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clojurians | clojure | think about what you are actually feeding a chan for instance when you provide a xf argument | 2017-11-07T21:36:40.000017 | Evelin |
clojurians | clojure | you are giving it a function that is composed of transducers (other functions) | 2017-11-07T21:36:53.000034 | Evelin |
clojurians | clojure | it has to be composed of transducers, nothing else | 2017-11-07T21:37:01.000124 | Evelin |
clojurians | clojure | you can't for instance, give it just a general expression that expects a value in a particular place and can use any function ("transducible" or otherwise) | 2017-11-07T21:37:45.000179 | Evelin |
clojurians | clojure | you also can't just give it any old function | 2017-11-07T21:37:57.000022 | Evelin |
clojurians | clojure | and expect it to work, even if the dimensionality and data types match up | 2017-11-07T21:38:13.000044 | Evelin |
clojurians | clojure | atleast not as exepcted | 2017-11-07T21:38:18.000138 | Evelin |
clojurians | clojure | IF the transducible process had the macro capability to look inside what you gave it | 2017-11-07T21:38:41.000101 | Evelin |
clojurians | clojure | THEN it could decide for itself what it can do, whether it has to break up some things or rearrange others into what we are calling "transducible process" | 2017-11-07T21:39:04.000082 | Evelin |
clojurians | clojure | it could even rearrange things or break things up in more particular ways that are specific to the thing being worked on | 2017-11-07T21:39:21.000142 | Evelin |
clojurians | clojure | chan in this instance | 2017-11-07T21:39:26.000011 | Evelin |
clojurians | clojure | this is what async/go actually does | 2017-11-07T21:39:48.000160 | Evelin |
clojurians | clojure | it breaks up your s-expression and creates a state machine out of it | 2017-11-07T21:40:00.000134 | Evelin |
clojurians | clojure | transducers were a great way to follow DRY, but i feel like it was a missed opportunity to just fix the real issue | 2017-11-07T21:40:34.000103 | Evelin |
clojurians | clojure | can you give an example of what you would like the code to look like? | 2017-11-07T21:41:08.000070 | Jonas |
clojurians | clojure | i feel like it’s hard to be more concise than `(chan 1 (map inc))`, | 2017-11-07T21:42:14.000129 | Jonas |
clojurians | clojure | i'd like to say `(map dec (filter even? (reduce conj [] (foo bar (xan zoo WHATEVER)))))` and have clojure know how to optimally unravel it so that it doesn't create more intermediate sequences than necessary, can do what is effectively known as a "transducible process" (doing things in one pass) on either side of the reduce, and can even do things in parallel if it can use the runtime to judge that doing so doesn't alter the semantics of what you are doing (it can't if you are just using immutable values) and if doing so would result in faster computation even after taking into account the overhead involved with concurrency. | 2017-11-07T21:45:04.000039 | Evelin |
clojurians | clojure | in other words, the details exposed to us in the transducer api shouldn't really have to be exposed to us-- if that is how things need to work between "transducible processes" well ok, but why should i be bothered with it? | 2017-11-07T21:45:40.000259 | Evelin |
clojurians | clojure | that sort of thing belongs in the implementation of eval | 2017-11-07T21:45:51.000009 | Evelin |
clojurians | clojure | the fact that making new transducers means they have to do this and this and that, why do i care? | 2017-11-07T21:46:17.000058 | Evelin |
clojurians | clojure | can't eval look at what i'm giving it and verify that i've done these things? | 2017-11-07T21:46:27.000136 | Evelin |
clojurians | clojure | if i want to express the idea of a computation without the thing being computed, i can just say `(map dec (filter even? (reduce conj [] (foo bar (xan zoo)))))` | 2017-11-07T21:47:02.000163 | Evelin |
clojurians | clojure | notice the lack of WHATEVER | 2017-11-07T21:47:06.000069 | Evelin |
clojurians | clojure | i just pass it as an s-expression and someone can inject whatever they want into it and then evaluate it | 2017-11-07T21:47:30.000103 | Evelin |
clojurians | clojure | imho transducers just don't feel very lispy | 2017-11-07T21:47:41.000257 | Evelin |
clojurians | clojure | they work well for what they try to do, but it sort of misses the point of lisp | 2017-11-07T21:48:01.000050 | Evelin |
clojurians | clojure | Verify that I've done these things is different than doing them automatically, though. | 2017-11-07T21:48:10.000007 | Giovanna |
clojurians | clojure | Imho what you're describing sounds more haskelly than clojurey | 2017-11-07T21:48:31.000030 | Giovanna |
clojurians | clojure | it would be cool if the compiler would take my clojure code and optimize/parallelize it for me, but that seems like a separate issue than the design of transducers | 2017-11-07T21:49:44.000042 | Jonas |
clojurians | clojure | yeah its sort of a bigger issue | 2017-11-07T21:49:57.000031 | Evelin |
clojurians | clojure | i guess i tend to think that ideally programs should just say what it is, semantically, that you want to do | 2017-11-07T21:50:56.000043 | Evelin |
clojurians | clojure | the question of how that is done or how to make it performant is a completely separate and orthogonal concern | 2017-11-07T21:51:12.000013 | Evelin |
clojurians | clojure | usually best solved in the complier or evalutor | 2017-11-07T21:51:23.000104 | Evelin |
clojurians | clojure | i don't like it when programming languages ask you to make them faster by instructing them on how to do the compiler's job | 2017-11-07T21:51:45.000086 | Evelin |
clojurians | clojure | I think that's kind of not the clojure way, though. Like the difference between `last` and `peek` on a vector. | 2017-11-07T21:52:17.000223 | Giovanna |
clojurians | clojure | Semantically they're the same, but one's way faster | 2017-11-07T21:53:29.000081 | Giovanna |
clojurians | clojure | yeah i guess i just have a different opinion on the matter | 2017-11-07T21:53:47.000103 | Evelin |
clojurians | clojure | you are right it probably isn't the clojure way | 2017-11-07T21:53:51.000226 | Evelin |
clojurians | clojure | heck it probably isn't even a very popular view on things | 2017-11-07T21:54:01.000036 | Evelin |
clojurians | clojure | oh well i'll stop ranting | 2017-11-07T21:54:06.000011 | Evelin |
clojurians | clojure | thanks for hearing me out though | 2017-11-07T21:54:11.000123 | Evelin |
clojurians | clojure | Hmm, I couldn't find that in the transcript <https://github.com/matthiasn/talk-transcripts/blob/master/Hickey_Rich/EffectivePrograms.md> | 2017-11-07T21:54:34.000134 | Daniell |
clojurians | clojure | Yeah, I remember hearing/reading it longer ago than the conj.... I have a crappy memory though, so you never know ¯\_(ツ)_/¯ | 2017-11-07T21:56:22.000210 | Giovanna |
clojurians | clojure | I think it's very valid to question things :slightly_smiling_face: Rich is not a messiah and blindly following him is not good for anyone. | 2017-11-07T22:02:38.000087 | Giovanna |
clojurians | clojure | What you're saying about a sufficiently smart compiler/macro really reminds me of both criticism and praise about haskell though. Where it can do some really cool optimizations, but that makes it hard to reason about perf. | 2017-11-07T22:02:40.000196 | Giovanna |
clojurians | clojure | Re: writing your own transducing functions -- I wrote one that turned flat sequences of maps into sequences of threaded sequences of maps (based on certain fields acting as keys and back references). It turned out to be a very elegant solution to creating threaded conversations out of raw sequences of messages between members. It hid the complexity of the problem and it was easily composable with any other processing I wanted to do on messages (before transformation) or conversations (after transformation). | 2017-11-07T22:07:24.000065 | Daniell |
clojurians | clojure | <@Evelin> there's a lot of compiler tech out there that does this sort of thing. PyPy does it out-of-the-box at runtime, infact PyPy actually runs transducers over int arrays faster than Clojure. ClojureScript does as well. Clang can do this sort of stuff but it would require all your pipelines to be defined up-front and fully static | 2017-11-07T23:43:04.000201 | Sandy |
clojurians | clojure | The beauty of the Clojure model, is that none of this took compiler support. It just works as a library. | 2017-11-07T23:43:52.000132 | Sandy |
clojurians | clojure | That's the problem with a lot of these approaches. PyPy took 3-4 people 10 years to engineer. The JS JITs took less time, but larger teams. Transducers were mostly designed in about 3 weeks by one person. | 2017-11-07T23:44:35.000034 | Sandy |
clojurians | clojure | And you'll see that pattern throughout Clojure, never over-engineer. If you can accomplish what you need with your existing tools, do it that way. | 2017-11-07T23:45:11.000031 | Sandy |
clojurians | clojure | Not saying these other methods aren't valid, but they are much more complicated. | 2017-11-07T23:45:38.000046 | Sandy |
clojurians | clojure | And for anyone here interested, here's pretty much the state-of-the-art for this sort of thing. From the Scala world, but the paper goes over Lisp and the like as well: <https://infoscience.epfl.ch/record/180642/files/EPFL_TH5456.pdf> | 2017-11-08T00:08:00.000094 | Sandy |
clojurians | clojure | That's a big paper! Won't start it tonight :slightly_smiling_face: | 2017-11-08T00:09:44.000136 | Bibi |
clojurians | clojure | yeah the first 50 pages or so are an overview of why we need this thing | 2017-11-08T00:10:50.000197 | Sandy |
clojurians | clojure | <@Sandy>: can you tell <https://www.youtube.com/channel/UC6yONKYeoE2P3bsahDtsimg/videos> to create a video walkthrough of the paper, step by step, implementing a minimal setup in clojure ? | 2017-11-08T00:15:37.000068 | Berry |
clojurians | clojure | Heh, most of it leans really heavily on static typing. How to adapt it to more dynamic languages is still a WIP | 2017-11-08T01:00:38.000128 | Sandy |
clojurians | clojure | Were Clojure's transducers only able to be made so quickly because of the way the language is, or does putting them in the compiler just take longer? Since it's lispy i'm just curious if impossible to do it the library way in other languages. | 2017-11-08T01:03:07.000203 | Janette |
clojurians | clojure | It would be nice if there was something like defmacro that did not evaluate its arguments but that could return a value instead of code that gets evaluated. Is such a thing possible? | 2017-11-08T02:05:02.000013 | Alix |
clojurians | clojure | <@Alix> well, it is possible as long as the value can be expressed as code... Isn't this what `comment` does ?
```
(defmacro comment [& body] nil)
``` | 2017-11-08T03:48:57.000264 | Danyel |
clojurians | clojure | Could anybody help me with fuzzy multi-method dispatching? Say, I have maps with `:os` and `:version` fields. Basically, I need to dispatch them by OS, but for some specific versions I need to perform some other logic. What I’m trying to reach is:
```
;; let's say my dispatcher function is (juxt :os :version)
[:mac <any-version>] ==> the standard iOS algorithm
[:win <any-version>] ==>> the standard Windows algorithm
;; but!
[:mac :11.22.33] == > some Mac-specific algorithm for version 11.22.33
```
So once I’ve got some another buggy version, I just add another `(defmethod...)` definition for that case. Probably, later I’ll need to add more minor keys to dispatch, say, browser name or something else.
I’ve tried a bit `derive` and custom hierarchies but without success. | 2017-11-08T04:02:05.000036 | Verna |
clojurians | clojure | <@Verna> <http://clojuredocs.org/clojure.core/defmulti#example-57558046e4b0bafd3e2a0474> | 2017-11-08T04:07:31.000336 | Randee |
clojurians | clojure | yes I’ve seen that example but cannot understand it completely so it prevents me from using it. | 2017-11-08T04:08:32.000039 | Verna |
clojurians | clojure | <@Verna> What's the question? I wrote that example :slightly_smiling_face: | 2017-11-08T04:08:49.000380 | Randee |
clojurians | clojure | Basically: 1. If no 100% match, find the default method in the `:default` fallback. 2. Add this fallback to the defmulti | 2017-11-08T04:09:34.000315 | Randee |
clojurians | clojure | <@Randee> makes sense. Another solution might be to derive any version over `::default` value once I’ve got that map. | 2017-11-08T04:12:26.000044 | Verna |
clojurians | clojure | sorry, i was mistaken - it's the Inside Transducers talk | 2017-11-08T04:54:41.000063 | Evan |
clojurians | clojure | >>>Who knows what the semantics of reduce are when you call it with a collection and no initial value?
[Audience response]
No one, right. No one knows. It's a ridiculous, complex rule. It's one of the worst things I ever copied from Common Lisp was definitely the semantics of reduce. It's very complex. If there's nothing, it does one thing. If there's one thing, it does a different thing. If there's more than one thing, it does another thing. It's much more straightforward to have it be monoidal and just use f to create the initial value. That's what transduce does, so transduce says, "If you don't supply me any information, f with no arguments better give me an initial value." | 2017-11-08T04:55:36.000376 | Evan |
clojurians | clojure | well, transducers are very simple, language-agnostic concept - there are (library) implementations for javascript, ruby, python, and java as well | 2017-11-08T05:16:48.000355 | Evan |
clojurians | clojure | tim's point was just that transducers were invented in a very short time, and required no compiler support at all | 2017-11-08T05:18:02.000054 | Evan |
clojurians | clojure | <@Verna> Why not use something like this:
```
(derive :mac/high-sierra :mac/default)
=> nil
(isa? :mac/high-sierra :mac/default)
=> true
```` | 2017-11-08T05:38:48.000320 | Taina |
clojurians | clojure | and derive all the os-versions from a default version. | 2017-11-08T05:39:11.000541 | Taina |
clojurians | clojure | <@Taina> yes, it came to me afterwards. I’m going to derive version once I get a map to dispatch. | 2017-11-08T05:40:07.000275 | Verna |
clojurians | clojure | <@Verna> :slightly_smiling_face: Happy hacking. | 2017-11-08T05:40:58.000336 | Taina |
clojurians | clojure | <@Sonny> or other Cognitect folks -- I noticed that the instructions in the `readme.txt` in the Clojure repo are no longer complete and accurate -- I can build with ant or maven, but `java -cp clojure-${VERSION}.jar clojure.main` no longer works; it throws an exception because of the spec dependency. Maybe worth adding a note to readme that spec has to be built and installed first? Note: I'm assuming that's what has to be done to fix; I haven't actually tried it at this point.
Didn't seem worth filing a ticket, since it's so minor, but a suggestion for the final 1.9 release. | 2017-11-08T09:11:39.000002 | Lavenia |
clojurians | clojure | Just seems like it could trip up new users who are naively trying to follow the instructions in the readme. | 2017-11-08T09:12:24.000397 | Lavenia |
clojurians | clojure | <@Lavenia> this is a known issue, and being addressed with the `clj` tool | 2017-11-08T09:14:17.000311 | Margaret |
clojurians | clojure | it will be integrated (including the readme) when 1.9 is the stable release, is what I heard | 2017-11-08T09:14:49.000184 | Margaret |
clojurians | clojure | Right, I'm aware of the new CLI tool -- just suggesting that the readme be updated. | 2017-11-08T09:15:07.000418 | Lavenia |
clojurians | clojure | Cool, good to know; just wanted to be sure it hadn't been overlooked. | 2017-11-08T09:15:22.000137 | Lavenia |
clojurians | clojure | what new CLI tool? | 2017-11-08T09:51:14.000002 | Lester |
clojurians | clojure | the tool is called clj, it's clojure.core plus a dependency manager to bootstrap | 2017-11-08T09:51:45.000389 | Margaret |
clojurians | clojure | since clojure.core now needs other libraries to run | 2017-11-08T09:51:54.000548 | Margaret |
clojurians | clojure | ah, I see | 2017-11-08T09:54:31.000565 | Lester |
clojurians | clojure | There are several things in that readme that are lagging and need updating. We don’t plan to make any more changes for 1.9 though. | 2017-11-08T10:05:23.000487 | Sonny |
clojurians | clojure | <https://clojure.org/guides/deps_and_cli> | 2017-11-08T10:05:54.000425 | Sonny |
clojurians | clojure | Why were those other libs not merged into `clojure.core` to make sure it could run standalone? | 2017-11-08T10:07:12.000778 | Mallie |
clojurians | clojure | they were originally in core and we split them out to allow them to be updated independently from core | 2017-11-08T10:07:46.000330 | Sonny |
clojurians | clojure | Fair enough | 2017-11-08T10:07:59.000458 | Mallie |
clojurians | clojure | <https://groups.google.com/forum/#!msg/clojure/10dbF7w2IQo/ec37TzP5AQAJ> | 2017-11-08T10:08:08.000215 | Sonny |
clojurians | clojure | Does anyone know a way how to genereate documentation out of plumatic/schema ? | 2017-11-08T10:08:09.000645 | So |
clojurians | clojure | <@So> what kind of documentation are you looking for? | 2017-11-08T10:46:01.000600 | Ava |
clojurians | clojure | <@So> ```user=> (s/defn foo :- Bar
#_=> [qux :- s/Str, quux :- [s/Keyword]])
#'user/foo
user=> (doc foo)
-------------------------
user/foo
([qux quux])
Inputs: [qux :- s/Str quux :- [s/Keyword]]
Returns: Bar
``` | 2017-11-08T10:49:57.000057 | Ava |
clojurians | clojure | Yeah, `reduce` is ... weird. When I first implemented `reducible-query` in `clojure.java.jdbc` I got the no-init arity of `reduce` wrong because I assumed the semantics of `transduce`. The `reduce` docstring is very clear -- the behavior is just a bit non-intuitive. | 2017-11-08T11:48:27.000894 | Daniell |
clojurians | clojure | How do you idiomatically spell `(is (thrown-with-msg? ...))` except also binding the exception to a name so I can `ex-data` it? | 2017-11-08T12:17:15.000454 | Georgianne |
clojurians | clojure | @bla The first prototype I've writen as comment (see: <https://github.com/DomainDrivenArchitecture/dda-serverspec-crate/tree/development>) | 2017-11-08T12:29:39.000363 | So |
clojurians | clojure | like ```
(def ServerTestConfig {
(optional-key :netcat-test)
{Keyword {:reachable? Bool}}, ; keyword is used to match test against fact
(optional-key :netcat-fact) ; parsed result of "nc [host] -w [timeout] && echo $?"
{Keyword {:port Num,
:host Str, ; may be ip or fqdn
:timeout Num}}, ; timeout given in seconds
(optional-key :netstat-test)
``` | 2017-11-08T12:30:35.000862 | So |
clojurians | clojure | But the datatypes described here are splittet across several modules, so we will need a way to
1. add documentation as meta to elements like 'keyword' or 'defschema'
2. a way to render documentation on schema endpoints (sth. like `explain`) | 2017-11-08T12:33:09.000243 | So |
clojurians | clojure | quoting doc of is: ```(is (thrown? c body)) checks that an instance of c is thrown from
body, fails if not; then returns the thing thrown.``` - so at the very least, thrown? lets you do that | 2017-11-08T12:48:39.000192 | Margaret |
clojurians | clojure | <@Georgianne> - looks like it works with thrown-with-msg? too ```kingfisher.core=> (clojure.test/is (thrown-with-msg? Exception #"foo" (/ 1 0)))
FAIL in () (form-init2223331148129063339.clj:1)
expected: (thrown-with-msg? Exception #"foo" (/ 1 0))
actual: #error {
:cause "Divide by zero"
:via
[{:type java.lang.ArithmeticException
:message "Divide by zero"
:at [clojure.lang.Numbers divide "Numbers.java" 158]}]
:trace
...
kingfisher.core=> (type *1)
java.lang.ArithmeticException``` | 2017-11-08T12:51:07.000125 | Margaret |
clojurians | clojure | so the pattern would be to put the `is` in a let block so you can make other assertions about the ex-data | 2017-11-08T12:51:52.000182 | Margaret |
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