundi: .mkdir executes without creating the paths.

11:56 justin_smith: .mkdirs

11:57 "Creates the directory named by this abstract pathname, including any necessary but nonexistent parent directories."

11:57 you were missing the plural s

11:57 .mkdir only creates a single directory, where the parent must already exist

11:58 .mkdirs creates all the directories needed fora given file

11:58 virmundi: :O

12:04 so then maybe a bit of Java is required for Clojure?

12:04 justin_smith: virmundi: like I said, you should at least know how to read the javadoc

12:05 but that's not java - you're not using java syntax. But we use the same vm and the same methods, so that ends up being something you should at least know how to look up.

12:06 virmundi: ;)

12:06 That was it.

12:06 I had to get the parent dir of the new file, but worked fine.

12:06 thanks

12:07 justin_smith: virmundi: I find the "javadoc search pane" browser plugin really useful

12:08 it detects when you are looking at a javadoc page, and makes a pane with real-time completion and search

12:08 SagiCZ: i would rather see the javadoc in my IDE than having to switch to browser

12:09 justin_smith: SagiCZ: I don't want to read javadoc in emacs myself

12:09 SagiCZ: i understand..

12:10 i am very sensitive to my tool chain and i understand others may be as well so that can be left for personal preference

13:13 luxbock: one thing I've started doing lately with destructuring is to always use :as even when it's not strictly needed

13:13 but I think it makes it easier to read the code, because the name can give a hint to what the argument/local is supposed to do

13:13 anyone else do this?

13:21 gfredericks: I don't because it looks like a mistake

13:22 but I appreciate the desire for documentation

13:22 clojure currently conflates the local names of args with documentation for the args

13:22 justin_smith: see also using prismatic/schema but not running the checks

13:22 but using the declarations as a form of docs

13:23 gfredericks: I wish there were a standard way to add arg documentation

13:23 justin_smith: yeah, exactly

13:23 metadata on args?

13:23 gfredericks: the drawback is

13:23 luxbock: gfredericks: ditto

13:23 gfredericks: you sometimes have multiple arglists

13:23 which might be irrelevant to the documentation

13:23 ,(doc +)

13:23 clojurebot: "([] [x] [x y] [x y & more]); Returns the sum of nums. (+) returns 0. Does not auto-promote longs, will throw on overflow. See also: +'"

13:24 justin_smith: gfredericks: first class code accessible arglist objects, with first class code accessible arg objects

13:24 gfredericks: what

13:24 justin_smith: so you could do like (-> #'+ :arglists first :args first :doc)

13:24 never mind that's crazy

13:25 gfredericks: I would suggest :doc/args metadata on the var

13:25 related, you could also add examples as metadata

13:25 i.e., as first-class code rather than in a docstring

13:25 which could additionally be subject to automatic validation

13:25 justin_smith: tests can already be specified this way

13:26 gfredericks: yeah

13:26 well

13:26 sort of

13:26 ,(doc test)

13:26 clojurebot: "([v]); test [v] finds fn at key :test in var metadata and calls it, presuming failure will throw exception"

13:26 gfredericks: ^ it looks for a fn, not a form

13:26 justin_smith: ahh

13:26 yeah that is different

13:27 gfredericks: and you have to throw exceptions :/

14:11 does anybody know an elisp way to check if the current buffer is a file that is in the project that the default cider connection is a part of?

14:11 I assume any solution has to be super hacky

14:12 clojer: I have a (let .... form containing 2 non-nested (for ... comprehensions. Only the last one seems to execute even if I wrap them both in a (do ... block which shouldn't be necessary in a (let ... form.

14:17 justin_smith: ~for

14:17 clojurebot: for is a beautiful person

14:18 justin_smith: clojer: sorry, I wanted a different factoid. for is lazy

14:18 use doseq if you are not consuming the result

14:18 it's almost identical, but returns nil and is not lazy

14:18 ,(do (for [a (range 10)] (println a)) nil)

14:18 clojurebot: nil

14:19 clojer: justin_smith: Why does only the last for comp execute?

14:19 justin_smith: ,(do (doseq [a (range 10)] (println a)) nil)

14:19 clojurebot: 0\n1\n2\n3\n4\n5\n6\n7\n8\n9\n

14:19 justin_smith: clojer: laziness

14:19 notice the difference between what for and doseq did above

16:05 fourq: I'm reading up on persistent vectors and their inner workings. If someone could speak to this image, specifically what it means when it says "path copying". The way I interpret this is that the new vec, the blue one, created 3 new internal nodes, 1 new leaf node, and then pointed the left internal node to the existing, old, vector. Where does "path copying" come into play here? http://screencast.com/t/ZG4igyaPHS7

16:25 bmorphism: Is output-stream with lazy-seq the solution if I want to output the results of a computation into a file and not keep them in memory?

17:21 underplank: So I have this (def scripts-path (str (io/resource "test/scripts") "/"))

17:21 which gives me "file:/Users/mlakewood/Projects/orochi/resources/test/scripts/"

17:21 hoe do I get just the string representation without the file: on there

17:22 *how

17:28 justin_smith: underplank: (.getPath (io/resource "test/scripts"))

17:28 you don't need to add the / yourself

17:29 underplank: Oh great! I’d worked out that I needed to get a java url and then do getPath on it.. but didnt realise that I could just call getPath on the return. Makes sens.

17:29 thanks justin_smith helpful as always!

17:42 jtmarmon: hey guys

17:43 i have a fairly large threaded macro that fails macro expansion whenever I add "..." to one of the forms...if i remove it it succeeds. the compilation error is "CompilerException java.lang.StringIndexOutOfBoundsException: String index out of range: 0"

17:43 just having ... anywhere in the macro makes it fail with that error. it's quoted just fine as far as i can tell. super weird

17:44 justin_smith: wait, what does 'add "..." to one of the forms' mean exactly?

17:44 like one of the forms has "..." in it?

17:44 the string?

17:44 jtmarmon: yep

17:44 no

17:44 the characters ...

17:44 not in a string

17:44 the form is quoted

17:45 justin_smith: even if quoted, I don't think ... is valid - it's not a valid symbol or symbol constituent. There may be contexts where it works accidentally.

17:45 ,'...

17:45 clojurebot: ...

17:46 jtmarmon: it's for a datomic collection binding

17:46 justin_smith: OK

17:46 funny, ... actually works as a symbol, but I didn't expect it to

17:47 jtmarmon: http://puu.sh/i6pA9/97aa45aa3f.png

17:50 TEttinger: ,(let [... "wat"] ...)

17:50 clojurebot: #error {\n :cause "Illegal field name \"...\" in class sandbox$eval49"\n :via\n [{:type clojure.lang.Compiler$CompilerException\n :message "java.lang.ClassFormatError: Illegal field name \"...\" in class sandbox$eval49, compiling:(NO_SOURCE_PATH:0:0)"\n :at [clojure.lang.Compiler analyzeSeq "Compiler.java" 6740]}\n {:type java.lang.ClassFormatError\n :message "Illegal field name \"...\" in ...

17:50 TEttinger: hm

17:50 justin_smith: ,(def ... "this works")

17:50 clojurebot: #'sandbox/...

17:51 justin_smith: ,...

17:51 clojurebot: "this works"

17:51 TEttinger: whaaaaat

17:51 justin_smith: TEttinger: yeah, I know, right?

17:51 that's why my first instinct was that it only worked accidentally

17:51 TEttinger: (inc wat)

17:51 lazybot: ⇒ 3

17:51 TEttinger: how doe sthat have 3

17:51 justin_smith: TEttinger: I think it's because vars are not used as method or field names

17:52 TEttinger: if only our incs left metadata we could look up on the karma :)

17:52 TEttinger: haha

17:52 lazybot could even dump to refheap

17:56 justin_smith: ,(def watset (hash-set Double/NaN Double/NaN Double/NaN))

17:56 clojurebot: #'sandbox/watset

17:56 justin_smith: ,watset

17:56 clojurebot: #{NaN NaN NaN}

17:56 justin_smith: ,(get watset Double/NaN)

17:56 clojurebot: nil

17:56 justin_smith: ,(get watset (first watset))

17:56 clojurebot: NaN

17:56 justin_smith: roflmao

17:58 * TEttinger asplode

18:02 justin_smith: ,(= watset (hash-set Double/NaN Double/NaN Double/NaN))

18:02 clojurebot: false

18:02 justin_smith: ,(= watset (apply hash-set watset))

18:02 clojurebot: true

18:02 TEttinger: haha

18:02 ,(count watset)

18:02 clojurebot: 3

18:03 TEttinger: ,(distinct watset)

18:03 clojurebot: #<UnsupportedOperationException java.lang.UnsupportedOperationException: nth not supported on this type: PersistentHashSet>

18:03 TEttinger: oh?

18:03 justin_smith: ,(distinct (seq watset))

18:03 clojurebot: (NaN NaN NaN)

18:03 TEttinger: ,(distinct (seq watset))

18:03 clojurebot: (NaN NaN NaN)

18:03 TEttinger: haha

18:03 justin_smith: TEttinger: it's like we found the weirdest insect ever under a rock, and now we just can't stop poking it

18:03 TEttinger: haha

18:04 justin_smith: let's see what it does if we put it in a jar with a spider

18:04 TEttinger: I was going to link to a solifugid, but oh god those things are terrifying

18:05 justin_smith: is that the same as a camel spider?

18:05 TEttinger: here's a better weird bug, it's nice https://flic.kr/p/cu62MQ

18:05 not sure

18:06 I think sun spiders

18:06 justin_smith: $google solifugid

18:06 TEttinger: I don't like house centipedes for totally different reasons

18:06 lazybot: [Solifugae - Wikipedia, the free encyclopedia] http://en.wikipedia.org/wiki/Solifugae

18:06 justin_smith: "known variously as camel spiders, wind scorpions, sun spiders, or solifuges"

18:06 TEttinger: (as in, if you hit a house centipede with, say, your shoe, its legs fly off and KEEP MOVING)

18:06 justin_smith: heh

18:07 very similar in nature to a set full of multiple NaNs

18:07 TEttinger: yes

18:07 it is what should not be

18:55 sdegutis: Is there anything Clojure can't do that Haskell can, aside from the restrictions and type-checking errors Haskell provides?

18:56 gfredericks: it's probably easier to call C code in haskell?

18:57 sdegutis: Okay but any algorithmic type things?

18:57 Like, can Clojure implement monads?

19:01 justin_smith: there are monadic libraries for clojure, but since we don't have easy type inference or strong type requirements they usually don't end up being especially useful

19:05 sdegutis: Ah I see.

19:06 Thanks guys.

19:06 Welp, back to cleaning up the mess I made in our codebase at work.

19:06 gfredericks: sdegutis: actually yeah monads are a good point -- you can't straightforwardly write polymorphic 0-arg functions that monads in haskell depend on

19:07 I think this is the main reason why trying to write a monad library in clojure is pretty awkward

19:08 justin_smith: gfredericks: even using one is a bit weird

19:08 gfredericks: I've never tried

19:09 sdegutis: gfredericks: Oooh, that explains it.

19:09 Because in Clojure, polymorphism requires at least one argument.

19:09 gfredericks: yep

19:09 sdegutis: In Haskell, it can be based on type, which is like an implicit argument almost.

19:09 gfredericks: can't write (return x) or (pure x) or whatever

19:09 sdegutis: Got it.

19:09 gfredericks: so you could A) require everybody to pass "the monad" around, in which case nobody will want to use your library

19:10 B) do something magical with macros or dynamic vars or something, in which case nobody will want to use your library

19:10 C) don't bother writing a monads library, in which case nobody will want to use your library

19:11 if bbloom were here he would argue that monads aren't very useful anyhow

19:11 * bbloom didn't read any of the above discussion

19:11 bbloom: just use a lazy seq and write an interpreter for that seq w/ reduce

19:11 * bbloom leaves now

19:12 sdegutis: Oooh, of course!

19:12 bbloom: why not transducers?

19:12 gfredericks: he didn't say not transducers

19:12 sdegutis: bbloom: I was under the impression that transdocers completely obsolete your solution.

19:12 gfredericks: I thought transducers and lazy seqs were incompatible?

19:13 gfredericks: not at all

19:13 * sdegutis actually has no idea how most stuff in Clojure works

19:13 bbloom: s/lazy seq/whatever-ducable/

19:13 * bbloom leaves for real now

19:13 gfredericks: ,(doc sequence)

19:13 clojurebot: "([coll] [xform coll] [xform coll & colls]); Coerces coll to a (possibly empty) sequence, if it is not already one. Will not force a lazy seq. (sequence nil) yields (), When a transducer is supplied, returns a lazy sequence of applications of the transform to the items in coll(s), i.e. to the set of first items of each coll, followed by the set of second items in each coll, until any one of the co...

19:14 gfredericks: hmm

19:14 ,(sequence (map inc) [1 2 3])

19:14 clojurebot: (2 3 4)

19:14 gfredericks: ,(type (sequence (map inc) [1 2 3]))

19:14 clojurebot: clojure.lang.LazySeq

19:14 gfredericks: ,(sequence (map inc) (range 5))

19:14 clojurebot: (1 2 3 4 5)

19:14 * sdegutis misses Ruby a lot right now, oddly enough

19:14 gfredericks: ^ lazy seq in, lazy seq out, w/ transducers

19:15 * justin_smith goes and implements method-missing for clojure

19:15 gfredericks: did refinements ever make it to ruby 2?

19:20 sdegutis: I think I prefer objects, classes, and dot-notation.

19:20 gfredericks: you've been saying that for weeks now I think

19:20 sdegutis: I have? I thought this was the first time.

19:20 gfredericks: okay I'll stop conversing I guess

19:21 sdegutis: wat

19:22 I don't see the connection from everything before that to that.

19:23 gfredericks: I assumed you were trolling because most of your conversation lately has been about OOP

19:28 I was tripped up by the difficulty of telling intentions via text; my apologies

19:29 sdegutis: :|

19:34 I guess I'm just coming to this same conclusion over and over because I've made a mess of my codebase by trying to design our system with just pure functions, which has a lot of drawbacks.

19:39 gfredericks: how much legacy ruby have you dealt with?

19:40 sdegutis: gfredericks: plenty

19:40 gfredericks: I'd say this is worse.

19:43 Neat how in Datomic a bool value can be true false or nil.

19:44 I am taking advantage of that right now in my code.

23:35 dumptruckman: how do i join together lists into one list?

23:35 justin_smith: dumptruckman: concat

23:35 dumptruckman: ah, thanks

23:36 justin_smith: ,(concat (range 3) (range 3))

23:36 clojurebot: (0 1 2 0 1 ...)

23:38 dumptruckman: is there some way to do this with destructuring?

23:38 (concat (for [player (:players entites)] (:segments player)))

23:38 justin_smith: no

23:39 I mean there is apply concat

23:39 dumptruckman: actually i'm not even sure that's right >.>

23:39 justin_smith: or mapcat

23:39 ,(apply concat (for [a {:a [0 1]} {:a [:b :c]}] (:a a)))

23:39 clojurebot: #error {\n :cause "for requires an even number of forms in binding vector in sandbox:"\n :via\n [{:type clojure.lang.Compiler$CompilerException\n :message "java.lang.IllegalArgumentException: for requires an even number of forms in binding vector in sandbox:, compiling:(NO_SOURCE_FILE:0:0)"\n :at [clojure.lang.Compiler macroexpand1 "Compiler.java" 6644]}\n {:type java.lang.IllegalArgumentExce...

23:39 justin_smith: err

23:39 clojurebot: I don't understand.

23:40 justin_smith: ,(apply concat (for [a [{:a [0 1]} {:a [:b :c]}]] (:a a)))

23:40 clojurebot: (0 1 :b :c)

23:40 justin_smith: (mapcat :a [{:a [0 1]} {:a [:a :b]}])

23:40 ,(mapcat :a [{:a [0 1]} {:a [:a :b]}])

23:40 clojurebot: (0 1 :a :b)

23:40 dumptruckman: wait

23:40 apply concat?

23:40 justin_smith: mapcat is likely the one you want

23:40 dumptruckman: i see

23:41 justin_smith: but apply concat works too

23:41 mapcat is just apply concat map ...

23:41 $source mapcat

23:41 lazybot: mapcat is http://is.gd/HgriSd

23:41 dumptruckman: i see

23:45 when i'm defining a map is it possible to refer to the values i've defined ahead of another?

23:46 justin_smith: sounds like something where a let block plus a few calls to assoc would help

23:46 TEttinger: dumptruckman: you can use ##(declare)

23:46 lazybot: ⇒ nil

23:46 TEttinger: dumptruckman: you can use ##(doc declare)

23:46 lazybot: ⇒ "Macro ([& names]); defs the supplied var names with no bindings, useful for making forward declarations."

23:46 dumptruckman: O.o

23:46 for instance

23:46 TEttinger: ,(declare foo)

23:46 clojurebot: #'sandbox/foo

23:47 TEttinger: ,{:bar foo :a 1}

23:47 clojurebot: {:bar #object[clojure.lang.Var$Unbound 0x7c02c5a4 "Unbound: #'sandbox/foo"], :a 1}

23:47 TEttinger: ,(def mapperz {:bar foo :a 1})

23:47 clojurebot: #'sandbox/mapperz

23:47 TEttinger: ,(def foo "yay")

23:47 clojurebot: #'sandbox/foo

23:47 TEttinger: ,mapperz

23:47 clojurebot: {:bar #object[clojure.lang.Var$Unbound 0x7c02c5a4 "Unbound: #'sandbox/foo"], :a 1}

23:47 TEttinger: hm

23:47 dumptruckman: {:a a :b b :c :a} where the value for c is the value for :a

23:47 TEttinger: oh

23:47 justin_smith: yeah, use assoc for that

23:48 ,((fn [m] (assoc m :c (:a m))) {:a 0})

23:48 clojurebot: {:a 0, :c 0}

23:49 dumptruckman: meh

23:49 i think that's probably more complicated than juts putting the value again

23:49 justin_smith: dumptruckman: if you already knew the value, do that

23:49 TEttinger: or you could have it be a key into a different table

23:49 justin_smith: I thought you were talking about a situation where the caller could specify any :a they please, and you need to map :c to that too

23:50 dumptruckman: nah

23:50 i'm defining a player object which has a color key

23:50 and also needs to define a shape in the same map using that color

23:50 it might be useful later

23:50 when i get to having more than 1 player

23:50 TEttinger: ,(let [inner {:a 10 :b 20} outer {:a :a :b :b :c :a}] (inner (outer :c)))

23:50 clojurebot: 10

23:51 dumptruckman: wat

23:54 i can't wrap my mind around that

23:56 hmm

23:56 this doesn't seem to be doing what i'm going for

23:56 (apply concat (for [player (:players entities)] (:segments player)))

23:57 justin_smith: dumptruckman: equivalent is (mapcat :segments (:players entities))

23:57 and I think that version is a bit nicer

23:57 dumptruckman: well

23:57 it produces an empty lits

23:57 but there's definitely something in the segments part that i'm trying to retrieve

23:58 so entities is a map that has a seq of :players and each element of that seq has a seq of :segments

23:59 justin_smith: so (-> entities :players first :segments) will always give you a seq

23:59 if so, that for comprehension should work

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