#clojure – 2015-01-10

2015-01-10

01:29	dagda1_	if I have a vector like this [:a :b] can I add metadata to each element?
01:51	luxbock	dagda1_: keywords can't have meta data
02:12	DomKM	Anyone have a good workflow for autotesting cljx namespaces on compile?
05:48	cfleming	$mail andyf Here are the changes you were asking about the other day: https://github.com/cursiveclojure/riddley/blob/master/src/cursive/riddley.clj. I use metadata to mark interesting parts of the form: I always expand the whole top-level form, ::top-form is the form actually selected by the user, i.e. the one I actually display to them. When requesting an expansion I tag an element in the form with ::expand-to, and only the path from the root to
05:48	lazybot	Message saved.
05:48	cfleming	that form is expanded. Forms which are actually expanded are marked with ::expanded so I can mark them in the IDE.
05:48	cfleming	$mail andyf <cut off> that form is expanded. Forms which are actually expanded are marked with ::expanded so I can mark them in the IDE.
05:48	lazybot	Message saved.
06:22	hellofunk	cemerick or anyone: does Austin or Piggieback rely on websockets or ajax (xhr) for its magic?
06:45	andyf	cfleming: Thanks for the link
06:46	cfleming	andyf: No problem, let me know if you have more questions
06:47	cfleming	hellofunk: My knowledge of this isn't perfect, but I believe that Piggieback doesn't provide a transport, that's a layer bridging nREPL to a CLJS REPL. Austin is an ajax transport on top of Piggieback, Weasel is a websocket one
07:31	Biofobico	can anyone please explain me what reduce does? (reduce + [1 2 3 4 ])
07:33	tikotus	1+2+3+4
07:33	tikotus	,(reduce + [1 2 3 4])
07:33	clojurebot	10
07:36	Biofobico	so it's usage is to sum what is inside the '[' ?
07:40	tikotus	No, it sums them because you give it + as the function. It applies the given function for the two first values, then applies the function for the result and the third value. Then it applie the function for the result and the fourt value.
07:41	tikotus	The function can be any function that takes 2 parameters
07:41	PeakCode	So the example can be seen as (+ (+ (+ 1 2) 3) 4)
07:44	Biofobico	so its a more condensed version of what PeakCode wrote?
07:47	mearnsh	,(reduce #(if (even? %2) (conj %1 %2) %1) [] (range 10))
07:47	clojurebot	[0 2 4 6 8]
07:47	mearnsh	hm
07:47	PeakCode	Well, you wouldn't usually have a literal as collection, but a collection you got from somewhere.
07:48	Biofobico	tried (+ [1 2 3 4]) which gave me an error
07:48	PeakCode	,(apply + [1 2 3 4])
07:48	clojurebot	10
07:50	Biofobico	thank you
07:51	Biofobico	im learning clojure (never programmed before) so excuse my noob questions please :P
07:55	PeakCode	NP. https://clojuredocs.org/ is a great resource with many code examples. See for example https://clojuredocs.org/clojure.core/reduce.
08:02	soro	What is a good book it to start with clojure?
08:02	kungi	soro: I liked Clojure in Action
08:02	kungi	soro: But there are many others. Have a look at this Stackoverflow: https://stackoverflow.com/questions/2544043/clojure-learning-resources
08:02	triss	I've got a seq of seq's - whats the simplest way of getting this as a vector of vectors?
08:04	Duke-	(mapv vec seq-of-seqs)
08:04	Biofobico	PeakCode: Thank you. Will check it out because this reduce thing hurts my little brain :)
08:04	PeakCode	:-)
08:06	kungi	Duke-: I thought about mapv vector but got this while trying [[(1 2 3)] [(1 2 3)]]
08:06	Duke-	there's a difference between vector and vec
08:06	kungi	Duke-: I see that now :-)
08:06	triss	ah cheers Duke-!
08:06	triss	of course
08:06	kungi	Biofobico: Your brain will grow in time to adjust to reduce and the like.
08:08	Biofobico	:)
08:14	Biofobico	im finding that reduce is a strange word for which it does
08:16	mi6x3m	Biofobico: what would be a better one?
08:19	kungi	Biofobico: It is also called fold in some contexts
08:21	Biofobico	I think since im not a programmer, i can't seem to find an use for it
08:22	kungi	Biofobico: then think about it that way. Reduce reduces a collection to one value. That's how it makes sense.
08:24	Biofobico	kungi: can't thank you enough. You just gave me an ah-ah moment
08:24	kungi	Biofobico: :-) Always happy to help
08:25	hipsterslapfight	that value can also be a collection of course :v
08:25	hipsterslapfight	reduce is <3
08:25	Biofobico	so (reduce [ 1 2 3 4 5] (6 7 8 9)) is somewhat valid?
08:25	Biofobico	im sure that code is wrong
08:26	Biofobico	but for the sake of simplicity it will make something like (1 2 3 4 5 6 7 8 9)?
08:27	kungi	Biofobico: that's what ,(reduce conj [1 2 3] [4 5 6] [7 8 9]) does
08:27	kungi	conj = conjoin
08:28	kungi	,(reduce conj [1 2 3] [4 5 6] [7 8 9])
08:28	clojurebot	#<ArityException clojure.lang.ArityException: Wrong number of args (4) passed to: core/reduce>
08:28	kungi	,(reduce conj '([1 2 3] [4 5 6] [7 8 9]))
08:28	clojurebot	[1 2 3 [4 5 6] [7 8 9]]
08:31	Biofobico	Again, can't thank you guys enough :)
08:32	Biofobico	(reduce into [[1 2 3] [:a :b :c] '([4 5] 6)]) [1 2 3 :a :b :c [4 5] 6]
08:32	Biofobico	makes perfect sense now
08:36	hellofunk	can anyone explain to me what happens in a server environment when you a browser sends an ajax request to Ring and then sends another while the first is still processing, is this synchronous on the server side? i.e. the first request must complete before the second is processed by the server?
08:38	PeakCode	No, they should be processed in parallel.
08:38	hellofunk	PeakCode: that is the default behavior from the Ring server, to multithread ajax requests?
08:40	PeakCode	Yes. Are you experiencing something else?
08:40	hellofunk	PeakCode: no i haven't taken a deep look, but it made me think while I try to figure out the best approach to a problem
08:41	PeakCode	OK.
09:39	AeroNotix	was playing with some ideas to more declaratively express agents: https://gist.github.com/2a7cb69f29a4d109447f
09:42	imanc	if I try this in the repl: (1 2 3 ~(inc 4)) i get : (1 2 3 (clojure.core/unquote (inc 4))) whereas I see examples online where this is evaluated to (1 2 3 5)
09:43	imanc	err, that original statement should be quoted: '(1 2 3 ~(inc 4))
09:44	mearnsh	&`(1 2 3 ~(inc 4))
09:44	lazybot	⇒ (1 2 3 5)
09:44	mearnsh	notice ` vs ', syntax quote vs quote
09:44	imanc	oh quote vs backtic..
09:45	mearnsh	you generally use unquote inside syntax quotes
09:46	imanc	OK thanks - I missed that there was a difference between quotes and syntax-quotes
10:19	gfredericks	semisort-key: https://www.refheap.com/95939
10:20	gfredericks	^ can use that to semishuffle an infinite collection too
10:45	OscarZ	are macros just compile-time magic? they will be just normal functions runtime?
10:50	gfredericks	OscarZ: under normal usage the macros don't really exist at runtime
10:51	gfredericks	OscarZ: e.g., at runtime (f x) is indistinguishable from (-> x (f))
10:51	OscarZ	ok..
10:51	OscarZ	i somehow got this crazy idea that macros do some crazy bytecode manipulation stuff with the arguments at runtime when they are actually called
10:52	gfredericks	not remotely
10:52	gfredericks	they're a lot simpler than that :)
10:52	gfredericks	they just transform the code (not bytecode) at compile-time
10:52	OscarZ	what are the typical use cases for macros? what do people usually run into first that you need macros for?
10:53	OscarZ	yes, ok
10:53	gfredericks	well the first reason to learn about macros as a beginner is because you're using them all the time
10:53	gfredericks	from clojure.core and libraries
10:54	OscarZ	i guess when-not is a macro? its not obvious to me why its not a normal function..
10:54	gfredericks	conditionals like when-not want to do delayed evaluation
10:55	gfredericks	if when-not were a function, the code that you're trying to conditionally execute would get executed before when-not was even called
10:55	gfredericks	if that doesn't make sense, just try writing when-not as a function and see what happens :)
10:56	OscarZ	oh right.. its called call-by-name or something when arguments are evaluated before calling a function ?
10:56	OscarZ	like in java etc..
10:57	gfredericks	I haven't heard that; but I don't know what to call it; strict evaluation perhaps
10:57	OscarZ	yes thats it
10:57	OscarZ	i think haskell is not like that.. ran into it somewhere
10:58	gfredericks	right haskell is the primary counterexample
10:58	gfredericks	or...nonexample
10:59	OscarZ	is "if" normal function?
10:59	gfredericks	no, there are a handful of primitives called "special forms" -- if is one of them
10:59	gfredericks	but if it weren't, it would be a macro instead of a function for the same reason as when-not
11:00	OscarZ	but is "if" special for the very reason that it only evaluates the branch that is required?
11:01	gfredericks	when-not does that too
11:01	gfredericks	but when-not does it by generating code that uses if
11:01	gfredericks	i.e., when-not is written in terms of if
11:01	gfredericks	you have to have some base thing to rewrite to
11:01	gfredericks	and that base thing is if
11:02	gfredericks	which is implemented in the compiler
11:02	gfredericks	with the other special forms, like fn, loop, let
11:02	OscarZ	oh right.. somehow i thought when-not = if-not .. but its different :)
11:05	gfredericks	OscarZ: http://www.infoq.com/presentations/macros-clojure-west-2013
11:05	OscarZ	hey its by you.. ill check it out :)
11:08	OscarZ	i guess this doesnt work? (defn when-not [test code] (if (not test) (do code) nil)
11:09	gfredericks	~tias
11:09	clojurebot	tias is try it and see
11:09	OscarZ	ok
11:12	OscarZ	fail :) ok.. it works if i use it like (when-not false 15) .. but i'd like to have some code in there.. not just a value
11:13	gfredericks	right
11:14	OscarZ	so it takes a body of code, thats why i need to use a macro.. its a bit like passing a function but its inline or something.. its a bit weird compared to what im used to
11:16	OscarZ	like in java.. its a call like whenNot(false, new Function() { ... }); ...hmm maybe i shouldnt follow this line of thought :(
11:17	OscarZ	but yeah, i think i understand it a little better .. going to watch the video now
11:19	gfredericks	OscarZ: yeah you can get the same behavior by using functions -- it's just more verbose
11:19	gfredericks	macros are mostly about getting new syntax
11:20	OscarZ	yes, i can understand it better now that clojure is a bit special.. when-not looks just like normal function call but you are actually passing in a block of code
11:21	gfredericks	by "using functions" I mean using higher-order functions to delay evaluation like you just showed, not "using a function instead of a macro" like we were discussing earlier
11:22	OscarZ	ok
11:24	OscarZ	what if you did something (when-not false '(some-code-block)) .. can you pass in a block of code like that ?
11:25	OscarZ	im not sure if i completely understand what ' does.. at least it doesnt call it right away
11:25	gfredericks	you can do it but the only way to "execute" the code is manually by calling eval, which is problematic in a few ways
11:25	gfredericks	at that point you're just doing macros yourself instead of using the built-in feature
11:27	OscarZ	ok.. cool
11:27	OscarZ	yes its much more clean that way
11:28	gfredericks	I think there's a few minutes in the talk on exactly that approach though
11:28	OscarZ	watching now
11:51	emaczen	can someone tell me how to user cider to get a repl connected to the remote server?
11:53	csd_	How can I use sort-by with `for`? I'm not sure how to package what for returns into a collection for sort-by.
12:01	csd_	Oh I see the problem--I'd had sort-by within the `for`.
12:12	hellofunk	is anyone familiar with the book Principles of Concurrent and Distributed Programming?
12:13	hellofunk	by Ben-Ari
12:37	OscarZ	gfredericks, cool presentation, thanks! it made me understand the homoiconicity thing a little better.. didnt really understand whats going on
12:48	Atarian	Anybody got time to answer a stupid question from a procedural programmer?
12:49	hellofunk	,~question
12:49	andyf	~anyone
12:49	clojurebot	Just a heads up, you're more likely to get some help if you ask the question you really want the answer to, instead of "does anyone ..."
12:49	clojurebot	#<CompilerException java.lang.RuntimeException: Unable to resolve symbol: question in this context, compiling:(NO_SOURCE_PATH:0:0)>
12:50	hellofunk	lol whoops
12:50	Atarian	heheheh
12:50	Atarian	Righto. So I understand why immutable objects are better than mutable ones, threadsafe &c
12:51	Atarian	But in procedural programming, Im used to making a struct to hold data, then modifying it. All my functions know where it is...
12:51	chouser	that's called global state
12:51	Atarian	In Clojure, if I am right, modifying a data structure returns a new structure
12:52	chouser	that's right
12:52	andyf	Actually, if anyone has any specific benefits to immutable data that they can explain in a way that programmers who have not used them before could ?get?, I?d love to hear them. I don?t know how to explain it well yet, other than something like ?it gives you a lot of new invariants you can be sure of vs. when using mutable data?. What I mean are: benefits even in a single-threaded program.
12:53	Atarian	So how do I deal with the new structure? Where do I (for lack of a better way of putting it) keep it where all of my functions can get to it?
12:53	hellofunk	Atarian: andyf: notable benefit: new data structure, yes, but the shared structure of similar data structures means that it is not constructed from scratch, therefore is highly efficient compared to mutable data structures
12:53	Atarian	I'm not knocking Clojure btw, I just think if I understand this I'll have that lightbulb moment
12:53	andyf	Atarian: In many cases, it is passed on to the next function or step of the code without needing to keep it anywhere.
12:53	chouser	Atarian: Clojure comes with some reference types that mutate, holding subsequent versions of immutable values.
12:54	andyf	But yes, when you do need to keep it somewhere that is stateful, most people use an atom in Clojure to store values that change over time.
12:54	andyf	but sparingly.
12:54	Atarian	Andyf: chouser: Right, OK... so I return the unnamed, modified structure to the next function down the line
12:55	chouser	Though you should be aware that coming from a procedural background, you're going to rely on those reference types more often than you will once you're more familiar with functional-style programming.
12:55	andyf	hellofunk: That is a reason that immutable data structures are much more efficient than the simple way of implementing them. That is good, but I'm looking for benefits in how you can think about your program, not how fast they run.
12:55	emaczen	How can I connect/start a remote REPL?
12:55	chouser	Atarian: well, there's that approach as well, passing immutable values down along the line. That's actually closer to "functional style"
12:56	Atarian	emacsen: C-c M-J
12:56	chouser	Atarian: an approach more familiar to you, that you'll use less often later, would be (def my-global-state (atom 42)) ...and then you can (swap! my-global-state inc) for example to change it, and @my-global-state to get the current value
12:56	Atarian	C-c M-j even
12:57	hellofunk	andyf: i think that counting on that performance benefit means you can do things with data sharing and passing data around, mutating it, making "copies" are all valid options you may not considern in environments where they are expensive.
12:57	Atarian	chouser: brain is taking a little to catch up if I go a bit quiet lol
12:58	andyf	hellofunk: I am all for structural sharing, no question about it. What I'm looking for is, given that it can be made efficient, why do people who have used them for a while like them so much?
12:59	andyf	What advantages do they give you, when you use them most of the time, that you could explain to someone who has never written programs in that style?
13:00	emaczen	Atarian: That started a local server
13:00	hellofunk	andyf: for me a lot of it has to do with not having to think about or worry about the performance hit with passing around large data or making copies of it with small changes. i'd have not done that in an environment without structural sharing becauase of the performance penalties
13:00	Atarian	Keep waiting
13:00	andyf	I suppose one of the biggest ones is that in programs where mutability is the norm, even single-threaded programs, it requires careful documentation and/or following conventions to know what parts of a big data structure any given function can mutate, and that can be difficult to keep track of mentally.
13:00	chouser	Atarian: these are exactly the questions to ponder. Answering them to my own satisfaction is exactly what I had to do to become confidant as a functional programmer.
13:00	Atarian	emacsen: or lein repl from the command line
13:01	emaczen	Atarian: I've tried lein repl :connect http://ip:port/repl
13:01	Atarian	chouser: I'm trying to understand atoms - You can swap! a map/list/other type into it, and use it like a variable name to access it from other places?
13:03	andyf	Atarian: reset! on an atom is nearly the same as assigning a value to a global variable. swap! is an atomic "read the current value, use this function to calculate its next value, and assign it that value"
13:03	Atarian	emacsen: I honestly just use C-c M-j from emacs or lein repl from bash, no magic
13:04	emaczen	Atarian: How does it know to connect to a remote host as opposed to localhost?
13:04	andyf	but many people use swap! on atoms even in single-threaded Clojure programs, since the next value they want is a function of the current value, e.g. conj a new value to the end of a vector.
13:04	Atarian	Ooh, sorry I didn't know you were trying to connect to a remote server
13:04	Atarian	My bad
13:05	emaczen	Atarian: No worries
13:05	Atarian	Thanks for your thoughts chouser and andyf, I'm off to try and write a few functions to understand this better
13:07	hellofunk	does anyone know what the default is for Ring with it comes to throttling the number of simultaneous ajax requests (which i guess are just "requests" since the server doesn't know the difference)?
13:07	weavejes_	hellofunk: Ring itself doesn't throttle anything. Different adapters have different thread pool sizes, however.
13:08	hellofunk	weavejes_: by "adapter" what are you referring to?
13:08	hellofunk	weavejester: do you mean middleware handles that?
13:08	weavejester	hellofunk: A ring adapter is the thing that turns a handler into a HTTP server.
13:09	weavejester	The Ring Jetty adapter has a maximum thread pool size of 50.
13:09	hellofunk	is it safe to assume that all requrests that come into a Ring server are handled in parallel?
13:09	weavejester	hellofunk: Yes... depending on the adapter.
13:10	weavejester	I believe httpkit has only 4 threads by default.
13:11	hellofunk	weavejester: compojure.handler/api would be an example of an adapter?
13:11	weavejester	hellofunk: No
13:12	weavejester	hellofunk: That's just a function that pulls in some standard middleware
13:12	weavejester	(and incidentally is deprecated)
13:12	weavejester	ring.adapter.jetty/run-jetty is an example of an adapter.
13:12	hellofunk	weavejester: the shiny new chestnut lein template uses compojure.handler./api.
13:13	hellofunk	since run-jetty seems to be the default adapter in all the project tempaltes i've seen, this is one that handled all requests in parallel?
13:14	hellofunk	and if it has a thread pool size of 50, this would suggest that it handled at most 50 simultaneous requests, or can a single thread handle more than one request at once?
13:14	weavejester	hellofunk: compojure.handler/api has been deprecated for a little over 3 months now. They should probably change that.
13:14	hellofunk	weavejester: i will let them know
13:14	weavejester	hellofunk: All adapters I'm aware of handle requests in parallel.
13:15	weavejester	hellofunk: Even httpkit has a thread pool of 4.
13:15	weavejester	And yes, if it has a thread pool size of 50, it can handle at most 50 simultaneous requests.
13:15	weavejester	Each request is handled by a separate thread.
13:18	hellofunk	weavejester: this changelog seems to suggest the made the switch from your handler last month, but when I use the lein template, it still uses it: https://github.com/plexus/chestnut/blob/e0a1be042df633dd245af586476ef4fc899d3544/doc/CHANGELOG.md
13:19	weavejester	hellofunk: Yeah, looks like they've made the change, but haven't released it yet.
13:37	hellofunk	weavejester: what is a good lein tempalte i can look at now that shows the new defaults instead of compojure.handler?
13:40	weavejester	hellofunk: Hm... I'm not sure you need a template for that. You could just use the chestnut snapshot, though, if you're already familiar with that.
13:40	weavejester	hellofunk: lein new chestnut blah --snapshot
13:41	PeakCode	hellofunk: If you need your web server to be able to handle really many requests in parallel you should look for a server that can handle requests asynchronously, like http-kit or Pedestal.
13:45	hellofunk	PeakCode: how many requests would warrant a change to http-kit? are we talking dozens or thousands?
13:47	hellofunk	and it would seem to me that even if http-kit handles things asynchronously, ultmiately they'd get processed faster with jetty if it has over ten times the threads available
13:50	arohner	hellofunk: closer to thousands, IMO
13:50	arohner	hellofunk: threads start to slow down when threads >> CPU cores
13:50	PeakCode	hellofunk: Every thread consumes memory and brings overhead to the processing, but for a dozen simultaneous requests it matters little.
13:52	PeakCode	hellofunk: http-kit can handle thousands of simultaneous requests, but not with normal Ring handlers.
13:52	Chaze	#scala
13:53	PeakCode	hellofunk: The async processing detaches the thread from the request and therefore it can suffice with just four threads.
13:53	weavejester	Asynchronously processing requests means that you're not wasting threads on blocking I/O processes.
13:54	hellofunk	can anyone point me to an example of a setup with http-kit that would be ready for thousands of requests? what Ring handlers would you use?
13:55	weavejester	hellofunk: You'd need to structure your application a little differently.
13:55	weavejester	Well, normal Ring can handle thousands of requests.
13:56	weavejester	Async doesn't give you more CPU
13:56	weavejester	It just means there's less wasting of resources waiting for I/O
13:57	weavejester	A Java process can have a thousand threads without too much problem.
13:57	weavejester	But tens or hundreds of thousands of threads becomes a problem.
13:58	weavejester	Async is useful for apps that are heavy on I/O and open connections like websockets.
13:58	hellofunk	ok, interesting. my needs are not there at this point so i don't think it warrants time to research http-kit more.
13:59	Atarian	Anyone see what's wrong with this? getVals returns a map:
13:59	Atarian	(def character (atom {}))
13:59	Atarian	(reset! character getVals)
13:59	Atarian	(print (character :name)))
13:59	weavejester	Is getVals a function?
13:59	Atarian	Yep
13:59	Atarian	This is the error
14:00	Atarian	ClassCastException clojure.lang.Atom cannot be cast to clojure.lang.IFn dungeonworld.core/-main (core.clj:30)
14:01	andyf	Function calls must have parens around them, e.g. (getVals) if there are no arguments.
14:01	Atarian	OK cheers, I'll try that - and no, no args
14:02	andyf	otherwise your reset! call above sets the value of the character atom to the value of the function itself.
14:02	PeakCode	weavejester: Has there been any progress lately regarding async processing in Ring?
14:02	andyf	not the value returned when calling the function.
14:03	Atarian	(reset! character (getVals))
14:03	Atarian	doesnt work either, still get the cast error
14:03	andyf	also, to get the current value of an atom, you must use (deref character), or the shorthand form @character
14:04	weavejester	PeakCode: What do you mean?
14:04	andyf	e.g. (print (@character :name))
14:04	Atarian	Still not quite as bad as pointers hehe
14:05	PeakCode	weavejester: IIRC there is a GitHub issue regarding this?
14:05	weavejester	PeakCode: Not that I can see.
14:08	Atarian	Thanks Andyf: And yes, I just had a moment of enlightenment when you explained how the parenthesis assigns the result not the fn
14:10	PeakCode	weavejester: Sorry, I thought of https://github.com/clojure-liberator/liberator/issues/91 for Liberator.
14:10	andyf	Atarian: cool. Yeah, functions are values, and they can be passed as arguments, or returned as values from function calls. You can save them in data structures, if you wish, e.g. as values in a map. Calling a function is often done as (function arg1 arg2 ...), but there are many other ways, e.g. (map function collection)
14:11	Atarian	This is where my hardcoded C brain is going to have a bit of trouble, cheers
14:11	andyf	It is a bit like C function pointers
14:11	andyf	but there are several differences
14:14	weavejester	PeakCode: I had been considering async approaches for Ring, and the subject has come up a few times in the past, but so far I haven't had a need to do so.
14:23	hellofunk	i'm seeking recommendations on books or great resources to help train my brain program-wide asynchronous architecture. there is the Ben-Ari book i've heard about, any other advice? I'm very curious about strategies that go beyond all the use cases I've had till now, which mainly involve UI handling and callback management
14:31	PeakCode	weavejester: Is there any specific reason for the ring-jetty-adapter to still use Jetty 7?
14:33	PeakCode	weavejester: Ignore. Just found https://github.com/ring-clojure/ring/issues/177.
14:34	hellofunk	interesting quote: " computerized systems in modern cars have half a million lines of
14:34	hellofunk	code, and that electronics account for 25% of their cost and this percentage is
14:34	hellofunk	forecast to increase"
14:34	hellofunk	sorry about that multiline paste
14:35	mavbozo	hellofunk: from which article/writing?
14:36	hellofunk	mavbozo: from a book by Ben-Ari about concurrency
14:36	hellofunk	mavbozo: Principles of the Spin Model Checker
14:37	hellofunk	though i think he more well-known for his other book about general concurrency architecture
14:47	mavbozo	hellofunk: interesting. added that book to my reading list.
14:49	hellofunk	weavejester: PeakCode: I am rather curious what happens when two different Ring requests simultaneously attempt to mutate a common global value. since the parallelization is implicity, how would the system handle this? is it safe?
14:49	weavejester	hellofunk: Clojure refs, atoms and agents are designed to be used concurrently.
14:50	weavejester	hellofunk: Atoms and refs are always updated atomically.
14:50	hellofunk	weavejester: ok, the fact that the mutations are caused by a Ring request is actually trival in this case
14:50	weavejester	hellofunk: Right, it's the same as any multi-threaded program.
15:17	arrdem	anyone aware of packages using mvn qualifiers other than -alpha-<n>?
15:17	Biofobico	is there a best practice for this: (:b my-keyword) or (my-keyword :b)
15:18	arrdem	Biofobico: both of those are a type error...
15:18	arrdem	&(:foo :bar)
15:18	lazybot	⇒ nil
15:18	arrdem	okay. meaningless. not an error.
15:19	Biofobico	:P
15:19	mavbozo	&(:P :P)
15:19	lazybot	⇒ nil
15:20	arrdem	Biofobico: if you have a constant keyword, it's idiomatic to use it in the function call position rather than using the target lookup structure in the function call position.
15:21	arrdem	Biofobico: IMO using lookup structures as functions directly should be avoided for uses of (get) which does the same thing and is somewhat more explicit.
15:25	Biofobico	arrdem: didn't understand half of what you wrote. I'm learning clojure by following a tut and testing "oposite ways" to see what happens
15:25	justin_smith	arrdem: I think that nil-returning behavior of get on non-lookup entities is responsible for X% of Clojure's "wait why did it blow up there?" phenomenon
15:26	arrdem	justin_smith: agreed, however It's A Feature™
15:26	justin_smith	Biofobico: get is like the dude, get doesn't care if you can actually get anything from the argument, it's all like "shurg, have a nil"
15:26	justin_smith	,(get get get get)
15:26	clojurebot	#<core$get clojure.core$get@75ccf88d>
15:26	arrdem	bahahaha
15:26	arrdem	(inc justin_smith)
15:26	lazybot	⇒ 167
15:27	mavbozo	(inc justin_smith)
15:27	lazybot	⇒ 168
15:27	arrdem	Biofobico: does justin_smith's code snippet there make sense?
15:28	dnolen_	Om 0.8.0 is out, new way to include the dependency [org.om/om "0.8.0"] have fun!
15:28	rhg135	Useful obfuscation technique
15:29	Biofobico	arrdem: tested and it returns nil
15:29	arrdem	$grim clojure.core/get
15:29	lazybot	http://grimoire.arrdem.com/1.6.0/clojure.core/get
15:29	arrdem	need to patch that...
15:29	Biofobico	clojure is my 1st programming language so bear with me please :)
15:30	arrdem	ofc
15:31	jaen	Hello, I'm trying to set up code reloading with http-kit by following something I did a long time ago and which actually worked, but for some reason it's not working when I'm doing the same thing in the new project. When I copy the ring reload middleware verbatim and sprinkle it with some debugging printlns it seems as if it recognizes some changed namespaces, but `(require ns-sym :reload)` somehow fails to
15:31	jaen	reload the namespace. Any hints where/how I can start debugging this?
15:31	Biofobico	get makes sense now after reading about it
15:32	arrdem	get is pretty straightforwards.
15:33	Biofobico	im founding the language pretty clear so far
15:34	hellofunk	justin_smith: i do not get your list of four gets
15:34	Biofobico	only issue i'm having, is writing the code "from the inside out"
15:34	justin_smith	,(get [] :some-key :default)
15:34	clojurebot	:default
15:34	justin_smith	hellofunk: ^ does that help?
15:34	hellofunk	justin_smith: ah yes
15:34	hellofunk	it returned the function get itself, of course
15:35	justin_smith	hellofunk: indeed, and any instance of "get" in your code can thus be replaced with (get get get get) (certain macros excluded, of course)
15:35	arrdem	(dec justin_smith)
15:35	lazybot	⇒ 167
15:36	hellofunk	lol
15:36	hellofunk	,((get get get get) [1 2] 1)
15:36	clojurebot	2
15:39	andyf	huh, new function 'random-sample' comin in 1.7.0. Seems more specialized than a lot of things in clojure.core
15:40	justin_smith	andyf: what is it exactly?
15:40	andyf	filter with a specified probability of keeping each element in a given collection
15:40	arrdem	that's... oddly specific indeed
15:40	andyf	sounds like something generative testing would use, but yeah, weird.
15:41	justin_smith	as in ##(filter (fn [_] (< (rand) 0.5)) (range 10)) ?
15:41	lazybot	⇒ (2 3 6 7 8 9)
15:42	andyf	https://github.com/clojure/clojure/blob/master/src/clj/clojure/core.clj#L7325
15:42	justin_smith	I must be psychic!
15:42	andyf	or my verbal description was spot on :)
15:42	justin_smith	indeed
15:43	andyf	Yeah, all the transducer stuff I knew about, but that one escaped my notice until today when I was looking at all of the new Vars added to clojure.core since 1.6.0
15:46	andyf	Complete list of new public Vars in clojure.core from 1.6.0 to 1.7.0-alpha5, for the curious: ->Eduction cat completing dedupe eduction ensure-reduced random-sample run! transduce unreduced update volatile! volatile? vreset! vswap!
15:49	andyf	justin_smith: Ooh, the 4 gets thing goes on my list of obfuscated Clojure tricks
16:02	andyf	Not much in my collection yet: https://github.com/jafingerhut/jafingerhut.github.com/blob/master/notes/obfuscated_clojure.clj Oddly enough justin_smith is highly represented :)
16:04	mavbozo	(inc andyf)
16:04	lazybot	⇒ 22
16:10	arrdem	Thoughts on trying to stretch Grimoire to support the host languages of Clojure dialects? Eg. add Java docs for Clojure, JS for CLJS, .net for CLJCLR
16:10	arrdem	seems like it adds a lot of potential pain
16:12	andyf	At least for Java, I've found the existing Java API docs hosted by Oracle to be very Google-able, and inter-class/method/etc. links are often good.
16:12	arrdem	yeah I don't think there's a lot of room to win there, the idea was just that Clojure artifacts may sometimes contain Java classes as well and that it could be worthwhile to document both.
16:13	arrdem	Obviously I'm not gonna compete successfully with Oracle for java.lang docs :P
16:13	andyf	oh, you mean add part or all of the underlying Java implementation of Clojure/JVM to Grimoire?
16:13	arrdem	yeah
16:14	arrdem	I'm restructuring the schema Grimoire uses so that ClojureScript can be supported properly and I'm taking the opportunity to ponder other possible changes as long as I'm making another round of breaking ones.
16:14	andyf	The audience seems like it would be limited to those wanting to modify Clojure, or add new custom data structures.
16:16	hellofunk	andyf am i confusing you with someone else, or do you have a blog post somewhere about programming chess moves?
16:16	andyf	hellofunk: Not me
16:17	andyf	Unless you mean some emails to the Clojure Google group about a performance problem involving the old Clojure hash function, which came to light because of an N-queens benchmark someone wrote.
16:18	hellofunk	no, something else i ran across a couple days ago but can't remember where i saw it
16:35	jaen	Hmm. I think I figured out my issue - the original code closed over `handlers` top level `def` directly while the new code used bidi's new option to specify a handler-resolving function and it closed over the def in the function that called it. In the former case namespace relaod changed the handlers, in the latter it did not.
16:35	jaen	Is there some subtle Clojure behaviour I'm missing here?
16:39	mrdiesel_	hi , i build my first program in C but i have this error message 'Process terminated with status 255 (0 minute(s), 0 second(s))'
16:39	arrdem	mrdiesel_: wrong channel
16:40	mrdiesel_	ok sorry
16:40	arrdem	jaen: paste code and/or error please that's not enough for us to help you with.
16:40	andyf	Not sure if I know exactly what you mean, but sometimes people use explicit Vars in their code, which adds another level of indirection at function call time, but it handles some reload cases more dynamically, e.g. call #'namespace/fn-name instead of fn-name
16:40	jaen	arrdem: that's basically it - https://gist.github.com/jaen/1e69cf7ec23adb350351
16:41	jaen	Just differs in how the top level def is closed over.
16:42	Glenjamin	jaen: defs aren't closed over
16:42	Glenjamin	well, sort of
16:42	jaen	Yeah, I noticed sort of
16:42	Glenjamin	when you refer to something that is def'd, you get a reference to the var
16:43	Glenjamin	and then the var is derefed when that function is called
16:43	mrdiesel_	this is the program 'include <stdio.h>
16:43	mrdiesel_	main()
16:43	mrdiesel_	{
16:43	mrdiesel_	printf("hello world");
16:43	mrdiesel_	}
16:43	mrdiesel_	'
16:43	Glenjamin	giving the effect of late-binding
16:43	andyf	mrdiesel_: still wrong channel
16:43	Glenjamin	function arguments are not late-bound, so you're dereffing the var in make-handler
16:43	jaen	Also no one likes pasting code into the channel, use gist or pastebin or somesuch
16:43	jaen	Glenjamin: I see
16:44	mrdiesel_	ohhhhhh sorry again
16:45	arrdem	,1
16:45	clojurebot	eval service is offline
16:45	arohner	While trying to 'lein ring war', I'm getting "Exception in thread "main" java.lang.Exception: Found lib name 'foo.system' containing period with prefix 'foo.main'. lib names inside prefix lists must not contain periods". Any ideas?
16:46	arrdem	arohner: sounds like your NS form somewhere is hosed
16:46	arohner	arrdem: yeah, that's what google seems to say, but `lein uberjar` works just fine for me
16:46	arrdem	arohner: trying to do (:require [a.b [c.d :as ..]]) is the only way I know to get that error.
16:46	weavejester	arohner: Perhaps the :ring settings are wrong? A bad symbol name, perhaps?
16:47	arrdem	arohner: I'm gonna guess that you're not AOTing something that's in error so the illegal ns form slides through but that's just a guess.
16:48	arohner	AFAICT, I'm AOT'ing every file
16:48	arohner	which leads me to think weavejester's :ring theory is interesting
16:48	weavejester	lein-ring does generate namespaces for the servlet
16:49	weavejester	So if the symbols it's using are wrong, that generated code might be triggering the error.
16:49	arohner	weavejester: do :init and :handler have to be in the same ns?
16:49	weavejester	arohner: They shouldn't need to be.
16:50	weavejester	arohner: Which version of Lein-Ring are you using, btw?
16:50	arohner	0.9.0
16:50	arohner	is :handler a fn of no args, or a var?
16:51	weavejester	Hm. The war-generating code has been changed a little between 0.8.13 and 0.9.0. It's possible you're hitting a bug that wasn't found in testing
16:51	arohner	*value
16:51	weavejester	:handler is a symbol to a var
16:51	jaen	Glenjamin: so then what should I do? Copypasting bidi's `make-handler` function just to be able to close over a `def` doesn't strike me as the greatest idea ever : \|
16:51	arohner	ok, with no :init, it just compiled the war. I'll try to repro again
16:51	weavejester	arohner: You could try downgrading to 0.8.13, to see if the problem is the new code.
16:52	arohner	weavejester: k, I'll try that once this compile finishes
16:52	Glenjamin	jaen: we'd need to see more code to provide context
16:52	Glenjamin	from the example you gave, its unclear why you wouldn't just use the first one
16:53	arohner	weavejester: {:init foo.main/-main, :handler foo.system/ring-handler} works fine in 0.8.13, not in 0.9.0
16:54	arohner	commenting out :init makes 0.9.0 compile
16:54	arohner	`lein ring war` in both cases
16:54	jaen	Because I think libraries are here to have their functions called instead of copied&pasted. The first code has a verbatim copy of bidi's ring handler making function. I would like to be able to just call it.
16:55	weavejester	arohner: Could you open an issue for it?
16:55	arohner	sure
16:58	jaen	Glenjamin: but I think I relised what's the solution - calling the function wwith #'handlers should provide the desired result, yes?
16:58	jaen	And it seems it works.
16:58	jaen	Thanks for pointing me in the right direction.
17:15	espinho	is it possible to have automatic real time eval in emacs like the live repl feature in lighttable?
17:18	hellofunk	espinho: just about anything is possible in emacs but i don't know of anything like that having been developed. it just takes someone to sit down and write it. i doubt it will happen.
17:18	dnolen_	http://localhost:4000/2015/01/10/faster-validation-through-immutability/
17:19	dnolen_	oops http://swannodette.github.io/2015/01/10/faster-validation-through-immutability/
17:21	espinho	hellofunk: Thank you
17:27	AWizzArd	dnolen_: looks like an interesting read
17:27	dagda1_	If I have a function that returns a lazy seq like this https://gist.github.com/dagda1/d99bf42f31e99ae3b07c can I loop...recur lazily?
17:28	arohner	weavejester: I have a running beanstalk instance on 0.8.13, thanks
17:28	arohner	when I SSH into the box, I see 'There are 20 security update(s) out of 70 total update(s) available'. Thought EB handled that for you?
17:28	arohner	do I need to specify a more recent AMI?
17:28	AWizzArd	dagda1_: You won’t have to use recur, you can call the function by name directly and have it return a lazy concatenation via lazy-cat
17:31	dagda1_	AWizzArd: thanks, I have not heard of lazy-cat, I"ll check that out
17:32	rhg135	dnolen_, am i correct in thinking it's basically a tagging system?
17:32	justin_smith	dagda1_: why not next instead of (seq (rest ...))
17:33	dagda1_	justin_smith: I'm not entirely sure what the difff is between rest and next
17:33	dnolen_	rhg135: yes
17:34	rhg135	cool, a-la-carte tagging would be nice
17:36	arrdem	code review - Either[Success, Failure] mini-lib https://www.refheap.com/95960
17:36	dagda1_	justin_smith: why would next be better in this situation
17:37	arrdem	dagda1_: ∀x (= (seq (rest x)) (next x))
17:38	arrdem	eh I guess that fluokitten has Just, but that's not what I want here.
17:39	AWizzArd	,[(rest nil) (next nil)]
17:39	clojurebot	[() nil]
17:40	bbloom	arrdem: what do you need this for?
17:41	Kristien	I'm about to make a video game in Clojure.
17:42	arrdem	bbloom: this is a beefed-up version of the way that I'm already handling errors in lib-grimoire because you may or may not actually be able to read documentation or examples.
17:43	bbloom	arrdem: errors like when making web requests or something?
17:44	arrdem	bbloom: yep.
17:44	bbloom	arrdem: what should a caller do when they get an error? retry? fail?
17:45	arrdem	bbloom: either, client defined. when Grimoire (which uses this as a backend) gets a failure it has error message display logic.
17:45	bbloom	arrdem: shrug i understand why haskell uses monadic either, but it really seems like you just want exceptions here
17:46	arrdem	bbloom: I did a version of this that used exceptions, but when writing the web error handling logic I found I missed a lot of exception cases and that this was a little easier to reason about.
17:46	AWizzArd	dagda1_: you saw that example? rest vs next?
17:47	bbloom	arrdem: wouldn't a typical client only really have one (or some small number of) top level place where it handles exceptions?
17:47	dagda1_	AWizzArd: yes, next returns nil, that clears it up
17:47	bbloom	rather than error handling logic everywhere
17:49	arrdem	bbloom: agreed which comes with a consequent condemnation of the Grimoire website for not decomplecting datastore access from view rendering enough.
17:50	arrdem	meh
17:57	thheller	dnolen_: I just noticed that asserts in CLJS regenerate the whole assert form on the client
17:57	thheller	(assert (string? bar))
17:57	thheller	https://gist.github.com/thheller/ba1802e6e752097c00f5
17:58	thheller	seems like we can generate that string when compiling no?
17:59	thheller	like throw (new Error("Assert failed: (string? bar)"))?
17:59	bbloom	thheller: probably. should be an easy patch. why not give it a try?
17:59	thheller	just checking ;)
18:02	SagiCZ1	hi, does anyone know if the java call System.loadLibrary() is dependent on a package it is called from? it stops working when i move the source file with this call to a different package
18:34	thheller	CLJS-970 done
18:38	hellofunk	when you open a repl on a project with multiple profiles, how does it know which profile to select?
18:43	arohner	hellofunk: I'm pretty sure it uses a default profile (I don't know which one that is)
18:44	arohner	it's probably like dev+repl or something
18:53	emaczen	how can I setup/connect a remote repl?
18:55	gfredericks	emaczen: welp.
18:56	gfredericks	emaczen: um
18:56	gfredericks	emaczen: `lein repl` starts an nrepl server and tells you what port it's listening on
18:57	gfredericks	and `lein repl :connect <port-num>` starts an nrepl client
18:57	gfredericks	`lein help repl` might be helpfully detailed
18:57	imanc	is there a short and easy way for running a clj file, equivalent to say: python afile.py
18:57	gfredericks	imanc: there are special plugins and scripts that people have written, but nothing easy built in
18:58	gfredericks	clojure is a java library, not an executable of any sort
18:59	imanc	ok, i thought lein might have made something available equivalent ot lein repl
18:59	gfredericks	imanc: depending on what you consider easy, the fact that the clojure.main class can take a filename and execute it might be helpful
18:59	imanc	lein run afile.clj
18:59	gfredericks	imanc: there's a lein plugin called one-off I think that can do that and has features for dependencies too
18:59	imanc	okay, nice. - i'll check itout
19:01	imanc	gfredericks: is this pretty much the defacto way of running clj files: java -cp clojure.jar clojure.main file.clj
19:01	gfredericks	imanc: well I don't think anybody's happy typing that by hand on a regular basis but otherwise that's a perfectly fine way to do it
19:01	imanc	yeh agreed re's not wanting to type that
19:02	andyf	justin_smith: Regarding you and arrdem discussing get returning nil in many cases, there is a ticket http://dev.clojure.org/jira/browse/CLJ-1107 you could vote on if you agree with the proposed change. Looks like arrdem already has.
19:02	hellofunk	lazybot: are you just a little baby machine wearing tights at home, listening to Kenny G ???
19:02	lazybot	hellofunk: Oh, absolutely.
19:03	arrdem	andyf: I vote on most things :P
19:04	andyf	You and Bronsa :)
19:04	arrdem	yeah but Bronsa actually submits lots of good patches. I just complain and work on docs :P
19:04	andyf	well one of those is helpful to others :)
19:05	arrdem	http://i.imgur.com/88VdCIO.png hence I try not to post :D
19:07	emaczen	gfredericks: I've been trying lein repl :connect http://host:port/repl without any success
19:08	emaczen	gfredericks: I'm using the Luminus framework, if that helps
19:09	imanc	so if i installed clojure via the lein installation script, where would clojure.clj be?
19:11	gfredericks	emaczen: oh this is clojurescript? if so then I have no idea
19:11	AWizzArd	imanc: you can find the clojure.clj in home/.m2/repository/org/clojure/clojure/1.6.0/clojure.jar
19:13	imanc	AWizzArd: nah, i can go as far as : /.m2/repository/org/clojure but in that directory i just have pom.contrib and tools.nrepl with no clojure.clj in those directories
19:14	AWizzArd	Then the clojure.jar was probably not downloaded yet.
19:14	imanc	AWizzArd: lein repl works tho? Does that not rely on clojure.jar?
19:14	AWizzArd	When doing “lein deps” it should somewhere say that it fetched clojure.jar
19:15	imanc	oo Couldn't find project.clj, which is needed for deps
19:15	imanc	ah OK
19:16	AWizzArd	Indeed, Leiningen depends on Clojure. And when you inspect ~/.lein/self-installs/leiningen-2.5.0-standalone.jar, then you’ll find that Clojure is inside there.
19:16	AWizzArd	This however is a specific version which Leiningen depends on. Your own project might want to use a totally different version.
19:16	wei	is there a good way to export a memory datamic db? i was running a test instance but now have data i want to keep..
19:18	imanc	AWizzArd: yeh, I just created a random .clj file (not a full project) and wanted to run it. i've now done lein new myproj and a lein deps
19:20	AWizzArd	imanc: in principle you can create a temp dir and place a file project.clj inside. Into this file you write something like (defproject com.imanc/foo "0.1.0" :dependencies [[org.clojure/clojure "1.6.0"]])
19:20	AWizzArd	Then you could try “lein repl” and see if that works. Also checking that .m2 path from above again. Chances are that this will indeed download the clojure.jar
19:20	emaczen	gfredericks: This is not clojurescript.
19:22	Bronsa	arrdem: I vote an all the things :P
19:23	imanc	AWizzArd: thanks. lein deps on a test project created the file - it is called clojure-1.6.0.jar though
19:24	AWizzArd	Yes yes, that’s correct.
19:26	gfredericks	emaczen: okay so where did that url come from? nrepl uses tcp sockets not http
19:27	emaczen	gfredericks: I've seen this on stackoverflow
19:27	emaczen	gfredericks: exactly how do you have your server setup?
19:27	gfredericks	emaczen: I'm not sure what you're trying to accomplish; "remote repl" is a bit ambiguous
19:29	arrdem	Okay, so for the "platform" component of a Grimoire URL what would you use... the Clojure JIRA abbrev for a Clojure dialect or something else?
19:31	emaczen	gfredericks: I'm trying to learn how to connect to a repl (figuring out how on localhost is fine)
19:32	emaczen	gfredericks: Right now, I just ran `lein ring server` to start my clojure program running locally on port 3000
19:34	emaczen	gfredericks: If I do `M-x cider-jack-in` locally everything just seems to work (so now I'm trying to get this to work on a remote server, and connect with cider from my laptop)
19:35	gfredericks	emaczen: so you're running a web server? and you want to connect to a repl on the same jvm process as your http server?
19:38	gfredericks	emaczen: cider-jack-in always starts a new jvm btw
19:40	gfredericks	emaczen: there might be ring-related plugins for this already, but if nothing else you can start an nrepl server this way: https://github.com/clojure/tools.nrepl#embedding-nrepl-starting-a-server
19:40	weavejester	Lein-Ring can be started with nrepl
19:40	weavejester	Though I tend to just use component-based REPLs these days
19:44	AWizzArd	weavejester: what do you mean by “component-based”?
19:46	weavejester	AWizzArd: A design based around Stuart Sierra's component library and "reloaded workflow" design.
20:50	gfredericks	I just thought of a basic clojure-evaluation question that I didn't know the answer to
20:50	gfredericks	,(defmacro make-if [] 'if)
20:50	clojurebot	#'sandbox/make-if
20:50	gfredericks	,((make-if) 1 2 3)
20:50	clojurebot	#<CompilerException java.lang.RuntimeException: Unable to resolve symbol: if in this context, compiling:(NO_SOURCE_PATH:0:0)>
21:09	ajmagnifico	http://onclojure.com/2009/03/05/a-monad-tutorial-for-clojure-programmers-part-1/
21:09	ajmagnifico	Tried that link from the page at https://github.com/clojure/algo.monads
21:09	ajmagnifico	says the domain has expired. Does anyone have an updated link?
21:10	gfredericks	ajmagnifico: have you checked at archive.org?
21:12	ajmagnifico	gfredericks: excellent idea, thanks. I found it there.
21:18	[Blake]	Anyone up for design discussion?
21:50	arrdem	[Blake]: shoot
21:53	[Blake]	OK. I'm writing a theme park type game. I have little plots of land the player can buy and build stuff on. People walk around, get in each other's way, try to see some things and avoid others. Etc.
21:54	arrdem	Sure
21:55	[Blake]	So I'm trying to figure out how to put all the pieces together. Like...it's easy enough to say "This guy walks from this point to that point" on a plot of land.
21:58	[Blake]	It gets harder when there are multiple plots. And plots of land (so far) are plain. But rides have all kinds of info describing them, and getting on them involves getting into a entry queue, on to the ride, and getting into an exit queue (before going back to a plot of land).
21:59	[Blake]	So I'm favoring have a master list of everything that responds to a clock tick. And another list of, say, people and their locations (if they're on a ride or whatever).
21:59	[Blake]	Oh, I'm using an entity-system type thing: Everything in the game has a unique ID.
22:02	[Blake]	That's where I get stuck, I think: At the begining of each turn, I assess the order of actions. And each thing that can act has its own "act" method. Polymorphism. But I'm not sure I'm not just carrying OO baggae.
22:02	[Blake]	er baggage
22:09	swedishfish	sdegutis: have you watched this? https://www.youtube.com/watch?v=P76Vbsk_3J0
22:13	arrdem	[Blake]: So I think that it's reasonable to have things that "tick" but I'd be careful with how your player interacts with this state.
22:17	[Blake]	arrdem: So, I have this master list of people, rides, service techs, natural events (fire, flood)...there's a tick and I get a list of everything that "moves" this turn.
22:17	[Blake]	I guess I just dynamically dispatch based on type?
22:17	arrdem	Yep.
22:17	arrdem	Protocols FTW
22:18	[Blake]	Heh. OK, well, I guess I shouldn't stress it. I'll do it and learn.
22:18	arrdem	Clojure: what's the worst that can happen? It's immutable.
22:19	[Blake]	I'm not too worried about the player interaction. The player is mostly indirect.
22:19	arrdem	I'm just mentioning the player because a callback based player has really wrought hell in one of my side projects.
22:19	[Blake]	arrdem: I guess my big fear is that I can see passing the entire game state around all over and that seems so very--not in the spirit of Clojure.
22:20	[Blake]	arrdem: Ooh. So...the player triggers code that can disrupt things?
22:20	[Blake]	How...functionally reactive.
22:20	arrdem	sorta kinda
22:20	arrdem	The issue is that there are dice rolls where players may choose outocomes
22:20	[Blake]	'k
22:21	arrdem	so you have your grand "turn", but while stuff is resolving there are decision points
22:21	arrdem	so it's not like Event -> Event -> Event, there are these weird contexts
22:23	[Blake]	arrdem: Interesting. That sounds like it's complex by nature.
22:24	arrdem	[Blake]: sadly
22:24	[Blake]	heh...well, that can be fun (to play if not program)
22:24	arrdem	it makes building an AI player hard because you could fail a dice roll and have to re-plan
22:24	arrdem	$google privateer press warmachine
22:24	lazybot	[WARMACHINE \| Privateer Press] http://privateerpress.com/warmachine
22:25	[Blake]	arrdem: Oh, jeez, yeah. I haven't been into gaming much in recent years but bad AI was the norm when I was.
22:25	arrdem	basically the entire game is based on taking 2d6+base >= stat checks
22:26	arrdem	so thinking about this: http://swannodette.github.io/2015/01/09/life-with-dynamic-typing/
22:26	arrdem	is it acceptable to do the same thing with a protocol?
22:27	arrdem	I've never seen it done, but it seems like it should be...
22:27	sdegutis	swedishfish: youtube's blocked so no
22:28	[Blake]	(reading)
22:29	arrdem	s/protocol/multimethod/g
22:30	[Blake]	So...assertions with protocols/multimethods?
22:31	arrdem	yeah
22:32	arrdem	What I've been doing is putting assertions on multimethod imp'ls and lifting them to defs, but putting assertions at the API layer in the multimethod would be nice
22:33	[Blake]	arrdem: I could see that working, at least in theory. I've only done a few multimethods so far.
22:35	[Blake]	But it reminds me a lot of Eiffel, the contract pre/post stuff.
22:48	[Blake]	OK, so the way I see it, I'm going to have a "location list". Every object in the game will have an entry in the list saying where it is. So people are on certain plots of land or on particular rides. Rides are on particular plots of land. I think that'll work. That'll be the most dynamic, vis a vis state.
22:49	[Blake]	I mean, I have to keep a bunch of lists for each game-object that can contain other game-objects, but a master list means I can ask "Where is object X" without having to iterate over all the lists.
22:51	arrdem	Sounds reasonable to me
22:51	tomjack	[Blake]: why not use a map instead of a list of entries?
22:52	[Blake]	tomjack: Yeah, it'll be a map objid=>whereitis. I was using "list" casually.
23:01	tomjack	speaking of maps as quotients of sequentials..
23:01	tomjack	(defn concat' [x y] {:post [(if (= x nil) (= % y) true)]} (concat x y))
23:02	justin_smith	[Blake]: the location list thing reminds me of the component entity system dedign
23:03	tomjack	I guess maybe we want (nil? (seq x)) or something in the :post
23:03	tomjack	is this a badly placed runtime assertion?
23:04	justin_smith	tomjack: (empty? x) would be better
23:04	tomjack	sure
23:04	[Blake]	justin_smith: Yeah, that's what I'm doing. Everything's split up into lists, which is cool for processing. But trying to organize all the processes...it's not intuitive, you know? It's not like "Here's a park. Here's a ride. Here's a person."
23:04	tomjack	is the benefit from a type system which can express this postcondition not an immediate benefit of stronger types? :)
23:05	tomjack	also, that's just left unit. how about associativity of concat?
23:06	tomjack	presumably there is an implicit "the immediate benefit of stronger types [in type systems which have practical implementations today]"
23:07	justin_smith	tomjack: what does associativity mesn in this context?
23:08	tomjack	(prop/for-all [x _ y _ z _] (= (concat' x (concat' y z)) (concat' (concat' x y) z)))
23:09	arrdem	Dependent type systems like Agda and Idris can prove that
23:09	arrdem	but they're very much research efforts still
23:09	arrdem	give it a couple years
23:10	tomjack	yes, hence the presumable "practical implementations today" qualification, which is a totally reasonable qualification :)
23:11	tomjack	the concat' above fails for e.g. args '(nil {}) because (not= () {})
23:15	justin_smith	tomjack: and ##(not= nil ())
23:15	lazybot	⇒ true
23:17	tomjack	yeah, that postcondition is bad, just an example
23:18	justin_smith	that's an easy gotcha to run into if Clojure is not your first lisp
23:19	cursivecode	I've read multimethods are slow. Are they just slow relative to protocols, or are they slow in general? ... if I used a bunch of conditionals would it be the same as using multimethods?
23:19	tomjack	I guess that "stronger types [with a practical language today]" is mostly about catching errors you can catch easily with pre/post, and the errors you catch in e.g. test.check tests are "stronger types [with a practical language maybe someday]"
23:20	arrdem	cursivecode: slower by ~5-10x than a protocol if I remember @mikera's numbers
23:21	cursivecode	Does anyone know if there's a performance difference in Clojurescript?
23:22	cursivecode	arrdem: thanks
23:28	rritoch	Does anyone know if there is a proof, that LISP is the ideal syntax for a "functional" language? By functional I simply mean a language without operators, not the typical usage of functional. I've been doing some work trying to build a C like grammer with typedef's and dynamic operators and have run into ambiguity cases that can only be resolved at runtime.
23:31	rritoch	I made a few estimates and calculations and it seems that replacing operators with functions would be more efficient than checking the "type" of a symbol each time a symbol is "seen" by the parser. This lead me to a conclusion that a language without operators would is possibly the most efficient language that can exist with dynamic operators.
23:32	rritoch	err, would be/is possibly
23:33	rritoch	I'm just wondering if there is any scientific or mathematical proofs which actually define the LISP syntax as being the optimal syntax when there is a need to add operators at runtime.
23:35	arrdem	You're asking for a proof of compression optimality, which is an NP hard problem. I'm gonna take a shot in the dark here: Non-optimal, the proof is left as an exercise to the reader.
23:37	rritoch	arrdem: Thanks, that answers my question. My estimates were all related to the number of operations it takes to resolve a symbol to a type, vs the number of operations it takes to do a search/replace. Getting hard data for that would be difficult, if not impossible.
23:38	rritoch	arrdem: With my limited programming language development experience though, even if it is not provable, it does seem that LISP is the ideal syntax for adding "operators" at runtime.
23:41	rritoch	arrdem: At this point I've reverted from trying to make proof of concept implementation back to the theoretical/research phase since the cost of dynamic operators in an algorithmic language seems to be quite high, both in terms of CPU usage and memory usage.
23:51	rritoch	On a more positive note. I've proven that the lein-sablecc plugin I developed is fully functional. I was able to build a language and interpreter with it, but things fell apart as soon as I tried to add operators at runtime. More specifically, it would be consulting an object defined with the language during compilation of new sources to determine new operators.
23:56	arrdem	What utility do you see that adding to a langauge beyond complexity