I was able to learn C reasonably well as a child precisely because of how straightforward it is. You can reserve a block of memory. You can free it. You can get the address of a value. You can get the value from an address. It works in an extremely straightforward way, unlike most languages. To a child, programming in C feels like the computer is doing exactly what it was told to do and nothing else. It feels like you understand what is going on, even though your understanding is a very simplified model of what is actually going on.
This is an issue with learning a new language when you've already got your mind molded to a different one.
JS programmers have the exact opposite issue when learning C. Why can't we do this? Why must we worry about scopes for the stack? Wtf is the stack? I wonder what happens if I try to use this variabSEGMENTATION FAULT.
These languages generally are dealt with differently in one's mind, and trying to apply the mental model from language 1 to language 2 usually makes it feel harder than it really is.
I really could say the same about "it feels like the computer is doing exactly what you told it to do" about the other languages you listed. A crucial part is that you don't actually need to understand what the computer is doing under the hood to use it, especially in a higher level language. C is more like "you were forced to talk to the computer in its own language", whereas with JS/C#/etc you don't have to know what addresses and memory are. You just tell the computer what tasks you want done, and how to model them, and it does them.
So I'm very skeptical that the other modern languages you listed are harder to understand than C. They're just different.
So unless learning C somehow causes permanent disability I will have to respectfully disagree.
C sort of does cause a disability (not really a disability, this is a useful skill!) in the sense that now you're actually thinking about how a language feature works in the hardware, which is not something you necessarily need to do for higher level languages. The moment you ignore all this it's likely that the language will make sense again. Of course, like I said, this is all subjective. The solution to "I can't use async/await because I don't understand how they work" is basically that you pretend that they're magic, and try to figure out the internals on the side. You need not understand how things work under the hood to use them, though it is an extremely valuable skill to know what C#/JS/etc end up doing at the lower level.
It's a sort of "ignorance is bliss" situation.
It varies from person-to-person though. It's not specific to programming either. When I was a physics student I personally would be easily able to define layers of abstraction in my mind and work within one layer, even if I didn't understand another -- you ignore how the other layer works and assume that it is magic (while simultaneously working to understand the other layer). One of my friends could not do this -- he had to understand rigorously how the theorems worked all the way down. As you can imagine, this required a lot of effort. It meant that he always had a thorough understanding of the topic at hand, but often meant that he spent a lot more time to understand something and had no middle ground to choose.
For me, this has carried over to programming. If I'm dealing with a language like C or C++ I will try to understand how everything works on the metal. When I first learned about C99 VLAs I spent an hour mucking with a debugger and inspecting the stack. When I realized that C++ had function-local initialized statics I spent many hours digging through C++ spec/implementations to understand how it worked (http://manishearth.github.io/blog/2015/06/26/adventures-in-s...). These are things at the same abstraction level as C/++ which I must understand to be able to use them.
But when I'm dealing with languages like JS, I can operate perfectly fine without knowing how they work. Indeed, when I first learned about generators, I was able to use them for quite a while before I learned how they work. I still want to know how things work (and generally dig into it), but it doesn't block me from proceeding if I don't.
This is not how everyone approaches languages. Like I said, it is subjective.
That's only weird to you because C doesn't do it.
For someone starting in one of those languages, it simply makes sense that I can use any variable in scope. (Stack allocation? What is this sorcery you speak of?)
Because stack allocation has nothing to do with C, C is not explicit about doing it (except alloca) just like most other languages, and other languages use it just like C does, including C# with its closures and async/await. It even has stackalloc.
In C, a variable's lifetime is limited to the current function call. The natural implementation of C is to track both function calls and variables on stack structure with statically determined offsets. Thus, C has stack-allocated variables.
Since a Clojure variable's lifetime is not limited to the current function call, C's implementation details aren't relevant. Stack-allocated variables are a bizarre notion.
In reality it comes from trying to apply how that language works in normal cases (in the absence of those features), and the features requiring special compiler magic to work.
Yes if variable lifetime is as you describe in Clojure then that sentence doesn't make sense for Clojure.
As I've already told someone else, it is unlikely that learning C at some point in your life (not as my first language, not as the language I use professionaly, not even in my top 3 most used languages) permanently cripples your ability to understand other languages.
In any non-systems language you don't need to know (and knowing it doesn't help you with anything) this stack sorcery you're talking about.
You can mess with the stack in C, you can also mess with the stack in C#. But you don't have to, and normally you don't. You use it in a completely transparent manner, not caring where the compiler decides to put your data.
When it comes to stack allocation, in C this is the compiler's decision and in JS this is the execution engine's decision.
In JS, that quote makes perfect sense, and the answer is: the engine checks what can be safely put on the stack, and the stuff that is closed over is stored on the heap to avoid losing it when the function returns.
And everything function parameter is passed as value. In many 'advanced' languages, some things are passed by value, other by reference depending on the type, sometimes automatically, sometimes manually, it took me years to figure that out.
Same things for loops.
And I still have nightmares about some languages memory models: what is allocated where? what kind of allocation was performed on the object that this function returned, do I have to free it manually or will it disappear when I leave the scope? which scope? is it on the stack or is it the GC that takes care of it? when does it take care of it? should I call it manually?