Comments on: Implicits for the Fearless http://blog.tmorris.net/implicits-for-the-fearless/ The weblog of Tony Morris Tue, 06 Jan 2009 22:33:48 +0000 http://wordpress.org/?v=2.6 By: Implicits for the Masses | Desk Checked http://blog.tmorris.net/implicits-for-the-fearless/#comment-18807 Implicits for the Masses | Desk Checked Wed, 08 Oct 2008 10:46:47 +0000 http://blog.tmorris.net/implicits-for-the-fearless/#comment-18807 [...] just finished reading Tony Morris’s blog post on Scala implicits and saw the following comment: To me, implicits look a lot like global variables, which is why I [...] [...] just finished reading Tony Morris’s blog post on Scala implicits and saw the following comment: To me, implicits look a lot like global variables, which is why I [...]

]]> By: Tony Morris http://blog.tmorris.net/implicits-for-the-fearless/#comment-2384 Tony Morris Sat, 05 Jul 2008 22:12:36 +0000 http://blog.tmorris.net/implicits-for-the-fearless/#comment-2384 Thanks anon for pointing that out. I should have noted in the post that <em>Scala import statements can appear anywhere in a source file</em>. Thanks anon for pointing that out. I should have noted in the post that Scala import statements can appear anywhere in a source file.

]]> By: anon http://blog.tmorris.net/implicits-for-the-fearless/#comment-2383 anon Sat, 05 Jul 2008 22:03:06 +0000 http://blog.tmorris.net/implicits-for-the-fearless/#comment-2383 Just to clarify, as only the term "lesser scoped" was used, implicits have whatever scope you want them to have. You can have them retricted to a single block if desired (for example an nested function), scala imports only apply to a specific scope, implicits are no different. Of course you can also scope them across an entire compilable unit (like in Java) but thats still very far from a global variable. Just to clarify, as only the term “lesser scoped” was used, implicits have whatever scope you want them to have.

You can have them retricted to a single block if desired (for example an nested function), scala imports only apply to a specific scope, implicits are no different.

Of course you can also scope them across an entire compilable unit (like in Java) but thats still very far from a global variable.

]]> By: Tony Morris http://blog.tmorris.net/implicits-for-the-fearless/#comment-2382 Tony Morris Sat, 05 Jul 2008 06:19:51 +0000 http://blog.tmorris.net/implicits-for-the-fearless/#comment-2382 Sean, Maybe this will help http://www.vector-seven.com/2008/07/05/implicits-for-the-masses/ Sean,
Maybe this will help
http://www.vector-seven.com/2008/07/05/implicits-for-the-masses/

]]> By: Tony Morris http://blog.tmorris.net/implicits-for-the-fearless/#comment-2381 Tony Morris Sat, 05 Jul 2008 06:12:50 +0000 http://blog.tmorris.net/implicits-for-the-fearless/#comment-2381 Sean, I'm happy for you to go on your way with Java, but I'm not sure what else to do to address your concerns, which can be split into 2: 1) Implicits "act" like global variables (and so is problematic). 2) Implicits "feel" like global variables. I cannot address 2) and I addressed 1) by pointing out that the premise is flawed; they do not act like global variables at all; therefore, the conclusion is not necessarily true. Enjoy Java :) Sean,
I’m happy for you to go on your way with Java, but I’m not sure what else to do to address your concerns, which can be split into 2:

1) Implicits “act” like global variables (and so is problematic).
2) Implicits “feel” like global variables.

I cannot address 2) and I addressed 1) by pointing out that the premise is flawed; they do not act like global variables at all; therefore, the conclusion is not necessarily true.

Enjoy Java :)

]]> By: Sean Cobb http://blog.tmorris.net/implicits-for-the-fearless/#comment-2380 Sean Cobb Sat, 05 Jul 2008 05:59:33 +0000 http://blog.tmorris.net/implicits-for-the-fearless/#comment-2380 Actually, you are doing a remarkable job at writing three entire paragraphs without addressing the concern that I'm expressing. Back to Java, thanks for your time. Actually, you are doing a remarkable job at writing three entire paragraphs without addressing the concern that I’m expressing.

Back to Java, thanks for your time.

]]> By: Tony Morris http://blog.tmorris.net/implicits-for-the-fearless/#comment-2379 Tony Morris Sat, 05 Jul 2008 05:43:14 +0000 http://blog.tmorris.net/implicits-for-the-fearless/#comment-2379 Hi Sean, I am clear on your intended description, however, what you gave is arguably not global ("global" on its own is a misnomer), and is definitely not variable. It is not variable because you have used the Scala <code>val</code> keyword which implies lack of mutation, side-effect or "varying". The use of the term 'global' requires the definition of a universe of discourse to have a meaning. Most importantly, it is the "variable" part of "global variable" that is the true problem in programming. Indeed, <am>any</em> variable is problematic (I am a strong supporter of the arguments put forward by Erik Meijer including and especially this one). A "global variable" typically has a wide domain and so wreaks greater havoc than a lesser-scoped variable which attracts criticism. So, unlike you who has a contention with global variables, I have a problem with <em>any</em> variable (note, this does not mean I never use them; I just acknowledge the far-reaching implications). However, in this case, since there are no variables, the "dislike" (I quote because I am not fond of using emotional terms to describe such artifacts) is ill-founded. A certain type of discipline in programming completely eliminates the argument presented by cases of sloppy code. I tried to address this in the post without getting too distracted from the more interesting and deeper discussion. Hi Sean,
I am clear on your intended description, however, what you gave is arguably not global (”global” on its own is a misnomer), and is definitely not variable. It is not variable because you have used the Scala val keyword which implies lack of mutation, side-effect or “varying”. The use of the term ‘global’ requires the definition of a universe of discourse to have a meaning.

Most importantly, it is the “variable” part of “global variable” that is the true problem in programming. Indeed, any variable is problematic (I am a strong supporter of the arguments put forward by Erik Meijer including and especially this one). A “global variable” typically has a wide domain and so wreaks greater havoc than a lesser-scoped variable which attracts criticism. So, unlike you who has a contention with global variables, I have a problem with any variable (note, this does not mean I never use them; I just acknowledge the far-reaching implications). However, in this case, since there are no variables, the “dislike” (I quote because I am not fond of using emotional terms to describe such artifacts) is ill-founded.

A certain type of discipline in programming completely eliminates the argument presented by cases of sloppy code. I tried to address this in the post without getting too distracted from the more interesting and deeper discussion.

]]> By: Sean Cobb http://blog.tmorris.net/implicits-for-the-fearless/#comment-2378 Sean Cobb Sat, 05 Jul 2008 05:24:51 +0000 http://blog.tmorris.net/implicits-for-the-fearless/#comment-2378 Hence me using "like". They act and feel just the same to a lot of programmers. For example: scala&gt; def speakImplicitly (implicit greeting : String) = println(greeting) speakImplicitly: (implicit String)Unit scala&gt; speakImplicitly("Goodbye world") Goodbye world scala&gt; speakImplicitly :6: error: no implicit argument matching parameter type String was foud. scala&gt; implicit val hello = "Hello world" hello: java.lang.String = Hello world scala&gt; speakImplicitly Hello world It certainly looks like this method received its parameter from a global variable. Clearer, now? Hence me using “like”. They act and feel just the same to a lot of programmers. For example:

scala&gt; def speakImplicitly (implicit greeting : String) = println(greeting)
speakImplicitly: (implicit String)Unit

scala&gt; speakImplicitly(”Goodbye world”)
Goodbye world

scala&gt; speakImplicitly
:6: error: no implicit argument matching parameter type String was foud.

scala&gt; implicit val hello = “Hello world”
hello: java.lang.String = Hello world

scala&gt; speakImplicitly
Hello world

It certainly looks like this method received its parameter from a global variable.

Clearer, now?

]]> By: Tony Morris http://blog.tmorris.net/implicits-for-the-fearless/#comment-2377 Tony Morris Sat, 05 Jul 2008 04:57:05 +0000 http://blog.tmorris.net/implicits-for-the-fearless/#comment-2377 Importantly, implicits are not variable, nor are they global. I'm not sure what else to say :) Importantly, implicits are not variable, nor are they global. I’m not sure what else to say :)

]]> By: Sean Cobb http://blog.tmorris.net/implicits-for-the-fearless/#comment-2376 Sean Cobb Sat, 05 Jul 2008 04:24:32 +0000 http://blog.tmorris.net/implicits-for-the-fearless/#comment-2376 To me, implicits look a lot like global variables, which is why I don't like them. Or maybe I missed something? To me, implicits look a lot like global variables, which is why I don’t like them.

Or maybe I missed something?

]]>