6 ms·

Emacs 24.4 RC 1

153 points by Xyzodiac 12y ago

benaiah 12y ago
The current plan is to release on Monday.
webkike 12y ago
This release has so many incredible new features. Great job Emacs team!
viksit 12y ago
As someone who uses emacs purely for clojure/lisp and vim for everything else, the biggest feature for me is the fact that this will be the first version of emacs to support menus in terminal mode. So for all the commands you don't remember, a menu is now a click or F10 away. To quote, "Emacs now supports menus on text-mode terminals. If the terminal supports a mouse, clicking on the menu bar, or on sensitive portions of the mode line or header line, will drop down the menu defined at that position." More at: http://www.masteringemacs.org/article/whats-new-in-emacs-24-4 http://www.masteringemacs.org/article/whats-new-in-emacs-24-...
- rezistik 12y ago
  As a dev who's always used Sublime/Atom and sometimes Vim, what's the benefit of Emacs for Lisp?
  - wglb 12y ago
    Slime
  - viksit 12y ago
    There's quite a lot of technology that allows you to write lisp/clojure very well in emacs. Some that come to mind, - Swank/Slime (Lisp inferior modes) that allow you to write lisp, evaluate within the editor, see your results in a buffer. Offer auto complete, refactoring, debugging et al. The more recent nrepl and cider modes for Clojure build on top of slime/swank and offer extremely great tools to write code as well. If you ever wanted to have the REPL running on the side and have great interop between code in a file and the REPL - these modes are great. Imagine their power when you can connect into a running webserver and debug on the fly from within your editor. - A lot of original emacs plugins like paredit have now been ported to other platforms like Sublime. Also, emacs itself is written in lisp, which makes it a first class language it supports at its very core.
    - Havvy 12y ago
      Each lisp varies dramatically in its semantics. Just because emacs is written in e-lisp does not mean it has first class language support for every other lisp. Would you say that vim has first class support for every language with block & statement based languages?
      - viksit 12y ago
        Agree with your high level point. Mine isn't that because it's written in e-lisp, emacs supports every other lisp. The fact that it's written in e-lisp makes it very extensible, and some standard things like C-x C-e to evaluate forms et al, which were originally developed for and are the standard for e-lisp, have been adopted for all other lisp modes as well. The very fact that the editor is written in a lisp makes it expose useful functionality this is useful in other lisp contexts.
  - craigching 12y ago
    I can speak about Clojure support for Emacs a bit, but I don't know how much of this Sublime or Atom can do. I like the cider+nrepl workflow myself. You can edit your code, reevaluate it, and test it without having to restart your JVM. As you can imagine, this really speeds up development. Also, though I haven't quite grokked all the barfing and slurping yet, paredit has really become a huge part of my code writing and editing in Emacs for Clojure code. I am on the cusp of getting barfing and slurping working for me now ;)
  - BostonEnginerd 12y ago
    Emacs is pretty much a built in REPL primarily written in Lisp.
  - malisper 12y ago
    Slime is really amazing. It provides tons of features of which here are a few (these work with Common Lisp, I have no clue if they work with Clojure). Inspector[0]: You can click on objects to "inspect" their values. This includes hash-tables, arrays, and closures. In addition you can execute arbitrary code on these objects at any time, even while a program is running. Trace Dialog[1]: Most Lisp implementations already provide a way to trace procedures. Tracing normally consists of printing the input and the output as each traced procedure is called. Slime provides something much more powerful. Slime's Trace Dialog is similar to trace in that it creates a buffer of the input and output, but instead it is provided in a tree menu format. In addition it is possible to inspect all of the values in the Trace Dialog with the inspector. Debugger[2]: When an error is thrown in a program, a window pops up which provides several things. You can click on a stack frame to see all of the variables in that frame and then inspect those variables with the inspector. You are also provided with a list of restarts[3]. In addition, you can return a value from a given stack frame, or retry a procedure call on the stack frame (you may have modified the definitions of some procedures before you did this), and have the program continue as if nothing had ever happened. There are also many other features, such as the ability to macroexpand code by clicking on it, to look up every procedure which calls a given procedure, to look up every place in which a given variable is set, and many other awesome features. [0] http://common-lisp.net/project/slime/doc/html/Inspector.html http://common-lisp.net/project/slime/doc/html/Inspector.html [1] http://common-lisp.net/project/slime/doc/html/SLIME-Trace-Dialog.html http://common-lisp.net/project/slime/doc/html/SLIME-Trace-Di... [2] http://common-lisp.net/project/slime/doc/html/Debugger.html#Debugger http://common-lisp.net/project/slime/doc/html/Debugger.html#... [3] http://en.wikibooks.org/wiki/Common_Lisp/Advanced_topics/Condition_System#Restarts http://en.wikibooks.org/wiki/Common_Lisp/Advanced_topics/Con...
    - logicchains 12y ago
      That actually sounds a lot like Smalltalk.
      - malkia 12y ago
        Also the editor does not crash if the (lisp) environment becomes unstable (hangs, crashes, etc.) - Such things rarely happen, but they might - for example in Lispworks (which has emacs-like IDE (very nice) but runs the lisp threads in the same process as the editor).
  - TeMPOraL 12y ago
    Aside from all the other reasons other people already listed, there is a one fundamental benefit. Emacs is not just an editor, it's a Lisp runtime with text-editing functionality bolted on top. Lisp is natural for Emacs at all levels of complexity - from the fact that it's easy to work with Lisp code using Lisp to the Emacs community, composed in a big part of Lispers. Lisp just fits Emacs.
- kstrauser 12y ago
  Emacs has had console menus for years. The difference is that they're now clickable, not keyboard-only.
  - viksit 12y ago
    Right - but the fact that they behave more like a window manager menu than ever before - as in, they drop down et al.
- linuxfan 12y ago
  Just curious. How did you manage to use both emacs and vim? I've seen that people accustomed to one editor are usually averse to using the other.
  - inclemnet 12y ago
    > I've seen that people accustomed to one editor are usually averse to using the other. I think this is more a meme than necessarily a reality - you'll tend to see a lot more comments online from people who think the old joke is funny or who want to validate their own choice than from people who don't care or have tried both without such strong feelings. In reality, there's really no barrier to 'manage' to use both emacs and vim. If anything, since they're both powerful and configurable programs whose best configuration is personal and some way from the default, it probably is harder to construct your own perfect config in both than for simpler alternatives like web browsers - I guess this may lead to a practical aversion. Personally, I think vim's modal editing is superb but generally prefer the behaviour of emacs' modes and client model, so I use emacs with evil-mode but have no problem using vim if necessary.
    - Argorak 12y ago
      I'd sign that. I never use emacs, because I never trained it, but I sometimes use it at a friends machine. It's nothing I find bad or not understandable. All errors stem directly from my lack of skill. (and the different key layout of most of my colleagues)
  - viksit 12y ago
    Hehe because I don't subscribe to monotheism? ;) I prefer vim's modal editing mode and have been using it as my primary for as long as I can remember. For clojure/lisp, I found that the vim tooling was just not as elegant/efficient as emacs (fireside et al arent as nice as cider/swank), and decided to learn how to use it. It's not that much of an "antipattern" because the keymaps are very different. I don't like using vim mode within emacs either - for some reason I find myself thinking in emacs mode when editing lisps. I do think that I could be more productive in emacs if I invested more time in the tutorials, but so far it hasn't been an issue. To me, it's more like needing to know how to use Eclipse or IntelliJ to program in Java since their tooling is so great.
- cies 12y ago
  Have you tried Helm in Emacs? For me it binds to M-x, and I can find a "lost" command by typing just bits. For example "M-x tree undo" show me "undo-tree-visualize (C-x u)". Now I use Helm all over the place: (recent) file opening (within the current project), buffer switching, grepping, etc. It really changed how I interface Emacs.
  - csdrane 12y ago
    What's the advantage of Helm to Ido?
    - rando289 12y ago
      I prefer smex for M-x command matching (which is self described as Ido-style).
    - ludwigvan 12y ago
      Helm by default ands the query terms. Notice how he typed the second word first. Ido searches linearly. Helm is also much more ambitious in general
    - tuhdo 12y ago
      I wrote it in my guide: http://tuhdo.github.io/helm-intro.html#sec-2 http://tuhdo.github.io/helm-intro.html#sec-2
- ams6110 12y ago
  M-x apropos is usually good.
- knome 12y ago
  I hope this terminal mouse business is easy to disable. If I wanted mouse clicks to be registered by emacs, I wouldn't insist on installing emacs-nox versions in the first place.
inzax 12y ago
As shown on https://www.facebook.com/pages/Hacker-News/1558365107716690 https://www.facebook.com/pages/Hacker-News/1558365107716690
Crito 12y ago
> "As always, if you encounter problems building or using Emacs, please send a report to address@hidden with full details" What's up with "address@hidden"?
- tjr 12y ago
  This is the web representation of a mailing list email, and the software that prepares the message for viewing on the web conceals email addresses like that, to help mitigate people receiving unwanted mail (e.g., and probably especially, spam). Had you been on the mailing list and received this content via mail, the address would have ostensibly not been concealed.
- unsignedint 12y ago
  There's also M-x report-emacs-bug (also accessible from the menu Help -> Send Bug Report... which (somewhat) automates bug reporting. It also populates all the information useful for devs. The reporting address seems to be bug-gnu-emacs at gnu.org
timjstewart 12y ago
I'm hoping that the Mac OS X build (http://emacsformacosx.com http://emacsformacosx.com) will soon link with libxml2 so I can use the eww browser. :)
- clamberson 12y ago
  Is there a reason you don't use the Homebrew version of Cocoa Emacs?
  - timjstewart 12y ago
    I did not know about Homebrew's Cocoa Emacs. Thanks for the tip. I'm installing it now and will see if I get 24.4 with eww or some previous version (minus the eww). Thanks again!
    - ndrake 12y ago
      If you ran the install with --devel you should get 24.4-rc1
      - timjstewart 12y ago
        Thanks for the advice!
- Stubb 12y ago
  How's this compare with Aquamacs (http://aquamacs.org http://aquamacs.org)?
  - peatmoss 12y ago
    My feeling is that it's much better than aquamacs. Aquamacs does some things enough differently to regular emacs that I just fine working with homebrew emacs (or emacsforosx) less effort when installing new packages.
- timjstewart 12y ago
iamthebest 12y ago
Very nice! I notice that some bugs have been fixed since I last tried the latest development version(~4 months ago). I really like the enhancement to C-x TAB to use the arrow keys to adjust the indentation on the selected region.
truncate 12y ago
I recently discovered that elisp is dynamically scoped as opposed to lexically scoped. Out of curiosity (as I've never programmed in a dynamically scoped language) hows the experience of working in such language?
- hollerith 12y ago
  Having spent a lot of time with Haskell and Scheme, what irks me the most about working in Emacs Lisp is the fact that it usually involves too much rigamarole or just fails to work for me to use a function that takes a function as an argument or returns a function as a result. E.g., in Haskell, I am fond of using `flip` to reverse two actual arguments just because it makes a line or 3 of code look nicer, and I cannot do that in Emacs Lisp -- or I can, but it involves adding additional lambda forms or calls to funcall or symbol-function (i.e., it involves too much rigamorole). Since I cannot say exactly how far lexical scoping would go in making Emacs Lisp more like Haskell in this regard, this is only a partial answer to your question, but certainly, the lack of lexical scope has something to do with it. Aside from the deficiencies I just mentioned around higher-order functions, I was surprised by how little the lack of lexical scope got in my way. (My reading of the computer-science literature had given me the impression it would cause more trouble than it actually does.)
  - klibertp 12y ago
    Elisp is not Scheme and certainly is not Haskell. You shouldn't - and I'd say it a good general rule - judge Elisp based on what it's not instead of what it is. Getting back to actual question: Elisp supports "real" lexical scoping since previous major Emacs version, and it has had "lexical-let" and other such forms since forever, but most of the code is still dynamically scoped. In practical terms it's similar to having every variable declared as global - it allows for "out of band" communication (outside of arguments passed/value returned) between routines. This is sometimes handy if you want to change some function behaviour in a way that it didn't think of (ie. it has no argument dedicated for this). As a very contrived example, if you have a routine which beeps furiously every time you invoke it and you find it unbearable (I did) you can instead call it like this: (letf (((symbol-function 'beep) (lambda ()))) (beeping-function)) And it won't beep any more. A real life saver sometimes ;) On the other hand, every out-of-band communication has a set of problems to it: you can forget to check it, or you can accidentally pass something to a called function you didn't want to. In practice this is worked around with using longer, prefixed identifiers and the semantics of `let`. As long as every variable your function uses is let-bound inside it it is essentially safe to call with any kind of environment, as it won't ever look at it. Most functions are like that. In short, dynamic scoping has it's advantages and drawbacks, and it feels quite well suited to an extension/scripting language of an app. It makes certain patterns easy enough that they don't even need a name ("monkey patching"), and it makes others much harder (like the linked dash-functional library, which would be very hard to write without lexical-scoping: t).
Yadi 12y ago
Cool updates! is it bad that I still try my best to avoid emacs ? One of my professors loved it, and it just ruined my ideal text editing environment.

Emacs 24.4 RC 1

153 points by Xyzodiac 12y ago

benaiah 12y ago

The current plan is to release on Monday.

webkike 12y ago

This release has so many incredible new features. Great job Emacs team!

viksit 12y ago

As someone who uses emacs purely for clojure/lisp and vim for everything else, the biggest feature for me is the fact that this will be the first version of emacs to support menus in terminal mode. So for all the commands you don't remember, a menu is now a click or F10 away. To quote, "Emacs now supports menus on text-mode terminals. If the terminal supports a mouse, clicking on the menu bar, or on sensitive portions of the mode line or header line, will drop down the menu defined at that position." More at: http://www.masteringemacs.org/article/whats-new-in-emacs-24-4 http://www.masteringemacs.org/article/whats-new-in-emacs-24-...

rezistik 12y ago
As a dev who's always used Sublime/Atom and sometimes Vim, what's the benefit of Emacs for Lisp?
- wglb 12y ago
  Slime
- viksit 12y ago
  There's quite a lot of technology that allows you to write lisp/clojure very well in emacs. Some that come to mind, - Swank/Slime (Lisp inferior modes) that allow you to write lisp, evaluate within the editor, see your results in a buffer. Offer auto complete, refactoring, debugging et al. The more recent nrepl and cider modes for Clojure build on top of slime/swank and offer extremely great tools to write code as well. If you ever wanted to have the REPL running on the side and have great interop between code in a file and the REPL - these modes are great. Imagine their power when you can connect into a running webserver and debug on the fly from within your editor. - A lot of original emacs plugins like paredit have now been ported to other platforms like Sublime. Also, emacs itself is written in lisp, which makes it a first class language it supports at its very core.
  - Havvy 12y ago
    Each lisp varies dramatically in its semantics. Just because emacs is written in e-lisp does not mean it has first class language support for every other lisp. Would you say that vim has first class support for every language with block & statement based languages?
    - viksit 12y ago
      Agree with your high level point. Mine isn't that because it's written in e-lisp, emacs supports every other lisp. The fact that it's written in e-lisp makes it very extensible, and some standard things like C-x C-e to evaluate forms et al, which were originally developed for and are the standard for e-lisp, have been adopted for all other lisp modes as well. The very fact that the editor is written in a lisp makes it expose useful functionality this is useful in other lisp contexts.
- craigching 12y ago
  I can speak about Clojure support for Emacs a bit, but I don't know how much of this Sublime or Atom can do. I like the cider+nrepl workflow myself. You can edit your code, reevaluate it, and test it without having to restart your JVM. As you can imagine, this really speeds up development. Also, though I haven't quite grokked all the barfing and slurping yet, paredit has really become a huge part of my code writing and editing in Emacs for Clojure code. I am on the cusp of getting barfing and slurping working for me now ;)
- BostonEnginerd 12y ago
  Emacs is pretty much a built in REPL primarily written in Lisp.
- malisper 12y ago
  Slime is really amazing. It provides tons of features of which here are a few (these work with Common Lisp, I have no clue if they work with Clojure). Inspector[0]: You can click on objects to "inspect" their values. This includes hash-tables, arrays, and closures. In addition you can execute arbitrary code on these objects at any time, even while a program is running. Trace Dialog[1]: Most Lisp implementations already provide a way to trace procedures. Tracing normally consists of printing the input and the output as each traced procedure is called. Slime provides something much more powerful. Slime's Trace Dialog is similar to trace in that it creates a buffer of the input and output, but instead it is provided in a tree menu format. In addition it is possible to inspect all of the values in the Trace Dialog with the inspector. Debugger[2]: When an error is thrown in a program, a window pops up which provides several things. You can click on a stack frame to see all of the variables in that frame and then inspect those variables with the inspector. You are also provided with a list of restarts[3]. In addition, you can return a value from a given stack frame, or retry a procedure call on the stack frame (you may have modified the definitions of some procedures before you did this), and have the program continue as if nothing had ever happened. There are also many other features, such as the ability to macroexpand code by clicking on it, to look up every procedure which calls a given procedure, to look up every place in which a given variable is set, and many other awesome features. [0] http://common-lisp.net/project/slime/doc/html/Inspector.html http://common-lisp.net/project/slime/doc/html/Inspector.html [1] http://common-lisp.net/project/slime/doc/html/SLIME-Trace-Dialog.html http://common-lisp.net/project/slime/doc/html/SLIME-Trace-Di... [2] http://common-lisp.net/project/slime/doc/html/Debugger.html#Debugger http://common-lisp.net/project/slime/doc/html/Debugger.html#... [3] http://en.wikibooks.org/wiki/Common_Lisp/Advanced_topics/Condition_System#Restarts http://en.wikibooks.org/wiki/Common_Lisp/Advanced_topics/Con...
  - logicchains 12y ago
    That actually sounds a lot like Smalltalk.
    - malkia 12y ago
      Also the editor does not crash if the (lisp) environment becomes unstable (hangs, crashes, etc.) - Such things rarely happen, but they might - for example in Lispworks (which has emacs-like IDE (very nice) but runs the lisp threads in the same process as the editor).
- TeMPOraL 12y ago
  Aside from all the other reasons other people already listed, there is a one fundamental benefit. Emacs is not just an editor, it's a Lisp runtime with text-editing functionality bolted on top. Lisp is natural for Emacs at all levels of complexity - from the fact that it's easy to work with Lisp code using Lisp to the Emacs community, composed in a big part of Lispers. Lisp just fits Emacs.
kstrauser 12y ago
Emacs has had console menus for years. The difference is that they're now clickable, not keyboard-only.
- viksit 12y ago
  Right - but the fact that they behave more like a window manager menu than ever before - as in, they drop down et al.
linuxfan 12y ago
Just curious. How did you manage to use both emacs and vim? I've seen that people accustomed to one editor are usually averse to using the other.
- inclemnet 12y ago
  > I've seen that people accustomed to one editor are usually averse to using the other. I think this is more a meme than necessarily a reality - you'll tend to see a lot more comments online from people who think the old joke is funny or who want to validate their own choice than from people who don't care or have tried both without such strong feelings. In reality, there's really no barrier to 'manage' to use both emacs and vim. If anything, since they're both powerful and configurable programs whose best configuration is personal and some way from the default, it probably is harder to construct your own perfect config in both than for simpler alternatives like web browsers - I guess this may lead to a practical aversion. Personally, I think vim's modal editing is superb but generally prefer the behaviour of emacs' modes and client model, so I use emacs with evil-mode but have no problem using vim if necessary.
  - Argorak 12y ago
    I'd sign that. I never use emacs, because I never trained it, but I sometimes use it at a friends machine. It's nothing I find bad or not understandable. All errors stem directly from my lack of skill. (and the different key layout of most of my colleagues)
- viksit 12y ago
  Hehe because I don't subscribe to monotheism? ;) I prefer vim's modal editing mode and have been using it as my primary for as long as I can remember. For clojure/lisp, I found that the vim tooling was just not as elegant/efficient as emacs (fireside et al arent as nice as cider/swank), and decided to learn how to use it. It's not that much of an "antipattern" because the keymaps are very different. I don't like using vim mode within emacs either - for some reason I find myself thinking in emacs mode when editing lisps. I do think that I could be more productive in emacs if I invested more time in the tutorials, but so far it hasn't been an issue. To me, it's more like needing to know how to use Eclipse or IntelliJ to program in Java since their tooling is so great.
cies 12y ago
Have you tried Helm in Emacs? For me it binds to M-x, and I can find a "lost" command by typing just bits. For example "M-x tree undo" show me "undo-tree-visualize (C-x u)". Now I use Helm all over the place: (recent) file opening (within the current project), buffer switching, grepping, etc. It really changed how I interface Emacs.
- csdrane 12y ago
  What's the advantage of Helm to Ido?
  - rando289 12y ago
    I prefer smex for M-x command matching (which is self described as Ido-style).
  - ludwigvan 12y ago
    Helm by default ands the query terms. Notice how he typed the second word first. Ido searches linearly. Helm is also much more ambitious in general
  - tuhdo 12y ago
    I wrote it in my guide: http://tuhdo.github.io/helm-intro.html#sec-2 http://tuhdo.github.io/helm-intro.html#sec-2
ams6110 12y ago
M-x apropos is usually good.
knome 12y ago
I hope this terminal mouse business is easy to disable. If I wanted mouse clicks to be registered by emacs, I wouldn't insist on installing emacs-nox versions in the first place.

inzax 12y ago

As shown on https://www.facebook.com/pages/Hacker-News/1558365107716690 https://www.facebook.com/pages/Hacker-News/1558365107716690

Crito 12y ago

> "As always, if you encounter problems building or using Emacs, please send a report to address@hidden with full details" What's up with "address@hidden"?

tjr 12y ago
This is the web representation of a mailing list email, and the software that prepares the message for viewing on the web conceals email addresses like that, to help mitigate people receiving unwanted mail (e.g., and probably especially, spam). Had you been on the mailing list and received this content via mail, the address would have ostensibly not been concealed.
unsignedint 12y ago
There's also M-x report-emacs-bug (also accessible from the menu Help -> Send Bug Report... which (somewhat) automates bug reporting. It also populates all the information useful for devs. The reporting address seems to be bug-gnu-emacs at gnu.org

timjstewart 12y ago

I'm hoping that the Mac OS X build (http://emacsformacosx.com http://emacsformacosx.com) will soon link with libxml2 so I can use the eww browser. :)

clamberson 12y ago
Is there a reason you don't use the Homebrew version of Cocoa Emacs?
- timjstewart 12y ago
  I did not know about Homebrew's Cocoa Emacs. Thanks for the tip. I'm installing it now and will see if I get 24.4 with eww or some previous version (minus the eww). Thanks again!
  - ndrake 12y ago
    If you ran the install with --devel you should get 24.4-rc1
    - timjstewart 12y ago
      Thanks for the advice!
Stubb 12y ago
How's this compare with Aquamacs (http://aquamacs.org http://aquamacs.org)?
- peatmoss 12y ago
  My feeling is that it's much better than aquamacs. Aquamacs does some things enough differently to regular emacs that I just fine working with homebrew emacs (or emacsforosx) less effort when installing new packages.
timjstewart 12y ago

iamthebest 12y ago

Very nice! I notice that some bugs have been fixed since I last tried the latest development version(~4 months ago). I really like the enhancement to C-x TAB to use the arrow keys to adjust the indentation on the selected region.

truncate 12y ago

I recently discovered that elisp is dynamically scoped as opposed to lexically scoped. Out of curiosity (as I've never programmed in a dynamically scoped language) hows the experience of working in such language?

hollerith 12y ago
Having spent a lot of time with Haskell and Scheme, what irks me the most about working in Emacs Lisp is the fact that it usually involves too much rigamarole or just fails to work for me to use a function that takes a function as an argument or returns a function as a result. E.g., in Haskell, I am fond of using `flip` to reverse two actual arguments just because it makes a line or 3 of code look nicer, and I cannot do that in Emacs Lisp -- or I can, but it involves adding additional lambda forms or calls to funcall or symbol-function (i.e., it involves too much rigamorole). Since I cannot say exactly how far lexical scoping would go in making Emacs Lisp more like Haskell in this regard, this is only a partial answer to your question, but certainly, the lack of lexical scope has something to do with it. Aside from the deficiencies I just mentioned around higher-order functions, I was surprised by how little the lack of lexical scope got in my way. (My reading of the computer-science literature had given me the impression it would cause more trouble than it actually does.)
- klibertp 12y ago
  Elisp is not Scheme and certainly is not Haskell. You shouldn't - and I'd say it a good general rule - judge Elisp based on what it's not instead of what it is. Getting back to actual question: Elisp supports "real" lexical scoping since previous major Emacs version, and it has had "lexical-let" and other such forms since forever, but most of the code is still dynamically scoped. In practical terms it's similar to having every variable declared as global - it allows for "out of band" communication (outside of arguments passed/value returned) between routines. This is sometimes handy if you want to change some function behaviour in a way that it didn't think of (ie. it has no argument dedicated for this). As a very contrived example, if you have a routine which beeps furiously every time you invoke it and you find it unbearable (I did) you can instead call it like this: (letf (((symbol-function 'beep) (lambda ()))) (beeping-function)) And it won't beep any more. A real life saver sometimes ;) On the other hand, every out-of-band communication has a set of problems to it: you can forget to check it, or you can accidentally pass something to a called function you didn't want to. In practice this is worked around with using longer, prefixed identifiers and the semantics of `let`. As long as every variable your function uses is let-bound inside it it is essentially safe to call with any kind of environment, as it won't ever look at it. Most functions are like that. In short, dynamic scoping has it's advantages and drawbacks, and it feels quite well suited to an extension/scripting language of an app. It makes certain patterns easy enough that they don't even need a name ("monkey patching"), and it makes others much harder (like the linked dash-functional library, which would be very hard to write without lexical-scoping: t).

Yadi 12y ago

Cool updates! is it bad that I still try my best to avoid emacs ? One of my professors loved it, and it just ruined my ideal text editing environment.