Re: Why don't extends? and satisfies? require implementation of all protocol methods?

[Tassilo Horn]

Garth Sheldon-Coulson garth.sheldoncoul...@gmail.com writes:

Hi Garth,

 I'm returning to Clojure in earnest for the first time since 1.1 (and
 very happy to be back!). Apologies if this question revisits old
 issues.

I've revisited mostly the same 2 days ago: 87399ocg9a@thinkpad.tsdh.de

 I'm trying to understand why the semantics of protocols are such that
 the third statement here returns true:

 user= (defprotocol Bashable (bash [this]) (boom [this]))
 Bashable

 user= (defrecord Record [] Bashable (bash [this] bash!))
 user.Record

 user= (and (satisfies? Bashable (Record.)) (extends? Bashable
 Record))
 true

 This returns true even though boom is not implemented for Record:

 user= (boom (Record.))
 AbstractMethodError user.Record.boom()Ljava/lang/Object;  user/eval55
 (NO_SOURCE_FILE:3)

 Apparently, types/records can implement a protocol in name only.

What do you mean with in name only?

 What is behind this choice? Intuitively, I would have conceived of a
 protocol as a collection of methods all of which must be implemented
 in order for a type/record to extend the protocol.

I think it would be nice if extends?/satisfies? would return the set of
implemented methods, say, as keywords.  Then you could check if an
object implements exactly the methods that your function wants to call.

 A second question. How does one explicitly extend a protocol per the
 documentation of the extenders function? Intuitively, I would have
 thought that the code above explicitly extends Bashable if it
 extends Bashable at all. Yet:

 user= (extenders Bashable)
 nil

That was my initial question in my posting two days ago.  extenders
returns only types that extend a protocol using the `extend' function
(or `extend-type', `extend-protocol' macros).  So this works:

  user (defprotocol Bashable (bash [this]) (boom [this]))
  Bashable
  user (defrecord Record [])
  user.Record
  user (extend-protocol Bashable
   Record (bash [_] Bash!))
  nil
  user (extenders Bashable)
  (user.Record)

IMO, that behavior is not very obvious.

OTOH, Stu said that extenders is specific to the extend form (as
suggested by its name), and in fact, neither defrecord's nor deftype's
documentation speak of extending a protocol, but their terminology is to
supply method implementations for protocol methods.

But then, what's the use case of `extenders' anyway?  I mean, I want to
know what types participate in a protocol.  I don't care if they do
because they were explicitly extended to the protocol or because the
method implementations were provided directly in their definition form.
That's an implementation detail I shouldn't have to bother with...

Bye,
Tassilo

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Re: Why don't extends? and satisfies? require implementation of all protocol methods?

[David Powell]

When you create a protocol, as an implementation detail, it also creates a
Java interface.

When you list protocols in a deftype or defrecord form, the generated class
actually implements that Java interface.  And protocol calls to that type
call through the interface. This gives the best performance.

If you add protocols to an existing class, record or type; this dispatch is
done dynamically and interfaces aren't involved.

-- 
Dave
On Mar 7, 2012 8:09 AM, Tassilo Horn tass...@member.fsf.org wrote:

 Garth Sheldon-Coulson garth.sheldoncoul...@gmail.com writes:

 Hi Garth,

  I'm returning to Clojure in earnest for the first time since 1.1 (and
  very happy to be back!). Apologies if this question revisits old
  issues.

 I've revisited mostly the same 2 days ago: 
 87399ocg9a@thinkpad.tsdh.de

  I'm trying to understand why the semantics of protocols are such that
  the third statement here returns true:
 
  user= (defprotocol Bashable (bash [this]) (boom [this]))
  Bashable
 
  user= (defrecord Record [] Bashable (bash [this] bash!))
  user.Record
 
  user= (and (satisfies? Bashable (Record.)) (extends? Bashable
  Record))
  true
 
  This returns true even though boom is not implemented for Record:
 
  user= (boom (Record.))
  AbstractMethodError user.Record.boom()Ljava/lang/Object;  user/eval55
  (NO_SOURCE_FILE:3)
 
  Apparently, types/records can implement a protocol in name only.

 What do you mean with in name only?

  What is behind this choice? Intuitively, I would have conceived of a
  protocol as a collection of methods all of which must be implemented
  in order for a type/record to extend the protocol.

 I think it would be nice if extends?/satisfies? would return the set of
 implemented methods, say, as keywords.  Then you could check if an
 object implements exactly the methods that your function wants to call.

  A second question. How does one explicitly extend a protocol per the
  documentation of the extenders function? Intuitively, I would have
  thought that the code above explicitly extends Bashable if it
  extends Bashable at all. Yet:
 
  user= (extenders Bashable)
  nil

 That was my initial question in my posting two days ago.  extenders
 returns only types that extend a protocol using the `extend' function
 (or `extend-type', `extend-protocol' macros).  So this works:

  user (defprotocol Bashable (bash [this]) (boom [this]))
  Bashable
  user (defrecord Record [])
  user.Record
  user (extend-protocol Bashable
   Record (bash [_] Bash!))
  nil
  user (extenders Bashable)
  (user.Record)

 IMO, that behavior is not very obvious.

 OTOH, Stu said that extenders is specific to the extend form (as
 suggested by its name), and in fact, neither defrecord's nor deftype's
 documentation speak of extending a protocol, but their terminology is to
 supply method implementations for protocol methods.

 But then, what's the use case of `extenders' anyway?  I mean, I want to
 know what types participate in a protocol.  I don't care if they do
 because they were explicitly extended to the protocol or because the
 method implementations were provided directly in their definition form.
 That's an implementation detail I shouldn't have to bother with...

 Bye,
 Tassilo

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Re: Why don't extends? and satisfies? require implementation of all protocol methods?

[Tassilo Horn]

David Powell d...@djpowell.net writes:

Hi David,

 When you create a protocol, as an implementation detail, it also
 creates a Java interface.

Is a protocal neccessarily an implementation detail?  I mean, it might
be, but it can also be a public specification of the requirements types
have to satisfy in order to integrate with my lib.

 When you list protocols in a deftype or defrecord form, the generated
 class actually implements that Java interface.  And protocol calls to
 that type call through the interface. This gives the best performance.

 If you add protocols to an existing class, record or type; this
 dispatch is done dynamically and interfaces aren't involved.

That suggests that `extenders' is actually a private function for doing
the dynamic dispatch.  But it's not used at all in clojure.core.  And
it's inconsistent with extends?.

user (defrecord R2 [] Bashable (boom [this] :boom))
user.R2
user (extenders Bashable);; just returns the dynamic extenders
(user.Record)
user (extends? Bashable R2)  ;; does an implements? check as well
true

IMHO, `extenders' should return also types implementing the protocol
interface directly, so that

  (extends? P T) = (some #(= % T) (extenders P))

holds.

Bye,
Tassilo

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Re: Why don't extends? and satisfies? require implementation of all protocol methods?

[Alan Malloy]

On Mar 7, 1:09 am, Tassilo Horn tass...@member.fsf.org wrote:
 David Powell d...@djpowell.net writes:

 Hi David,

  When you create a protocol, as an implementation detail, it also
  creates a Java interface.

 Is a protocal neccessarily an implementation detail?  I mean, it might
 be, but it can also be a public specification of the requirements types
 have to satisfy in order to integrate with my lib.

You misread his assertion. The implementation detail is that an
interface is defined along with each protocol.

  When you list protocols in a deftype or defrecord form, the generated
  class actually implements that Java interface.  And protocol calls to
  that type call through the interface. This gives the best performance.

  If you add protocols to an existing class, record or type; this
  dispatch is done dynamically and interfaces aren't involved.

 That suggests that `extenders' is actually a private function for doing
 the dynamic dispatch.  But it's not used at all in clojure.core.  And
 it's inconsistent with extends?.

I don't really see how it suggests that, but okay. It does appear that
you're right that extenders and extends? are not consistent between
each other.

 user (defrecord R2 [] Bashable (boom [this] :boom))
 user.R2
 user (extenders Bashable)    ;; just returns the dynamic extenders
 (user.Record)
 user (extends? Bashable R2)  ;; does an implements? check as well
 true

 IMHO, `extenders' should return also types implementing the protocol
 interface directly, so that

   (extends? P T) = (some #(= % T) (extenders P))

 holds.

You're entitled to that humble opinion, but it's not really possible
with any kind of reasonable performance. When you implement the
protocol interface directly, no machinery in clojure.core gets
involved at all - you just define a class that implements an
interface. For `extenders` to be able to list Java classes that
implement the interface directly, it would have to walk through every
class loaded in the JVM and check its implemented-interfaces.

Of course, you could make it almost-work, by having deftype/defrecord
emit some special code for hooking into extenders whenever you define
a class in Clojure, but then it would only work for classes defined
within Clojure, and not for Java classes that implement Clojure's
interfaces/protocols. Frankly I think that's worse than just limiting
it to dynamic extenders.

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Re: Why don't extends? and satisfies? require implementation of all protocol methods?

[Tassilo Horn]

Alan Malloy a...@malloys.org writes:

Hi Alan,

 IMHO, `extenders' should return also types implementing the protocol
 interface directly [i.e., deftypes and defrecords], so that

   (extends? P T) = (some #(= % T) (extenders P))

 holds.

 You're entitled to that humble opinion, but it's not really possible
 with any kind of reasonable performance. When you implement the
 protocol interface directly, no machinery in clojure.core gets
 involved at all - you just define a class that implements an
 interface. For `extenders` to be able to list Java classes that
 implement the interface directly, it would have to walk through every
 class loaded in the JVM and check its implemented-interfaces.

 Of course, you could make it almost-work, by having deftype/defrecord
 emit some special code for hooking into extenders whenever you define
 a class in Clojure,

That's what I had in mind.  deftype/defprotocol could just alter the
:impls of the protocol, just like `extend' does.

 but then it would only work for classes defined within Clojure, and
 not for Java classes that implement Clojure's interfaces/protocols.

Well, yes.

 Frankly I think that's worse than just limiting it to dynamic
 extenders.

I'd prefer if it was limited to extenders that extend within clojure,
because that seems to be the more common case.  My use case for
`extenders' was my API docs generator, where I'd like to add to every
protocol description the types that extend that protocol.

So basically, I see 3 options:

  1) rename `extenders' to `dynamic-extenders' (or something like that)
 to get rid of the extends?/extenders inconsistency

  2) remove `extenders' completely (can anyone think of any use case for
 it in its current incarnation that is important enough that it
 justifies a core function instead of using (keys (:impls protocol))
 directly?)

  3) make deftype/defrecord alter the :impls just like `extend' does and
 document the limitation concerning implementing protocol interfaces
 in java explicitly in the `extenders' docstring

I'm happy to provide a patch for either option.

Bye,
Tassilo

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Re: Why don't extends? and satisfies? require implementation of all protocol methods?

[Armando Blancas]

 user= (boom (Record.)) 
 AbstractMethodError user.Record.boom()Ljava/lang/Object;  user/eval55 
 (NO_SOURCE_FILE:3) 

 Apparently, types/records can implement a protocol in name only. 


That can't in name only since you obviously got an implementation, though 
abstract.
 

 What is behind this choice? 


That's convenient when an implementation only cares about a few methods in 
a big protocol.

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Re: How to use goog.dom.query

[Brent Millare]

Have you tried giving the full path in the :libs option?

On Tuesday, January 24, 2012 12:35:00 PM UTC-5, Jonas wrote:

 Hi all

 I was wondering if it's possible to use goog.dom.query[1] from 
 ClojureScript or ClojureScript One? It's a third party module but it's 
 bundled with the Closure version which is downloaded by scripts/bootstrap. 
 I've tried (:require [goog.dom.query :as query]) but that doesn't work out 
 of the box for me. Looking at the source code[2] I can see it referenced 
 several times which makes me hopeful that I should get it working. It seems 
 that maybe I should add 

 :libs [closure/library/third_party/closure]

 or something similar to my build options but still no luck.

 [1]: 
 http://closure-library.googlecode.com/svn/docs/closure_third_party_closure_goog_dojo_dom_query.js.html
 [2]: 
 https://github.com/clojure/clojurescript/blob/master/src/clj/cljs/closure.clj#L555


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Re: Google Summer of Code 2012 - any mentors?

[Alexander Yakushev]

Great job answering the application questions, David! I was just wondering 
if Steve Yegge could vouch for Clojure since I remember him being very 
excited about the language, so maybe he might say a nice word for Clojure 
participation...

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Google Summer of Code 2012 Application

[David Nolen]

I've made some progress here:

http://dev.clojure.org/display/community/Google+Summer+of+Code+2012+Application+Questions

For those with edit right please edit as you see fit and as soon as you
can, we're running out of time, thanks! :)

David

On Wed, Mar 7, 2012 at 1:37 PM, Alexander Yakushev
yakushev.a...@gmail.comwrote:

 Great job answering the application questions, David! I was just wondering
 if Steve Yegge could vouch for Clojure since I remember him being very
 excited about the language, so maybe he might say a nice word for Clojure
 participation...

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Google Summer of Code 2012 Proposal Backup Mentors

[David Nolen]

http://dev.clojure.org/display/community/Google+Summer+of+Code+2012

A reminder that we're still looking for proposals from community members
and interested students. We're also looking for backup mentors - if you'd
be willing to step up this summer should something happen to a mentor
please say so!

Thanks,
David

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Re: Google Summer of Code 2012 Application

[Federico Brubacher]

Looks amazing David, I'm very interested to apply as a student if we get in
as an Organization.

Best,
Federico

On Wed, Mar 7, 2012 at 4:47 PM, David Nolen dnolen.li...@gmail.com wrote:

 I've made some progress here:


 http://dev.clojure.org/display/community/Google+Summer+of+Code+2012+Application+Questions

 For those with edit right please edit as you see fit and as soon as you
 can, we're running out of time, thanks! :)

 David

 On Wed, Mar 7, 2012 at 1:37 PM, Alexander Yakushev 
 yakushev.a...@gmail.com wrote:

 Great job answering the application questions, David! I was just
 wondering if Steve Yegge could vouch for Clojure since I remember him being
 very excited about the language, so maybe he might say a nice word for
 Clojure participation...

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-- 
Federico Brubacher
@fbru02

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Re: How I can use InteractionEvent in clojure?

[Aaron Cohen]

Unfortunately, I've been unable to get vtk to compile locally.

At this point, it's seeming to me that your issue is more vtk-related
than clojure, though. Can you put a println in the callback to confirm
that it's at least being called?

One question, is it significant that your code is slightly different
from the example here?

(doto coneMapper
      (.SetInputConnection (.GetOutputPort cone)))

Although I'm not sure if it's significant, from reading the example
code, it would be:

 (doto coneMapper
       (.SetInput (.GetOutput cone)))

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Re: What Java classes/objects/methods do you find yourself most often using?

[Jim - FooBar();]

On 06/03/12 17:09, John Gabriele wrote:

While writing Clojure code, what Java classes, objects, and static
methods do you most often find yourself using?


I use java.lang.Math quite a lot...

Jim

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labrepl in eclipse 3.6

[nilesh Shah]

I am a novice at both java and clojure.  I installed the counterclockwise 
eclipse plugin and the labrepl as per 
http://dev.clojure.org/display/doc/Getting+Started+with+Eclipse+and+Counterclockwise
 . 
 After install one of the steps is to 

Enable Clojure Support
   
   - Right-click the labrepl project in Package Explorer and choose 
   Enable/disable Clojure language support



When I do this I get Error while tryiing to toggle clojure language 
support for project labrepl:

Any suggestion as to what this means and how I can proceed to get the lab 
working ?

Thx

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Re: How to escape a space in a keyword?

[Leif]

Unfortunately, the reader does not actually follow this spec, e.g. it will 
happily accept :div#id.cla$$ as a valid keyword.  Some web programming 
clojure[script] libraries use this pseudo-CSS syntax in keywords, so if the 
reader was changed to strictly follow these rules, a lot of web code would 
probably break. 

On Tuesday, March 6, 2012 12:13:20 PM UTC-8, stuart@gmail.com wrote:

 I don't think you're supposed to use spaces in keywords.



 Using spaces in keywords is completely valid, as is using spaces in
 symbols. 


 Legal characters in keywords and symbols are documented at  
 http://clojure.org/reader :
  
 Symbols begin with a non-numeric character and can contain alphanumeric 
 characters and *, +, !, -, _, and ? ... Keywords are like symbols ...

 Stu




On Tuesday, March 6, 2012 12:13:20 PM UTC-8, stuart@gmail.com wrote:

 I don't think you're supposed to use spaces in keywords.



 Using spaces in keywords is completely valid, as is using spaces in
 symbols. 


 Legal characters in keywords and symbols are documented at  
 http://clojure.org/reader :
  
 Symbols begin with a non-numeric character and can contain alphanumeric 
 characters and *, +, !, -, _, and ? ... Keywords are like symbols ...

 Stu





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Can Clojure be as readable as Python or Ruby ?

[Leon Talbot]

If so, how ?

Thanks !

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Re: Can Clojure be as readable as Python or Ruby ?

[Angel Java Lopez]

An old thread:
http://groups.google.com/group/clojure/browse_thread/thread/319a1c77ed718ba/3e4be7484b7cbe38?pli=1


Also, someone proposed instead of
(f a b c)
begin to use
f(a, b, c) or something alike

but I don't have the thread link now

On Wed, Mar 7, 2012 at 2:39 PM, Leon Talbot leontal...@gmail.com wrote:

 If so, how ?

 Thanks !

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Re: Can Clojure be as readable as Python or Ruby ?

[Angel Java Lopez]

Maybe this proposal:
http://grokbase.com/t/gg/clojure/11ctt573jq/list-syntax-sugar-f-x-notation

On Wed, Mar 7, 2012 at 6:09 PM, Angel Java Lopez ajlopez2...@gmail.comwrote:

 An old thread:

 http://groups.google.com/group/clojure/browse_thread/thread/319a1c77ed718ba/3e4be7484b7cbe38?pli=1


 Also, someone proposed instead of
 (f a b c)
 begin to use
 f(a, b, c) or something alike

 but I don't have the thread link now

 On Wed, Mar 7, 2012 at 2:39 PM, Leon Talbot leontal...@gmail.com wrote:

 If so, how ?

 Thanks !

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Re: Can Clojure be as readable as Python or Ruby ?

[Timothy Baldridge]

 If so, how ?


I think Python may be easier for you, but it's not simpler than
Clojure. Simplicity is the strength of Clojure.
http://www.infoq.com/presentations/Simple-Made-Easy
I can learn a new syntax almost overnight (last night I started
writing Dart code for the first time after googling the syntax for 15
min), but the power of macros, immutable data, and laziness are what
really makes Clojure stand out.


Timothy
-- 
“One of the main causes of the fall of the Roman Empire was
that–lacking zero–they had no way to indicate successful termination
of their C programs.”
(Robert Firth)

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Re: Can Clojure be as readable as Python or Ruby ?

[Aaron Cohen]

On Wed, Mar 7, 2012 at 12:39 PM, Leon Talbot leontal...@gmail.com wrote:
 If so, how ?

 Thanks !


Isn't it already?

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Re: Can Clojure be as readable as Python or Ruby ?

[Jeff Heon]

I think readable is in the eye of the beholder.

I've only moderate experience with Clojure, but the following example
from Open Dylan made me realize I really do prefer a concise
representation over what is considered easier to read.
http://opendylan.org/documentation/intro-dylan/why-dylan.html#functional-languages
define method shoe-size (person :: string)
  if (person = Larry)
14
  else
11
  end if
end method;

Versus
http://opendylan.org/documentation/intro-dylan/why-dylan.html#algebraic-infix-syntax
(define (shoe-size person)
  (if (equal? person Joe)
14
11))


Albeit my preference could be different over a different example.
Silly humans 8)

The thing is, if you just keep using Clojure or another Lisp for a
little while, you'll probably get used to it and find it comfortable.

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Re: How to escape a space in a keyword?

[Meikel Brandmeyer]

Hi,

Am 07.03.2012 um 01:11 schrieb Leif:

 Unfortunately, the reader does not actually follow this spec, e.g. it will 
 happily accept :div#id.cla$$ as a valid keyword.  Some web programming 
 clojure[script] libraries use this pseudo-CSS syntax in keywords, so if the 
 reader was changed to strictly follow these rules, a lot of web code would 
 probably break. 

It's the other way around: the reader *does* follow the spec. Feed it a valid 
sequence of characters and you will get a valid keyword. Feed it an invalid 
sequence of characters and you will get an invalid keyword. This is not in 
conflict with the spec. A bad decision to do so instead of bailing out? Maybe. 
Maybe not.

However documenting everywhere that feeding garbage in might result in shit 
coming out has this “things in the mirror might be closer than they appear” 
taste. WTF? The mirror is not the problem. Nor is the car manufacturer to be 
held responsible. If the driver of a car causes an accident, it's her fault. 
*She* is responsible. No one else.

The developers of said libraries obviously didn't live up to their 
responsibility. Either they did not research how the reader works and what 
valid keyword characters are. Then they did not do their job correctly. Or they 
knew how the reader works but knowingly decided to operate it outside defined 
limits. Then they basically gambled that things keep working and that the 
characters will be eventually allowed in future versions of the reader.

In this particular case I would expect the bet to pay off. But if suddenly the 
reader is changed to handle # differently, then all these libraries will break. 
And now guess who is responsible. The reader? No.

Don't pass the buck.

Sincerely
Meikel

PS: I hope Clojure's development mode is not switched to “fait accompli driven.”

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Re: Google Summer of Code 2012 Application

[David Nolen]

Looks like Dan Friedman, William Byrd and the IU Googlers they know might
be getting behind our application as vouchers.

There's no better time to submit proposals or step up to be a mentor than
now :)

David

On Wed, Mar 7, 2012 at 1:47 PM, David Nolen dnolen.li...@gmail.com wrote:

 I've made some progress here:


 http://dev.clojure.org/display/community/Google+Summer+of+Code+2012+Application+Questions

 For those with edit right please edit as you see fit and as soon as you
 can, we're running out of time, thanks! :)

 David

 On Wed, Mar 7, 2012 at 1:37 PM, Alexander Yakushev 
 yakushev.a...@gmail.com wrote:

 Great job answering the application questions, David! I was just
 wondering if Steve Yegge could vouch for Clojure since I remember him being
 very excited about the language, so maybe he might say a nice word for
 Clojure participation...

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Re: Google Summer of Code 2012 Application

[Chris Granger]

When's the official cutoff?

Cheers,
Chris.


On Wed, Mar 7, 2012 at 2:24 PM, David Nolen dnolen.li...@gmail.com wrote:

 Looks like Dan Friedman, William Byrd and the IU Googlers they know might
 be getting behind our application as vouchers.

 There's no better time to submit proposals or step up to be a mentor than
 now :)

 David


 On Wed, Mar 7, 2012 at 1:47 PM, David Nolen dnolen.li...@gmail.comwrote:

 I've made some progress here:


 http://dev.clojure.org/display/community/Google+Summer+of+Code+2012+Application+Questions

 For those with edit right please edit as you see fit and as soon as you
 can, we're running out of time, thanks! :)

 David

 On Wed, Mar 7, 2012 at 1:37 PM, Alexander Yakushev 
 yakushev.a...@gmail.com wrote:

 Great job answering the application questions, David! I was just
 wondering if Steve Yegge could vouch for Clojure since I remember him being
 very excited about the language, so maybe he might say a nice word for
 Clojure participation...

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[ANN] Leiningen 2.0.0-preview1

[Phil Hagelberg]

Hello folks!

I'm proud to announce the release of Leiningen 2.0.0-preview1. While
this isn't a final stable release, it's fairly stable and should be
usable for the majority of projects. This is a near-rewrite and contains
a few backwards-compatibility breaks, but updating should be pretty
painless in most cases thanks to the lein-precate plugin that can
suggest a new 2.x-compatible project.clj file.

Highlights for this release:

* Support profiles for alternate project configurations.
* Replace maven-ant-tasks with Pomegranate library. (Chas Emerick, Nelson 
Morris)
* Complete rewrite of repl task. (Colin Jones, Chas Emerick, Anthony Grimes)
* Rewrite new task. (Anthony Grimes)
* New check task for catching reflection and other issues. (David Santiago)
* Allow partial application of aliases.
* Split out leiningen-core into independent library.

See the full list of user-visible changes:

  https://github.com/technomancy/leiningen/blob/master/NEWS.md

There's a guide covering the upgrade process:

  https://github.com/technomancy/leiningen/wiki/Upgrading

If you are a plugin author, see the newly updated plugin guide,
particularly the section on Upgrading Existing Plugins:

  https://github.com/technomancy/leiningen/blob/master/doc/PLUGINS.md

And we're also launching http://leiningen.org as an introductory page at
this time.

Please give this preview release a try and let us know how it works for you.

-Phil

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Re: Google Summer of Code 2012 Application

[David Nolen]

March 9th!

David

On Wed, Mar 7, 2012 at 5:26 PM, Chris Granger ibdk...@gmail.com wrote:

 When's the official cutoff?

 Cheers,
 Chris.


 On Wed, Mar 7, 2012 at 2:24 PM, David Nolen dnolen.li...@gmail.comwrote:

 Looks like Dan Friedman, William Byrd and the IU Googlers they know might
 be getting behind our application as vouchers.

 There's no better time to submit proposals or step up to be a mentor than
 now :)

 David


 On Wed, Mar 7, 2012 at 1:47 PM, David Nolen dnolen.li...@gmail.comwrote:

 I've made some progress here:


 http://dev.clojure.org/display/community/Google+Summer+of+Code+2012+Application+Questions

 For those with edit right please edit as you see fit and as soon as you
 can, we're running out of time, thanks! :)

 David

 On Wed, Mar 7, 2012 at 1:37 PM, Alexander Yakushev 
 yakushev.a...@gmail.com wrote:

 Great job answering the application questions, David! I was just
 wondering if Steve Yegge could vouch for Clojure since I remember him being
 very excited about the language, so maybe he might say a nice word for
 Clojure participation...

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Re: Can Clojure be as readable as Python or Ruby ?

[James Sofra]

Hi,

I have recently started working in python, I don't find python very 
readable at all compared to clojure.
It is more about familiarity than anything else.

On Thursday, March 8, 2012 4:39:08 AM UTC+11, Leon Talbot wrote:

 If so, how ? 

 Thanks !

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Re: Can Clojure be as readable as Python or Ruby ?

[Alex Baranosky]

If we're going to talk about readability at all, then we need to first
define what attributes make up that which is readable.

What commonly passes for readability is simply a variant of Easy, namely
readable means near to your current body of knowledge.

Is German less readable than English?

I think that the real question that is: if you know Python and Clojure
equally well, then which is easier to read?

Alex

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Re: How I can use InteractionEvent in clojure?

[Antonio Recio]

When I print myCallback I obtain this:
(println myCallback)
user = #example$myCallback example$myCallback@6e1c51b4

I have used this:
(doto coneMapper
   (.SetInput (.GetOutput cone)))
And the applications runs, with not errors in the prompt too, but the 
boxWidget still doesn't work.



On Wednesday, March 7, 2012 9:19:38 PM UTC+1, Aaron Cohen wrote:

 Unfortunately, I've been unable to get vtk to compile locally.

 At this point, it's seeming to me that your issue is more vtk-related
 than clojure, though. Can you put a println in the callback to confirm
 that it's at least being called?

 One question, is it significant that your code is slightly different
 from the example here?

 (doto coneMapper
   (.SetInputConnection (.GetOutputPort cone)))

 Although I'm not sure if it's significant, from reading the example
 code, it would be:

  (doto coneMapper
(.SetInput (.GetOutput cone)))



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Re: How I can use InteractionEvent in clojure?

[Aaron Cohen]

I meant do:

(def myCallback
  (fn []
(println Invoked!)
(let [t (vtk.vtkTransform.)]
(.GetTransform t)
(- boxWidget .GetProp3D (.SetUserTransform t)

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Re: Clojure 1.3 treatment of integers and longs

[Paul Stadig]

On Sunday, October 23, 2011 5:21:52 PM UTC-4, Rich Hickey wrote:

 Hi all,

 This reply is to the thread, not Luc specifically.

 Thanks everyone for your feedback and input.

 I have pushed 3 commits:

 1) Fixes the inconsistency between the hash function used by Clojure maps 
 (was .hashCode) and =. Thanks Paul for the report.

 2) Changes core/hash to return the result of this hashing function. Thus, 
 it returns a different value than does .hashCode for Integers, Shorts, 
 Bytes and Clojure collections. Feedback welcome.

 3) Only due to the first fix, it now becomes possible to box ints to 
 Integers without much grief. This commit implements that for evaluation 
 purposes, and is not a commitment to that policy. Note well that while in 
 the first commit the answer is clear, on this point there is always going 
 to be a tradeoff and there is no 'right' answer. 

 Here are the issues as I see them:

 First, note there is no 'following' of Java semantics as an objective. 
 Java semantics are that Integers are never equal to Longs, and I presume no 
 one wants to go back to that. 

 Second, boxing is a change of type, period. There is no valid complaint 
 that 'you changed my type'. int != Integer either.

 Third, there are 2 scenarios in consuming things you box in Clojure from 
 Java:

 a) You control the Java. In this case, having Clojure make everything 
 uniform (Longs) make things easier for you. There is no heterogeneousness 
 regardless of the source or manipulation of numbers, and can always expect 
 Longs.

 b) You don't control the Java. In this case you must match consuming 
 expectations i.e. conforming to Java promotion, types of generics etc. 
 ***This will *always* require vigilance and explicitness due to arithmetic 
 conversions etc***. Auto promotion is only one part. Note that this is true 
 in Java as well - while type checker may scold you, you still have to 
 cast/coerce on mismatch.
  
 Even with the auto box change, you are only an arithmetic operation away 
 from having the problem again. For instance in the original report, 
 wrapping .getValue with dec generates an interop mismatch again:

 (let [amap {1 (dec (.getValue obj))}] …)

 There is no way we are going to 'fix' that by adopting Java's numeric 
 tower, which is dangerous and requires static types. The bottom line is 
 specific type requirements on the Java side require explicit boxing on 
 order to have correct and non-brittle code.

 The final consideration is collection equality. When Clojure autoboxes to 
 Longs, you get homogeneous collection contents, and thus .equals is still 
 true for the collection on the Java side,  vs random - 'depends on where I 
 got the contents from and what I did with them'. 

 FYI - there are the RT/box functions that box as per Java. These could be 
 exposed in Clojure.

 -
 In short, having autoboxing match Java does not really free you from your 
 responsibility to create specific boxed types when you need them on the 
 Java side. I.e., Clojure can't help you.

 On the flip side, when you are in charge of the Java code, Clojure's being 
 more consistent makes things more consistent on the other side and *does* 
 give you less to do to make sure things work.

 I prefer what we had (auto box to Longs), but I think it matters a 
 somewhat less now with = consistent hashing. If we decide to revert to that 
 we can discuss making auto boxing of short and byte consistent.
 -

Rich,
In Clojure 1.4.0-beta3 ints are boxed as Integers.

Clojure 1.4.0-beta3
user= (map type [(byte 1) (short 1) (int 1) (long 1)])
(java.lang.Byte java.lang.Short java.lang.Integer java.lang.Long)

Based on the above and my conversation with you at the Conj you seemed to 
be pretty convinced that ints should be boxed as Longs. You made a 
temporary commit to box them as Integers 
(https://github.com/clojure/clojure/commit/a2e4d1b4eaa6dad26a1a96b9e9af129a9d10),
 
then Stu Halloway reverted it 
(https://github.com/clojure/clojure/commit/abfa803838a1884d0c5112bc6b876cf33a8a05cc),
 
then he reverted the revert 
(https://github.com/clojure/clojure/commit/798a98bc1b844b0fe08e9309886823cf7ca92604).

Are we still in the temporary period for evaluation purposes? Have you 
changed your mind? If so, I'd be interested to hear why. Should we expect 
this behavior from beta3 to change any time soon?


Paul

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Re: How I can use InteractionEvent in clojure?

[Antonio Recio]

It seems that callback is not called. I have added  (println Testing 
callback) in the definition of myCallback and there is not message in the 
prompt when I run the application.

(def myCallback
  (fn []
(let [t (vtk.vtkTransform.)]
  (.GetTransform t)
  (- boxWidget .GetProp3D (.SetUserTransform t))
  (println Testing callback

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Re: How I can use InteractionEvent in clojure?

[Aaron Cohen]

On Mon, Mar 5, 2012 at 5:50 PM, Antonio Recio amdx6...@gmail.com wrote:
       (.AddObserver interactionEvent myCallback run)

I suspect this is mis-capitalized, it need to be InteractionEvent.

--Aaron

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Re: How to escape a space in a keyword?

[Frank Siebenlist]

Clojure is a young language, and I believe there is little argument that some 
of the interfaces/implementations and associated docs could be improved. You 
can find plenty of examples where functions would throw exceptions for invalid 
input, others return nil in that case, and a number return garbage for garbage. 
Some of this perceived inconsistency could be improved upon, either by 
changing/adding validation code or by adding clarifications to the 
documentation of the functions. 

The symbol function doc consists of only: Returns a Symbol with the given 
namespace and name. Unless you suggest that we all look at the symbol code 
itself before we start using those parameters, it may help to add a little bit 
more text to guide the novice user of the interface such that one knows that 
this particular function doesn't throw exceptions or return nil, but returns 
invalid output for invalid input…  for that suggestion I'm rewarded with a 
condescending …WTF… gender-neutral (?) rant - guess you're truly encouraging 
people on this list to ask questions and suggest solutions/improvements ;-).

My suggestion still stands: add more text to the doc-string of some of the 
functions such that the user has a better understanding of what to expect: no 
validation, nil, exception, expected parameter type, ???. I'd be happy to 
suggest wording.

Another option that may help us to use valid identifiers in our code is to have 
a function like: (clojure.core/valid-name? a-str), which is maintained by core 
(and not by us all writing some regex based on the current specs on a web 
page). We can use it in our code and tests to ensure we're following the 
current specs. If the valid characters are extended in the next clojure 
version, so is the function, and we can automatically conform. I'd be happy to 
provide code.

Sincerely, FrankS.



On Mar 7, 2012, at 2:00 PM, Meikel Brandmeyer wrote:

 Hi,
 
 Am 07.03.2012 um 01:11 schrieb Leif:
 
 Unfortunately, the reader does not actually follow this spec, e.g. it will 
 happily accept :div#id.cla$$ as a valid keyword.  Some web programming 
 clojure[script] libraries use this pseudo-CSS syntax in keywords, so if the 
 reader was changed to strictly follow these rules, a lot of web code would 
 probably break. 
 
 It's the other way around: the reader *does* follow the spec. Feed it a valid 
 sequence of characters and you will get a valid keyword. Feed it an invalid 
 sequence of characters and you will get an invalid keyword. This is not in 
 conflict with the spec. A bad decision to do so instead of bailing out? 
 Maybe. Maybe not.
 
 However documenting everywhere that feeding garbage in might result in shit 
 coming out has this “things in the mirror might be closer than they appear” 
 taste. WTF? The mirror is not the problem. Nor is the car manufacturer to be 
 held responsible. If the driver of a car causes an accident, it's her fault. 
 *She* is responsible. No one else.
 
 The developers of said libraries obviously didn't live up to their 
 responsibility. Either they did not research how the reader works and what 
 valid keyword characters are. Then they did not do their job correctly. Or 
 they knew how the reader works but knowingly decided to operate it outside 
 defined limits. Then they basically gambled that things keep working and that 
 the characters will be eventually allowed in future versions of the reader.
 
 In this particular case I would expect the bet to pay off. But if suddenly 
 the reader is changed to handle # differently, then all these libraries will 
 break. And now guess who is responsible. The reader? No.
 
 Don't pass the buck.
 
 Sincerely
 Meikel
 
 PS: I hope Clojure's development mode is not switched to “fait accompli 
 driven.”
 
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Re: How to escape a space in a keyword?

[Phil Hagelberg]

Frank Siebenlist frank.siebenl...@gmail.com writes:

 My suggestion still stands: add more text to the doc-string of some of
 the functions such that the user has a better understanding of what to
 expect: no validation, nil, exception, expected parameter type, ???.
 I'd be happy to suggest wording.

Agreed. This is only one instance of a number of cases that the user
must hunt around on clojure.org for things that should be available in
docstrings, which is unreasonable for a number of reasons.

 Another option that may help us to use valid identifiers in our code
 is to have a function like: (clojure.core/valid-name? a-str), which is
 maintained by core (and not by us all writing some regex based on the
 current specs on a web page).

If you're just interested in what's round-trippable, that could be done
with this: (apply = ((juxt read-string symbol) symbol-name))

But something more formal wouldn't hurt either.

-Phil

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Re: Can Clojure be as readable as Python or Ruby ?

[Alan Malloy]

On Mar 7, 9:39 am, Leon Talbot leontal...@gmail.com wrote:
 If so, how ?

 Thanks !

[Closed as: Not a real question]

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Re: Can Clojure be as readable as Python or Ruby ?

[Mark Engelberg]

On Wed, Mar 7, 2012 at 3:16 PM, Alex Baranosky 
alexander.barano...@gmail.com wrote:

 I think that the real question that is: if you know Python and Clojure
 equally well, then which is easier to read?

 Alex



I know both equally well (actually, I've logged more hours in my life
coding in Lisp syntax than other syntaxes), and I still consider Python to
be significantly easier to read.

A few specific things that hinder Clojure's readability in my opinion:

* prefix notation for arithmetic operators defies centuries of mathematical
notation conventions and consequently any mathematical formula will be less
readable.

* introducing variables creates new indenting level, making code creep to
the right

* as code creeps to the right, you need to have a lot more newlines (for
example, between each input to a function) to get it to fit on the page.
This lengthens the code block making less fit on a page, and also makes the
code look a lot different than the exact same code would look if it were
appearing in a place that were less indented.

* The convention of using hyphens to separate words is hard to read (since
- looks like the minus operator) and also takes up more width than camel
case, contributing to the problem that you quickly find lines getting too
wide and needing to be broken up.

* loop/recur is significantly less readable than either the corresponding
looping constructs in Python or the named let that Scheme offers,
*especially* when you have some sort of nested looping going on, which is
extraordinarily difficult to read in Clojure.

* cond branches are sometimes written with the test and the answer on the
same line, or when the test gets too long you have to write it with the
test and answer on subsequent lines; this inconsistent formatting can make
it hard to know in long blocks whether you are looking at the test or the
answer

* Interweavings of cond and let (a common pattern) end up ridiculously
indented and hard to read [Grand's flatter cond macro helps with this; I'd
love to see this brought into Clojure core]

* Decades worth of classic algorithms involving imperative manipulation of
arrays look significantly uglier in Clojure, because Clojure intentionally
makes imperative manipulation more difficult.  I have, for fun, converted
many Knuth algorithms to Clojure, and they invariably are far less
scrutable than the original.

* Expression-oriented syntax (along with the indenting cost of using let)
encourages people to pack far too much into one line rather than giving
names to intermediate results.

* DSLs are supposed to bring customized readable notation to many tasks,
but by the time you include namespace prefixes and colons for all the
keywords, DSLs don't really look that good.  I mean, compare Frinj to
Frink.  Frinj's integration into Clojure is cool, but is there anyone who
considers it even half as readable as Frink?  I certainly don't.

* I feel really clever when I condense some complex loop into some sort of
map/filter/reduce using anonymous functions.  And it looks brilliant when I
read my own code that does this.  But when I read someone else's compact
higher-order stuff, it's usually a nightmare to try to interpret what it is
doing.  Python's loops may be verbose, but I always know exactly what I'm
looking at when I read someone else's code.

* And the number 1 problem with all Lisps is that when you look at Lisp
code, it's a sea of sameness.  Function applications, Macros, Control
constructs, bindings, data lookups, etc. all look exactly the same.  You
look at Python code, and you instantly see the control flow of the code,
the assignments, the tests, the results, the loops, the data, the data
lookups, the breaks.  It's organized, but visually distinct.

I write code in Clojure because I find the semantics appealing, and I feel
I can get more done in less time than a language like Python.  Code as
data might be nice for writing macros, but the reality is that it forces
programmers to code in an abstract syntax tree which is more computer
friendly than human friendly.  If I were given the option to *read* a
sample program illustrating some concept in any language of my choice, I
would choose Python over Clojure in a heartbeat.

All one man's opinion, of course, but I wanted to bring it up because I am
someone who has logged many years working in Clojure and related Lisp
languages and I still have the opinion that Python is the most readable
language I have encountered.

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Re: [ANN] Leiningen 2.0.0-preview1

[Phil Hagelberg]

Just found a bug that only manifests when you don't have any profiles
and are running outside a project. It's fixed in git, but if you're
getting an NPE on 2.0.0-preview1 and don't have any profiles defined,
try this as a temporary workaround:

$ mkdir ~/.lein; echo {:user {:plugins []}}  ~/.lein/profiles.clj

-Phil

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clojure on android over CLI

[Rostislav Svoboda]

Hi. I'm trying to run:
java -cp clojure-${VERSION}.jar clojure.main

on an Android phone from bash (using the 'terminal-ide' app) but I
can't make it past the error bellow. I did the jar-to-dex conversion
using:
dx --verbose --dex --output=clojure-${VERSION}.dex.jar
clojure-${VERSION}.jar

for clojure-1.3.0.jar, clojure-1.3.0-slim.jar and even for the clojure
clone for Android Neko Toolkit from Daniel Solano Gómez:
https://github.com/sattvik/clojure.git

Does anyone know what I missed? Thx in advance

Bost


  Now searching: clojure-1.3.0.dex.jar
found
java.lang.ExceptionInInitializerError
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.spartacusrex.spartacuside.external.java.main(java.java:124)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ExceptionInInitializerError
at clojure.main.clinit(main.java:20)
... 4 more
Caused by: java.lang.RuntimeException: java.io.FileNotFoundException:
Could not locate clojure/core__init.class or clojure/core.clj on
classpath:
at clojure.lang.Util.runtimeException(Util.java:165)
at clojure.lang.RT.clinit(RT.java:319)
... 5 more
Caused by: java.io.FileNotFoundException: Could not locate
clojure/core__init.class or clojure/core.clj on classpath:
at clojure.lang.RT.load(RT.java:430)
at clojure.lang.RT.load(RT.java:398)
at clojure.lang.RT.doInit(RT.java:434)
at clojure.lang.RT.clinit(RT.java:316)
... 5 more


In case of the clojure clone for Daniel Solano Gómez:

  Now searching: clojure-1.4.0-master-SNAPSHOT.dex.jar
found
java.lang.ExceptionInInitializerError
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.spartacusrex.spartacuside.external.java.main(java.java:124)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ExceptionInInitializerError
at clojure.main.clinit(main.java:20)
... 4 more
Caused by: java.lang.ExceptionInInitializerError
at java.lang.Class.classForName(Native Method)
at java.lang.Class.forName(Class.java:234)
at java.lang.Class.forName(Class.java:181)
at clojure.lang.RT.clinit(RT.java:235)
... 5 more
Caused by: java.lang.ExceptionInInitializerError
at android.os.Build$VERSION.clinit(Build.java:75)
... 9 more
Caused by: java.lang.UnsatisfiedLinkError: native_get
at android.os.SystemProperties.native_get(Native Method)
at android.os.SystemProperties.get(SystemProperties.java:59)
at android.os.Build.getString(Build.java:216)
at android.os.Build.clinit(Build.java:27)
... 10 more

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Re: How to escape a space in a keyword?

[Justin Steward]

On Thu, Mar 8, 2012 at 9:00 AM, Meikel Brandmeyer m...@kotka.de wrote:
 However documenting everywhere that feeding garbage in might result in shit 
 coming out has this “things in the mirror might be closer than they appear” 
 taste. WTF? The mirror is not the problem. Nor is the car manufacturer to be 
 held responsible. If the driver of a car causes an accident, it's her fault. 
 *She* is responsible. No one else.

If the driver is unaware that what they see in the mirror is
distorted, the driver will assume it is not. A driver who has been
supplied incomplete information about the operation of their vehicle
can not reasonably be held fully responsible, which is why we have so
many warning labels.

Documentation for programming languages should take the same approach.
If any input other than what is specified will lead to undefined
results, that needs to be documented. Otherwise, someone will feed in
invalid input, get what looks like valid output, and assume that the
documentation is out of date, incomplete, or something equally inane,
and continue to misuse the feature. You can never underestimate the
power of ignorance, no matter a person's creed, intelligence,
lifestyle, or profession. If invalid input will not throw an error
immediately, then it DOES need to be documented that invalid input
will result in undefined output.

~Justin

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Re: Can Clojure be as readable as Python or Ruby ?

[Joachim De Beule]

On Mar 7, 6:39 pm, Leon Talbot leontal...@gmail.com wrote:
 If so, how ?

 Thanks !

Please define readable.

Thanks!

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Re: Can Clojure be as readable as Python or Ruby ?

[Mark Engelberg]

On Wed, Mar 7, 2012 at 3:12 PM, Joachim De Beule joachim.de.be...@gmail.com
 wrote:

 Please define readable.

 Thanks!


Readable is a measure of how readily apparent the meaning of a program is
from looking at it.

If you wanted to measure this objectively, one possible way to do this
would be to time how long it takes a group of programmers to read and
understand a well-crafted program to perform some complex algorithm.  Let's
assume that the programmers are all competent in the language being
measured.  There are other things you might also measure: you could quiz
them to determine if they really understand it as well as they think they
do, you could ask them to modify the code, you could ask them to self-rate
their subjective sense of how easy it was to understand the program.

Tim Daly has opined several times that it would be nice if researchers
would do something like this for literate programming, for example.  It
would be useful to know for sure whether programs in literate form are more
readable than ordinary self-documenting code.

We tend to think of readability as a fairly subjective thing, and it is
subjective to the extent that for most of us, the only measure that matters
is how long we personally feel it takes us to understand code written in a
given language, and how much effort we have to expend to gain that
understanding.  But certainly it is a quantifiable concept, and it is
theoretically possible to compare languages, code coloring schemes,
documentation styles, pop-up support, and all other aspects of code
readability in an objective way.

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[ANN] clojure-py 0.1.0 Clojure on Python

[Timothy Baldridge]

The Clojure-Py team is happy to announce the release of Clojure-Py 0.1.0.

https://github.com/halgari/clojure-py

Clojure-Py is an implementation of Clojure running atop the Python VM.
As it currently stands, we have translated over 235 functions from
clojure.core. This is not a clojure interpreter in python; the
Clojure-Py compiler compiles clojure code directly to python code.
Clojure-py functions are python functions. Clojure-py types are python
types, Clojure-py name spaces are python modules.

Please feel free to browse the examples at
https://github.com/halgari/clojure-py/tree/master/examples to get an
idea of what Clojure-Py can currently accomplish.

Version 0.1.0 should be considered alpha and proof of concept.
That being said, if you stick to the afore mentioned 235 functions,
and python interop, the implementation is very usable and so far quite
stable.

The package is released via the Python Package index so you can simply type

easy_install clojure-py
clojurepy

To install and startup the repl. Python 2.6, 2.7 and PyPy are all
supported. Please check out this release and send us your feedback via
Github.
---

Upcoming in version 0.2.0:

Support for bindings
defprotocol and defmulti
defrecord
full support for pr-str

---

Thank you for all the interest we've received from the Clojure and
Python communities. We look forward to seeing this project grow.

Timothy Baldridge (halgari)

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Clojurescript: named/numbered releases?

[kovas boguta]

It's great to see the steady activity on the clojurescript github page.

However I'm not totally comfortable developing against the master branch.

As it stands now, if I change development environments, or deploy on a
new machine, the master branch may have moved.

I could choose an arbitrary commit as my stable reference point,  and
periodically make a judgement call about upgrading to a new arbitrary
commit, but thats not easy for someone not involved in the internals.

I gather this is still pre-1.0 , but it would still be nice to have
some incremental version numbers to rationalize things.

thanks for listening.

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Re: How I can use InteractionEvent in clojure?

[Antonio Recio]

You are right. I have capitalized InteractionEvent and now callback it is 
called and it prints invoke.

The application runs but the boxWidget still doesn't work, and I obtain an 
error message:
Exception in thread main java.lang.IllegalArgumentException: No matching 
field found: GetTransform for class vtk.vtkTransform
at clojure.lang.Reflector.getInstanceField(Reflector.java:285)
at 
clojure.lang.Reflector.invokeNoArgInstanceMember(Reflector.java:314)
at example$myCallback.invoke(cone.clj:15)
at clojure.lang.AFn.run(AFn.java:24)
at vtk.vtkRenderWindowInteractor.Start_5(Native Method)
at 
vtk.vtkRenderWindowInteractor.Start(vtkRenderWindowInteractor.java:32)
at example$main.invoke(cone.clj:54)
at example$eval21.invoke(cone.clj:58)
at clojure.lang.Compiler.eval(Compiler.java:6488)
at clojure.lang.Compiler.load(Compiler.java:6929)
at clojure.lang.Compiler.loadFile(Compiler.java:6889)
at clojure.main$load_script.invoke(main.clj:283)
at clojure.main$script_opt.invoke(main.clj:343)
at clojure.main$main.doInvoke(main.clj:427)
at clojure.lang.RestFn.invoke(RestFn.java:408)
at clojure.lang.Var.invoke(Var.java:415)
at clojure.lang.AFn.applyToHelper(AFn.java:161)
at clojure.lang.Var.applyTo(Var.java:532)
at clojure.main.main(main.java:37)



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Re: clojure-py 0.1.0 Clojure on Python

[Shantanu Kumar]

Congrat's on the release! I am getting the following error on my
Macbook (running 64-bit Lion, Python 2.7.1) when trying to run sudo
easy_install clojure-py:

Searching for clojure-py
Reading http://pypi.python.org/simple/clojure-py/
Reading https://github.com/halgari/clojure-py
Best match: clojure-py 0.1.0
Downloading 
http://pypi.python.org/packages/source/c/clojure_py/clojure_py-0.1.0.tar.gz#md5=794da1e8031e2d4f3fbc6484ed51c172
Processing clojure_py-0.1.0.tar.gz
Running clojure_py-0.1.0/setup.py -q bdist_egg --dist-dir /tmp/
easy_install-feUpDQ/clojure_py-0.1.0/egg-dist-tmp-78bqof
Traceback (most recent call last):
  File /usr/bin/easy_install-2.7, line 10, in module
load_entry_point('setuptools==0.6c12dev-r85381',
'console_scripts', 'easy_install')()
  File /System/Library/Frameworks/Python.framework/Versions/2.7/
Extras/lib/python/setuptools/command/easy_install.py, line 1712, in
main
with_ei_usage(lambda:
  File /System/Library/Frameworks/Python.framework/Versions/2.7/
Extras/lib/python/setuptools/command/easy_install.py, line 1700, in
with_ei_usage
return f()
  File /System/Library/Frameworks/Python.framework/Versions/2.7/
Extras/lib/python/setuptools/command/easy_install.py, line 1716, in
lambda
distclass=DistributionWithoutHelpCommands, **kw
  File /System/Library/Frameworks/Python.framework/Versions/2.7/lib/
python2.7/distutils/core.py, line 152, in setup
dist.run_commands()
  File /System/Library/Frameworks/Python.framework/Versions/2.7/lib/
python2.7/distutils/dist.py, line 953, in run_commands
self.run_command(cmd)
  File /System/Library/Frameworks/Python.framework/Versions/2.7/lib/
python2.7/distutils/dist.py, line 972, in run_command
cmd_obj.run()
  File /System/Library/Frameworks/Python.framework/Versions/2.7/
Extras/lib/python/setuptools/command/easy_install.py, line 211, in
run
self.easy_install(spec, not self.no_deps)
  File /System/Library/Frameworks/Python.framework/Versions/2.7/
Extras/lib/python/setuptools/command/easy_install.py, line 446, in
easy_install
return self.install_item(spec, dist.location, tmpdir, deps)
  File /System/Library/Frameworks/Python.framework/Versions/2.7/
Extras/lib/python/setuptools/command/easy_install.py, line 476, in
install_item
dists = self.install_eggs(spec, download, tmpdir)
  File /System/Library/Frameworks/Python.framework/Versions/2.7/
Extras/lib/python/setuptools/command/easy_install.py, line 655, in
install_eggs
return self.build_and_install(setup_script, setup_base)
  File /System/Library/Frameworks/Python.framework/Versions/2.7/
Extras/lib/python/setuptools/command/easy_install.py, line 930, in
build_and_install
self.run_setup(setup_script, setup_base, args)
  File /System/Library/Frameworks/Python.framework/Versions/2.7/
Extras/lib/python/setuptools/command/easy_install.py, line 919, in
run_setup
run_setup(setup_script, args)
  File /System/Library/Frameworks/Python.framework/Versions/2.7/
Extras/lib/python/setuptools/sandbox.py, line 62, in run_setup
lambda: execfile(
  File /System/Library/Frameworks/Python.framework/Versions/2.7/
Extras/lib/python/setuptools/sandbox.py, line 105, in run
return func()
  File /System/Library/Frameworks/Python.framework/Versions/2.7/
Extras/lib/python/setuptools/sandbox.py, line 64, in lambda
{'__file__':setup_script, '__name__':'__main__'}
  File setup.py, line 10, in module
  File /tmp/easy_install-feUpDQ/clojure_py-0.1.0/clojure/
__init__.py, line 2, in module
  File /tmp/easy_install-feUpDQ/clojure_py-0.1.0/clojure/main.py,
line 104, in module
  File /tmp/easy_install-feUpDQ/clojure_py-0.1.0/clojure/main.py,
line 48, in import_hook
ImportError: module clojure.core not found, looked in ['.', '/tmp/
easy_install-feUpDQ/clojure_py-0.1.0', '/usr/bin', '/Library/Python/
2.7/site-packages/mercurial-2.0-py2.7-macosx-10.7-intel.egg', '/
Library/Python/2.7/site-packages/hg_git-0.3.2-py2.7.egg', '/Library/
Python/2.7/site-packages/dulwich-0.8.3-py2.7-macosx-10.7-intel.egg', '/
Library/Python/2.7/site-packages/Pygments-1.4-py2.7.egg', '/System/
Library/Frameworks/Python.framework/Versions/2.7/lib/python27.zip', '/
System/Library/Frameworks/Python.framework/Versions/2.7/lib/
python2.7', '/System/Library/Frameworks/Python.framework/Versions/2.7/
lib/python2.7/plat-darwin', '/System/Library/Frameworks/
Python.framework/Versions/2.7/lib/python2.7/plat-mac', '/System/
Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-
mac/lib-scriptpackages', '/System/Library/Frameworks/Python.framework/
Versions/2.7/Extras/lib/python', '/System/Library/Frameworks/
Python.framework/Versions/2.7/lib/python2.7/lib-tk', '/System/Library/
Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-old', '/
System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/
lib-dynload', '/System/Library/Frameworks/Python.framework/Versions/
2.7/Extras/lib/python/PyObjC', '/Library/Python/2.7/site-packages', '/
tmp/easy_install-feUpDQ/clojure_py-0.1.0/clojure']

Re: How I can use InteractionEvent in clojure?

[Mark Rathwell]

You are trying to call method GetTransform on an instance of
vtk.vtkTransform, and this method does not exist (you are probably
wanting to call that method on boxWidget, not t).

On Thu, Mar 8, 2012 at 12:32 AM, Antonio Recio amdx6...@gmail.com wrote:
 You are right. I have capitalized InteractionEvent and now callback it is
 called and it prints invoke.

 The application runs but the boxWidget still doesn't work, and I obtain an
 error message:
 Exception in thread main java.lang.IllegalArgumentException: No matching
 field found: GetTransform for class vtk.vtkTransform
         at clojure.lang.Reflector.getInstanceField(Reflector.java:285)
         at
 clojure.lang.Reflector.invokeNoArgInstanceMember(Reflector.java:314)
         at example$myCallback.invoke(cone.clj:15)
         at clojure.lang.AFn.run(AFn.java:24)
         at vtk.vtkRenderWindowInteractor.Start_5(Native Method)
         at
 vtk.vtkRenderWindowInteractor.Start(vtkRenderWindowInteractor.java:32)
         at example$main.invoke(cone.clj:54)
         at example$eval21.invoke(cone.clj:58)
         at clojure.lang.Compiler.eval(Compiler.java:6488)
         at clojure.lang.Compiler.load(Compiler.java:6929)
         at clojure.lang.Compiler.loadFile(Compiler.java:6889)
         at clojure.main$load_script.invoke(main.clj:283)
         at clojure.main$script_opt.invoke(main.clj:343)
         at clojure.main$main.doInvoke(main.clj:427)
         at clojure.lang.RestFn.invoke(RestFn.java:408)
         at clojure.lang.Var.invoke(Var.java:415)
         at clojure.lang.AFn.applyToHelper(AFn.java:161)
         at clojure.lang.Var.applyTo(Var.java:532)
         at clojure.main.main(main.java:37)

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Re: Can Clojure be as readable as Python or Ruby ?

[Mark Engelberg]

Going back to the original poster's question, I think if I could make only
one change to Clojure's syntax to improve readability, I'd take a page from
other functional languages like F# and Racket and add a way to bind local
variables that doesn't indent.  So, for example,

(let x 2)
code

would behave like the current:
(let [x 2]
   code)

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Re: Can Clojure be as readable as Python or Ruby ?

[Andy Fingerhut]

You might have a difficult time getting other Clojure coders to adopt the 
practice in their code, but would this be almost as good?

(let [x 2]
code)

Achieving that would be as simple as hand-indenting it that way, or adjusting 
the auto-indenter of your favorite text editor to do it that way.  A couple of 
minutes of perusing clojure-mode.el for emacs didn't make it obvious to me how 
to do that, but I suspect it wouldn't be difficult.

Andy

On Mar 7, 2012, at 10:22 PM, Mark Engelberg wrote:

 Going back to the original poster's question, I think if I could make only 
 one change to Clojure's syntax to improve readability, I'd take a page from 
 other functional languages like F# and Racket and add a way to bind local 
 variables that doesn't indent.  So, for example,
 
 (let x 2)
 code
 
 would behave like the current:
 (let [x 2]
code)
 
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Re: Can Clojure be as readable as Python or Ruby ?

[Mark Engelberg]

On Wed, Mar 7, 2012 at 10:43 PM, Andy Fingerhut andy.finger...@gmail.comwrote:

 You might have a difficult time getting other Clojure coders to adopt the
 practice in their code, but would this be almost as good?

 (let [x 2]
 code)

 Achieving that would be as simple as hand-indenting it that way, or
 adjusting the auto-indenter of your favorite text editor to do it that way.
  A couple of minutes of perusing clojure-mode.el for emacs didn't make it
 obvious to me how to do that, but I suspect it wouldn't be difficult.

 Andy


It's an interesting question as to how much of my psychological objection
to let is the added nesting versus the physical indenting.  I agree it
would be a worthwhile experiment to adjust the auto-indenter for a while
and see how it feels.

In the meantime, I *strongly urge* everyone to check out Grand's flatter
cond macro:
https://github.com/cgrand/parsley/blob/master/src/net/cgrand/parsley/util.clj

It lets you insert lets in the middle of cond expressions (like you can
currently do with for) like:
(cond
   (pos? x) 2
   :let [y (* x x)]
( y 20) 4))

This totally transformed my coding style and improved the readability of my
code substantially.  Highly recommended.  Since it is backwards compatible,
I very much wish it were part of the core, and see no reason that it
couldn't be.

--Mark

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Re: Can Clojure be as readable as Python or Ruby ?

[Sean Corfield]

On Wed, Mar 7, 2012 at 5:10 PM, Mark Engelberg mark.engelb...@gmail.com wrote:
 * introducing variables creates new indenting level, making code creep to
 the right

Mitigated by breaking functions into sub-functions (which is good
practice anyway).

 * as code creeps to the right, you need to have a lot more newlines

Then your code is too deeply nested and should be broken into
sub-functions. That's standard best practice across all languages.

 * The convention of using hyphens to separate words is hard to read

I disagree. I find camelCase far harder to read than hyphenated-names.

 * loop/recur is significantly less readable

I don't think it's significantly less readable but I do agree that
recur is a bit of a wart.

 * cond branches are sometimes written with the test and the answer on the
 same line, or when the test gets too long you have to write it with the test
 and answer on subsequent lines; this inconsistent formatting can make it
 hard to know in long blocks whether you are looking at the test or the
 answer

Don't write long blocks. Don't write complex conditions. Introduction
more sub-functions.

 * Interweavings of cond and let (a common pattern) end up ridiculously
 indented and hard to read

See above (and I don't agree it's a common pattern... perhaps an
anti-pattern?).

 * Decades worth of classic algorithms involving imperative manipulation of
 arrays look significantly uglier in Clojure

Yet many algorithms are significantly cleaner in a pure functional style...

 * Expression-oriented syntax (along with the indenting cost of using let)
 encourages people to pack far too much into one line rather than giving
 names to intermediate results.

Again, poor style. Break things into sub-functions.

 * DSLs are supposed to bring customized readable notation to many tasks, but
 by the time you include namespace prefixes and colons for all the keywords,
 DSLs don't really look that good.

Then those DSLs are not achieving their design goals. DSLs are a good
use case for :use or :require/:refer.

 * ... But when I read someone else's compact
 higher-order stuff, it's usually a nightmare to try to interpret what it is
 doing.

Really? I find the compaction outweighs the effort involved - as long
as the code is modular enough (see comments above).

 * And the number 1 problem with all Lisps is that when you look at Lisp
 code, it's a sea of sameness.  Function applications, Macros, Control
 constructs, bindings, data lookups, etc. all look exactly the same.

I actually find that to be a plus - there's no distracting variance
that artificially makes things different that don't need to be.

Syntax is very subjective. It's really good to here your pro-Python
thoughts tho'...
-- 
Sean A Corfield -- (904) 302-SEAN
An Architect's View -- http://corfield.org/
World Singles, LLC. -- http://worldsingles.com/

Perfection is the enemy of the good.
-- Gustave Flaubert, French realist novelist (1821-1880)

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Re: Leiningen 2.0.0-preview1

[C. Arel]

The clojure community is thankful!

On Mar 7, 11:28 pm, Phil Hagelberg p...@hagelb.org wrote:
 Hello folks!

 I'm proud to announce the release of Leiningen 2.0.0-preview1. While
 this isn't a final stable release, it's fairly stable and should be
 usable for the majority of projects. This is a near-rewrite and contains
 a few backwards-compatibility breaks, but updating should be pretty
 painless in most cases thanks to the lein-precate plugin that can
 suggest a new 2.x-compatible project.clj file.

 Highlights for this release:

 * Support profiles for alternate project configurations.
 * Replace maven-ant-tasks with Pomegranate library. (Chas Emerick, Nelson 
 Morris)
 * Complete rewrite of repl task. (Colin Jones, Chas Emerick, Anthony Grimes)
 * Rewrite new task. (Anthony Grimes)
 * New check task for catching reflection and other issues. (David Santiago)
 * Allow partial application of aliases.
 * Split out leiningen-core into independent library.

 See the full list of user-visible changes:

  https://github.com/technomancy/leiningen/blob/master/NEWS.md

 There's a guide covering the upgrade process:

  https://github.com/technomancy/leiningen/wiki/Upgrading

 If you are a plugin author, see the newly updated plugin guide,
 particularly the section on Upgrading Existing Plugins:

  https://github.com/technomancy/leiningen/blob/master/doc/PLUGINS.md

 And we're also launchinghttp://leiningen.orgas an introductory page at
 this time.

 Please give this preview release a try and let us know how it works for you.

 -Phil

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