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> That language is an instrument of human reason, and not merely a medium for the expression of thought, is a truth generally admitted. And Sapir-Whorf rears i

> That language is an instrument of human reason, and not merely a medium for the expression of thought, is a truth generally admitted. And Sapir-Whorf rears its ugly head again.

btilly 17y ago
But it actually has some truth in programming. There is little possibility of thinking with programming techniques that require closures until you are thinking in a programming language that has closures. Learning the language does not cause the thoughts, but you cannot think through the thoughts effectively until you've developed a language that can express them. Of course once you have learned to think those thoughts then you can figure out how to do those things in languages that don't have closures. This raises, obviously, the question of how the idea of closures was ever first established. And the answer to that is kind of interesting. The history as I understand it is that they were invented by accident as a side effect of other decisions in ALGOL and Pascal. But weren't extensively used there. Then Sussman noticed that they worked extremely well when combined with the idea of functions as data that was already popular in Lisp, and co-wrote Scheme, the first Lisp with closures. The adoption of closures in other variants of Lisp was usually quick (eLisp stands out as a glaring exception). From there they got carried to other languages. The adoption of closures in scripting languages, particularly JavaScript, brought them to a much wider audience, and now they are becoming pretty mainstream. So nobody really thought up the first programming techniques involving closures from scratch. Instead those techniques were invented in a bad form using other forms of scope, then closures were noticed as a solution for the shortcomings of those scoping problems and things cascaded from there.
- RyanMcGreal 17y ago
  > But it actually has some truth in programming. I've learned a few programming languages over the years and I generally accept the Blub Paradox (right now I'm contemplating the prospect that Python is Blub), but I still think this line of reasoning gets it backwards - particularly given that programming languages are invented. Of course serendipity comes into play, but to suggest that it might have been impossible to imagine effective closures until a programming language accidentally supported them (poorly) just seems absurd.
  - btilly 17y ago
    I will never forget the brain lock I encountered the first time I had to deal with a relatively small program that made extensive use of closures. In hindsight the program was well-designed and clearly written. Yet I simply could not understand it for over at least half an hour. And even once I did figure it out, it took days before I could truly digest what made that design work. A couple of years later on the Perl 5 core mailing list I responded to a claim that a good Perl programmer could support any well-written Perl program with a key line from that program. From the volume of the squawks I got, a collection of good Perl programmers generally were not prepared to understand that code, despite years of experience in a language that fully supported closures. I will not claim that it is impossible to imagine effective closures. I know there are people who are far more intelligent than me, who think very differently than I do. If history played out again a few times, perhaps it would play out differently. But I say without false modesty that I'm a significantly above average programmer, and I am convinced that I personally could not have come up with effective closures on my own. And I've known quite a few good programmers who I am sure could not have done it. And I've never personally known anyone who has left me convinced that they could have done it. And finally the history of how closures were invented does not support the idea that someone imagined what could be done with them and then invented them for that reason.
    - RyanMcGreal 17y ago
      > the history of how closures were invented does not support the idea that someone imagined what could be done with them and then invented them for that reason. Most really interesting and disruptive inventions are at least partially accidental. Ideas rarely spring fully formed; instead they appear through cross-fertilization, recombination and serendipity. Once the idea is there, we invent whatever models and languages are necessary to describe and implement it. That process can be comprehensive and all-at-once but more often is iterative and progressive. Even radical innovations that seem to spring fully formed did so after long gestation outside public view.
    - eru 17y ago
      Thanks. An interesting story. About your last paragraph: What's so special about closures? They have been in lambda-calculus for ages. And lambda-calculus just formalizes mathematicial function application and abstraction. (OK, I guess most mathematicians are not aware of lexical scoping. But it springs naturally from alpha equivalence, a notion that every mathematician agrees with intuitively.) Of course coming up with the mathematical ideas and notations in the first place wasn't easy. But closures pre-date computers. The computer scientists `just' had to find ways to implement them effectively.

> That language is an instrument of human reason, and not merely a medium for the expression of thought, is a truth generally admitted. And Sapir-Whorf rears its ugly head again.

btilly 17y ago

But it actually has some truth in programming. There is little possibility of thinking with programming techniques that require closures until you are thinking in a programming language that has closures. Learning the language does not cause the thoughts, but you cannot think through the thoughts effectively until you've developed a language that can express them. Of course once you have learned to think those thoughts then you can figure out how to do those things in languages that don't have closures. This raises, obviously, the question of how the idea of closures was ever first established. And the answer to that is kind of interesting. The history as I understand it is that they were invented by accident as a side effect of other decisions in ALGOL and Pascal. But weren't extensively used there. Then Sussman noticed that they worked extremely well when combined with the idea of functions as data that was already popular in Lisp, and co-wrote Scheme, the first Lisp with closures. The adoption of closures in other variants of Lisp was usually quick (eLisp stands out as a glaring exception). From there they got carried to other languages. The adoption of closures in scripting languages, particularly JavaScript, brought them to a much wider audience, and now they are becoming pretty mainstream. So nobody really thought up the first programming techniques involving closures from scratch. Instead those techniques were invented in a bad form using other forms of scope, then closures were noticed as a solution for the shortcomings of those scoping problems and things cascaded from there.

RyanMcGreal 17y ago
> But it actually has some truth in programming. I've learned a few programming languages over the years and I generally accept the Blub Paradox (right now I'm contemplating the prospect that Python is Blub), but I still think this line of reasoning gets it backwards - particularly given that programming languages are invented. Of course serendipity comes into play, but to suggest that it might have been impossible to imagine effective closures until a programming language accidentally supported them (poorly) just seems absurd.
- btilly 17y ago
  I will never forget the brain lock I encountered the first time I had to deal with a relatively small program that made extensive use of closures. In hindsight the program was well-designed and clearly written. Yet I simply could not understand it for over at least half an hour. And even once I did figure it out, it took days before I could truly digest what made that design work. A couple of years later on the Perl 5 core mailing list I responded to a claim that a good Perl programmer could support any well-written Perl program with a key line from that program. From the volume of the squawks I got, a collection of good Perl programmers generally were not prepared to understand that code, despite years of experience in a language that fully supported closures. I will not claim that it is impossible to imagine effective closures. I know there are people who are far more intelligent than me, who think very differently than I do. If history played out again a few times, perhaps it would play out differently. But I say without false modesty that I'm a significantly above average programmer, and I am convinced that I personally could not have come up with effective closures on my own. And I've known quite a few good programmers who I am sure could not have done it. And I've never personally known anyone who has left me convinced that they could have done it. And finally the history of how closures were invented does not support the idea that someone imagined what could be done with them and then invented them for that reason.
  - RyanMcGreal 17y ago
    > the history of how closures were invented does not support the idea that someone imagined what could be done with them and then invented them for that reason. Most really interesting and disruptive inventions are at least partially accidental. Ideas rarely spring fully formed; instead they appear through cross-fertilization, recombination and serendipity. Once the idea is there, we invent whatever models and languages are necessary to describe and implement it. That process can be comprehensive and all-at-once but more often is iterative and progressive. Even radical innovations that seem to spring fully formed did so after long gestation outside public view.
  - eru 17y ago
    Thanks. An interesting story. About your last paragraph: What's so special about closures? They have been in lambda-calculus for ages. And lambda-calculus just formalizes mathematicial function application and abstraction. (OK, I guess most mathematicians are not aware of lexical scoping. But it springs naturally from alpha equivalence, a notion that every mathematician agrees with intuitively.) Of course coming up with the mathematical ideas and notations in the first place wasn't easy. But closures pre-date computers. The computer scientists `just' had to find ways to implement them effectively.