5 ms·

Language design: Turtles all the way down, please

21 points by cstejerean 19y ago

dfranke 19y ago
Of course, there would also be things like this: 2 = 3 Which would now pass blithely though the parser only to raise a NoMethodError at run time because numbers do not implement an update method (At least, not in Ruby. Legend has it that this was legal in early versions of FORTRAN. I recall a friend telling me a long time ago that REXX allowed this, but he no longer remembers and I can't verify.
- kajecounterhack 19y ago
  See, thats why big brother is right! 2+2 = 5!
  - michaelneale 19y ago
    <sound of the crack of an assault rifle from behind is heard>
- derefr 19y ago
  When I read the "lvalues and references" part, I thought about functional programming and equivalence. That is, an interpreter where you can state: f(g(h(x))) = n and any time the first was mentioned, it would be substituted with the second, and vice versa, whichever allows the evaluator to simplify to a greater extent. Then, thinking further, are there any programming languages that rely on the sorts of math where f(f^-1(x)) is simplified to x without being evaluated?
  - jey 19y ago
    "Then, thinking further, are there any programming languages that rely on the sorts of math where f(f^-1(x)) is simplified to x without being evaluated?" Mathematica?
- Elepsis 19y ago
  Miserably enough I had to use REXX occasionally in my previous job. I no longer have it to verify, but I wouldn't be terribly surprised if something akin to that were indeed allowed.
davidw 19y ago
I've always taken "turtles all the way down" to mean the fixation that Lisp/Forth/Scheme/Smalltalk/etc... people get about implementing everything in their language of choice, all the way down to the OS and even silicon if they can. This is almost always an enormous waste of time (unless the goal is only to have fun and learn) and of no import to your 'average user'. The scripting language guys came along and got popular because they concentrated on what their languages were good at, and happily interacted with C (and now Java). Also: > I think it's a good thing when languages are highly consistent, in the vein of Scheme, Smalltalk, and Forth Yes and no. It's very elegant, but in the end, I'm not convinced that that's what (most) people really want. Elegant is often a thing to be admired from afar, rather than something you use every day. I'm also in agreement with Larry Wall that sometimes these languages get too hung up on their Elegant Paradigm and forget to be practical.
- shiro 19y ago
  As a programmer who've used Lisp and Scheme for commercial projects, I object to that, although I admit there's a tendency in the circles of these languages that pursue ideals obsessibly. However, "turtles all the way down" has also very practical implications. I have been saved more than once because Lisp/Scheme have the way to tweak very low-level stuff within it so that I can tune the whole program to meet the performance requirements without changing the large structure of the program. And don't take the Scheme guy's discussion about Elegance by their word---we know that tools of day-to-day jobs has to have a kind of dirtiness (I don't despise that; in fact, I rather like to play with lower bits, UI, or legacy workflow,...). We only believe that keeping an eye on the ideal will serve as a long-term guide.
  - davidw 19y ago
    I don't mean that everyone is that obsessed; suffice it to say that enough people have the mentality that they want their entire environment to be in Lisp/Scheme/Smalltalk (the last of which is pretty much that way by design) to have created a culture that is, on average, more concerned with that kind of thing than the scripting languages were - they were too busy getting things done, piggybacking on Unix, C, and Windows to some degree. Note that the Java people have also gone in big for 'turtles all the way down', but that's easier with millions of Sun dollars at your back. My point wasn't that Scheme/Lisp/etc... are impractical languages, or unusable for real work, but more along the lines of "ok, these are great languages, languages that have changed the way everyone thought - so why aren't they more popular? What went wrong?" One very specific example - I recall fooling around with Scheme a while ago, and the implementation I was using didn't even have a string-split (string -> list). Easy to implement? Sure, but also evidence that it wasn't being used for the sort of practical things I wanted to do with it.
gruseom 19y ago
I'm interested in these ideas too. But when there's a clear, obvious antecedent to the discussion it seems to me that it should be cited. http://www.google.com/search?hl=en&rlz=1B3GGGL_enCA237CA238&q=turtles+avi+bryant&btnG=Search http://www.google.com/search?hl=en&rlz=1B3GGGL_enCA237CA...
- raganwald 19y ago
  Ok, here it is: http://en.wikipedia.org/wiki/Turtles_all_the_way_down http://en.wikipedia.org/wiki/Turtles_all_the_way_down
  - gruseom 19y ago
    With all due respect, that's misleading. I'm talking about the application of the turtles meme to a very specific software idea, the one which Alan Kay called recursive design and that you happen to be writing about. As far as I am aware, this particular use of the turtles metaphor was introduced by Avi Bryant in a 2005 post and popularized by him in various interviews since. Surely credit should be given where it is due, especially when an idea has a well-defined origin. It's like writing a whole post about Blub without mentioning "Beating the Averages". (While it is true that the wikipedia page contains a reference to Bryant at the bottom, it's a very obscure reference, and this could hardly be a more specific idea. It's very possible that Avi got it from someone else in the Smalltalk world, but if anyone knows of an earlier published reference I'd be curious to see it.)
    - raganwald 19y ago
      If I am responding directly to someone, I will link to them. If I think there's value to be added for the reader, I will also link to an essay like that. Other than that, I do _not_ insert links and footnotes and citations into every blog post. The footnotes would outnumber the paragraphs if not the sentences. Should I link to Alan Kay every time I discuss objects? How is that different? Or for that matter, if someone discusses the signal-to-noise ratio in programming language idioms, must they mention a post I wrote that was popular at the time? And FYI, I have written about Blub and linked to Paul's essay as well as written about Blub without linking to Paul's essay. You are right, the two things are exactly the same and I have treated them the same way. I choose to link or cite when I think it improves the reader's experience. In this case, I didn't think so, and after re-reading AVi's post, I still don't think a link belongs in my post. You could force it in, perhaps by adding a post script "If you find this interesting, you may also like..." or by adding a parenthetical remark "(TAWDry languages have other benefits, like...)." But you know, that isn't what you are arguing. You do not appear to be arguing that a citation would improve the user experience of the post. Or at least, that's not how it reads. Your comment reads like I have written a scholarly paper and violated the rules of citation. Is that really what you are saying here? There is a saying that I will attribute to Jerry Kaplan (since I read it in the forward to his book "Startup"): "Your ideas will go further if you don't insist on going along with them." Avi hasn't emailed to insist that he go along with that metaphor. Which is probably part of why it is spreading.

21 points by cstejerean 19y ago

Of course, there would also be things like this: 2 = 3 Which would now pass blithely though the parser only to raise a NoMethodError at run time because numbers do not implement an update method (At least, not in Ruby. Legend has it that this was legal in early versions of FORTRAN. I recall a friend telling me a long time ago that REXX allowed this, but he no longer remembers and I can't verify.

kajecounterhack 19y ago
See, thats why big brother is right! 2+2 = 5!
- michaelneale 19y ago
  <sound of the crack of an assault rifle from behind is heard>
derefr 19y ago
When I read the "lvalues and references" part, I thought about functional programming and equivalence. That is, an interpreter where you can state: f(g(h(x))) = n and any time the first was mentioned, it would be substituted with the second, and vice versa, whichever allows the evaluator to simplify to a greater extent. Then, thinking further, are there any programming languages that rely on the sorts of math where f(f^-1(x)) is simplified to x without being evaluated?
- jey 19y ago
  "Then, thinking further, are there any programming languages that rely on the sorts of math where f(f^-1(x)) is simplified to x without being evaluated?" Mathematica?
Elepsis 19y ago
Miserably enough I had to use REXX occasionally in my previous job. I no longer have it to verify, but I wouldn't be terribly surprised if something akin to that were indeed allowed.

davidw 19y ago

I've always taken "turtles all the way down" to mean the fixation that Lisp/Forth/Scheme/Smalltalk/etc... people get about implementing everything in their language of choice, all the way down to the OS and even silicon if they can. This is almost always an enormous waste of time (unless the goal is only to have fun and learn) and of no import to your 'average user'. The scripting language guys came along and got popular because they concentrated on what their languages were good at, and happily interacted with C (and now Java). Also: > I think it's a good thing when languages are highly consistent, in the vein of Scheme, Smalltalk, and Forth Yes and no. It's very elegant, but in the end, I'm not convinced that that's what (most) people really want. Elegant is often a thing to be admired from afar, rather than something you use every day. I'm also in agreement with Larry Wall that sometimes these languages get too hung up on their Elegant Paradigm and forget to be practical.

shiro 19y ago
As a programmer who've used Lisp and Scheme for commercial projects, I object to that, although I admit there's a tendency in the circles of these languages that pursue ideals obsessibly. However, "turtles all the way down" has also very practical implications. I have been saved more than once because Lisp/Scheme have the way to tweak very low-level stuff within it so that I can tune the whole program to meet the performance requirements without changing the large structure of the program. And don't take the Scheme guy's discussion about Elegance by their word---we know that tools of day-to-day jobs has to have a kind of dirtiness (I don't despise that; in fact, I rather like to play with lower bits, UI, or legacy workflow,...). We only believe that keeping an eye on the ideal will serve as a long-term guide.
- davidw 19y ago
  I don't mean that everyone is that obsessed; suffice it to say that enough people have the mentality that they want their entire environment to be in Lisp/Scheme/Smalltalk (the last of which is pretty much that way by design) to have created a culture that is, on average, more concerned with that kind of thing than the scripting languages were - they were too busy getting things done, piggybacking on Unix, C, and Windows to some degree. Note that the Java people have also gone in big for 'turtles all the way down', but that's easier with millions of Sun dollars at your back. My point wasn't that Scheme/Lisp/etc... are impractical languages, or unusable for real work, but more along the lines of "ok, these are great languages, languages that have changed the way everyone thought - so why aren't they more popular? What went wrong?" One very specific example - I recall fooling around with Scheme a while ago, and the implementation I was using didn't even have a string-split (string -> list). Easy to implement? Sure, but also evidence that it wasn't being used for the sort of practical things I wanted to do with it.

gruseom 19y ago

I'm interested in these ideas too. But when there's a clear, obvious antecedent to the discussion it seems to me that it should be cited. http://www.google.com/search?hl=en&rlz=1B3GGGL_enCA237CA238&q=turtles+avi+bryant&btnG=Search http://www.google.com/search?hl=en&rlz=1B3GGGL_enCA237CA...

raganwald 19y ago
Ok, here it is: http://en.wikipedia.org/wiki/Turtles_all_the_way_down http://en.wikipedia.org/wiki/Turtles_all_the_way_down
- gruseom 19y ago
  With all due respect, that's misleading. I'm talking about the application of the turtles meme to a very specific software idea, the one which Alan Kay called recursive design and that you happen to be writing about. As far as I am aware, this particular use of the turtles metaphor was introduced by Avi Bryant in a 2005 post and popularized by him in various interviews since. Surely credit should be given where it is due, especially when an idea has a well-defined origin. It's like writing a whole post about Blub without mentioning "Beating the Averages". (While it is true that the wikipedia page contains a reference to Bryant at the bottom, it's a very obscure reference, and this could hardly be a more specific idea. It's very possible that Avi got it from someone else in the Smalltalk world, but if anyone knows of an earlier published reference I'd be curious to see it.)
  - raganwald 19y ago
    If I am responding directly to someone, I will link to them. If I think there's value to be added for the reader, I will also link to an essay like that. Other than that, I do _not_ insert links and footnotes and citations into every blog post. The footnotes would outnumber the paragraphs if not the sentences. Should I link to Alan Kay every time I discuss objects? How is that different? Or for that matter, if someone discusses the signal-to-noise ratio in programming language idioms, must they mention a post I wrote that was popular at the time? And FYI, I have written about Blub and linked to Paul's essay as well as written about Blub without linking to Paul's essay. You are right, the two things are exactly the same and I have treated them the same way. I choose to link or cite when I think it improves the reader's experience. In this case, I didn't think so, and after re-reading AVi's post, I still don't think a link belongs in my post. You could force it in, perhaps by adding a post script "If you find this interesting, you may also like..." or by adding a parenthetical remark "(TAWDry languages have other benefits, like...)." But you know, that isn't what you are arguing. You do not appear to be arguing that a citation would improve the user experience of the post. Or at least, that's not how it reads. Your comment reads like I have written a scholarly paper and violated the rules of citation. Is that really what you are saying here? There is a saying that I will attribute to Jerry Kaplan (since I read it in the forward to his book "Startup"): "Your ideas will go further if you don't insist on going along with them." Avi hasn't emailed to insist that he go along with that metaphor. Which is probably part of why it is spreading.