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CoffeeScript has different semantics from JavaScript, and the obvious expansion of CoffeeScript back into JavaScript is a wrong expansion Nothing in the post s

CoffeeScript has different semantics from JavaScript, and the obvious expansion of CoffeeScript back into JavaScript is a wrong expansion Nothing in the post supports this assertion. You may have your own reasons for feeling this way, but the difference between JavaScript and CoffeeScript with respect to the "var" keyword is neither subtle nor obvious, given that CoffeeScript does not have a var keyword. The only possible source of literal misinterpretation would be to look at a CoffeeScript file and think that every variable that wan't a parameter was a global variable. This is extremely unlikely in practice. I read you as being biased against using it. FIne with me, Chief, go your way in peace. But don't try to twist my example into support for a decision you have already made.

shaunxcode 14y ago
The thing I used to hate about smalltalk was having to define the temporary vars at the top of the method/block. Now it just seems like a great idea which clarifies any sort of ambiguity like this.
ynniv 14y ago
the difference between JavaScript and CoffeeScript with respect to the "var" keyword is neither subtle nor obvious, given that CoffeeScript does not have a var keyword. Great, then every variable in CoffeeScript must be global, because that's the semantics of a non-parameter not be declared a "var" in JavaScript. Except that this is not an accurate translation, as the entire post goes on to explain scoping in CoffeeScript. The only possible source of literal misinterpretation would be to look at a CoffeeScript file and think that every variable that wan't a parameter was a global variable. This is extremely unlikely in practice. Screwing up scoping is an extremely common JavaScript mistake. If you showed me JavaScript-like code and told me there was a bug, the first thing I would point out is that you declared everything globally. Oh, that isn't the case in CoffeeScript? Huh, I guess you're on your own then, because I didn't learn your goofy alternative JavaScript syntax. Maybe you think the junior kid who has a bug in his code is going to properly explain the subtlety of CoffeeScript scoping. FIne with me, Chief, go your way in peace. But don't try to twist my example into support for a decision you have already made. It's offensive of you to dismiss my criticism in this forum. I am not prejudiced against new things, and while CoffeeScript doesn't seem like a worthwhile idea to me, it's community is far more offensive. CoffeeScript's demagoguery of JavaScript might impress some folks, but outside ruby-like syntax, CoffeeScript doesn't solve any fundamental issues. So, "go your way in peace", and leave me to my thoughts, please.
- raganwald 14y ago
  As every debate ought to say, we're each entitled to our own opinions, but not our own facts. My opinion--which I believe I have demonstrated to be a fact--is that it is possible to write sane CoffeeScript that is lexically scoped and not subject to misinterpretation. It is a fact that it is possible to write CoffeeScript code that requires careful examination of the file to understand what it does, code which can also change if you alter something somewhere else in the file. My opinion--which I also believe I have demonstrated to be a fact--is that it is possible to write sane JavaScript that is lexically scoped and not subject to misinterpretation. It is clearly possible to write JavaScript code that requires careful examination of the file to understand what it does, acode which can also change if you alter something somewhere else in the file. I have zero quibble with you or anyone else feeling CoffeeScript doesn't solve a problem for them. I have zero quibble with you or anyone else saying "Notwithstanding the fact that CoffeeScript is a lexically scoped language, my opinion is that I hate it." My only quibble--and it is minor--is that it is not possible to say that CoffeeScript function-local variables don't work like JavaScript function-local variables and that you can confuse the two, since without the var keyword nobody can look at a CoffeeScript file and think they are looking at function-local variables. We both agree on the fact that a file with variables that are not parameters in CoffeeScript has different semantics from a file with variables that are neither parameters nor function-local in JavaScript. If your opinion is that this is a fatal flaw, well, who am I to argue with the fact that this is your opinion? I have a different opinion, and we are both entitled to same provided neither of us claim it to be a fact.
  - ynniv 14y ago
    My assertion is that CoffeeScript is not an alternative syntax for JavaScript because of differences in scoping. My opinion is that this is not a good design choice because it increases the separation from the original language, requiring that someone who already knows JavaScript additionally learn CoffeeScript. You can take the rest of my original comment as a rehashing of my evaluation of CoffeeScript, since I only see it when it appers on Hacker News.
    - 14y ago
lmm 14y ago
>the difference between JavaScript and CoffeeScript with respect to the "var" keyword is neither subtle nor obvious, given that CoffeeScript does not have a var keyword The thing that is subtle and nonobvious as a javascript programmer is the way CoffeeScript variables are scoped. They are not scoped like "var" variables in javascript. They are not scoped like "non-var" variables in javascript either. They have their own kind of scope that is unique to CoffeeScript. Now you can argue that the way javascript scopes variables is wrong, and I'd agree with you. You can argue that the CoffeeScript way is better, and that's fine. But it makes it a different language from JavaScript, and it has all the baggage that goes along with that. You can't just treat CoffeeScript as "javascript with a nicer syntax"; you need to approach it the same way you'd approach learning any new language.

shaunxcode 14y ago

The thing I used to hate about smalltalk was having to define the temporary vars at the top of the method/block. Now it just seems like a great idea which clarifies any sort of ambiguity like this.

ynniv 14y ago

the difference between JavaScript and CoffeeScript with respect to the "var" keyword is neither subtle nor obvious, given that CoffeeScript does not have a var keyword. Great, then every variable in CoffeeScript must be global, because that's the semantics of a non-parameter not be declared a "var" in JavaScript. Except that this is not an accurate translation, as the entire post goes on to explain scoping in CoffeeScript. The only possible source of literal misinterpretation would be to look at a CoffeeScript file and think that every variable that wan't a parameter was a global variable. This is extremely unlikely in practice. Screwing up scoping is an extremely common JavaScript mistake. If you showed me JavaScript-like code and told me there was a bug, the first thing I would point out is that you declared everything globally. Oh, that isn't the case in CoffeeScript? Huh, I guess you're on your own then, because I didn't learn your goofy alternative JavaScript syntax. Maybe you think the junior kid who has a bug in his code is going to properly explain the subtlety of CoffeeScript scoping. FIne with me, Chief, go your way in peace. But don't try to twist my example into support for a decision you have already made. It's offensive of you to dismiss my criticism in this forum. I am not prejudiced against new things, and while CoffeeScript doesn't seem like a worthwhile idea to me, it's community is far more offensive. CoffeeScript's demagoguery of JavaScript might impress some folks, but outside ruby-like syntax, CoffeeScript doesn't solve any fundamental issues. So, "go your way in peace", and leave me to my thoughts, please.

raganwald 14y ago
As every debate ought to say, we're each entitled to our own opinions, but not our own facts. My opinion--which I believe I have demonstrated to be a fact--is that it is possible to write sane CoffeeScript that is lexically scoped and not subject to misinterpretation. It is a fact that it is possible to write CoffeeScript code that requires careful examination of the file to understand what it does, code which can also change if you alter something somewhere else in the file. My opinion--which I also believe I have demonstrated to be a fact--is that it is possible to write sane JavaScript that is lexically scoped and not subject to misinterpretation. It is clearly possible to write JavaScript code that requires careful examination of the file to understand what it does, acode which can also change if you alter something somewhere else in the file. I have zero quibble with you or anyone else feeling CoffeeScript doesn't solve a problem for them. I have zero quibble with you or anyone else saying "Notwithstanding the fact that CoffeeScript is a lexically scoped language, my opinion is that I hate it." My only quibble--and it is minor--is that it is not possible to say that CoffeeScript function-local variables don't work like JavaScript function-local variables and that you can confuse the two, since without the var keyword nobody can look at a CoffeeScript file and think they are looking at function-local variables. We both agree on the fact that a file with variables that are not parameters in CoffeeScript has different semantics from a file with variables that are neither parameters nor function-local in JavaScript. If your opinion is that this is a fatal flaw, well, who am I to argue with the fact that this is your opinion? I have a different opinion, and we are both entitled to same provided neither of us claim it to be a fact.
- ynniv 14y ago
  My assertion is that CoffeeScript is not an alternative syntax for JavaScript because of differences in scoping. My opinion is that this is not a good design choice because it increases the separation from the original language, requiring that someone who already knows JavaScript additionally learn CoffeeScript. You can take the rest of my original comment as a rehashing of my evaluation of CoffeeScript, since I only see it when it appers on Hacker News.
  - 14y ago

lmm 14y ago

>the difference between JavaScript and CoffeeScript with respect to the "var" keyword is neither subtle nor obvious, given that CoffeeScript does not have a var keyword The thing that is subtle and nonobvious as a javascript programmer is the way CoffeeScript variables are scoped. They are not scoped like "var" variables in javascript. They are not scoped like "non-var" variables in javascript either. They have their own kind of scope that is unique to CoffeeScript. Now you can argue that the way javascript scopes variables is wrong, and I'd agree with you. You can argue that the CoffeeScript way is better, and that's fine. But it makes it a different language from JavaScript, and it has all the baggage that goes along with that. You can't just treat CoffeeScript as "javascript with a nicer syntax"; you need to approach it the same way you'd approach learning any new language.