The way you know it's magic is it shatters the principle of referential identity, which tells you that a variable is itself. It pretends you can use a simpler mental model but you really cannot and must not.
"React Functional Components" have nothing to do with conventional functional programming. They inherently (intentionally?) violate the spirit of functional programming through hidden global variables, while pretending that it is still functional, when in reality they should be doing the opposite. They should be upfront about the hack that hooks are. They are not functional, they are merely functions. In all other respects they operate as if the function was a method inside a class and that all hook calls are with respect to an invisible "this" keyword that contains the component's context. Since hooks are not named (which would expose their inherently pseudo-OOP nature), they associate their state through a hidden incrementing counter. It's like you're sweeping all the OOP parts under the rug to pretend to be functional so you can be a cool functional hippie too.
The thing is ... you can model effects with the Free monad (or with Haskell's Backpack as was on here just the other day - https://www.hackerneue.com/item?id=45221112), so they are definitely "functional", for most variations on the definition of "functional" that I know.
This happens because GUIs are inherently imperative constructs.
Functional literally means dealing with functions composition.
Free of side effect is not a property of functional programming. Ocaml is functional and has side effects.
Next you're going to complain about the fact that the compiler handles static variables with controlled allocations for you in C.
Like there's no rational basis for your complaints or critique other than grandstanding.
When you do a useValue() it is clear you are grasping at something with a larger lifespan than your function.
Conceptually it is not much different than
int counter() {
static int x = 1;
return x++;
}
Thats what makes it a new language. C is just sugar on top of assembly.
Its so strange that jsx needs a buildstep, but misses ton of obvious ergonomics that one could have added. Why className instead of class? With a buildstep, it would surely be possible to determine if class was a keyword or not based on context
I think that's a bad example. C isn't a sugar for assembly: For example what assembly code does a function prototype desugar into? Sugars have 1:1 mappings with host code
Maybe you're just being rhetorical about the spectrum of macros, sugars, and languages, though.
(In my opinion, a better target for that criticism, in JS land, is the Jest test framework, because of all the reordering magic it does that break fundamental ES semantics)
> Why className instead of class?
This hasn't been a constraint since... I want to say React 18, six or seven years ago? I might be misremembering the history but I think that was only a problem in the Early Days when there was paranoia about whether JSX needed to be conservative with reserved keywords
More like syntax cilantro. Some people love it. Some can't stand it.
It would be best to think of it as syntax sugar for create Element() function calls. You enter JSX with angle tags and insert expressions in braces
> React is full of magic syntax that looks like functions, but e.g. you can't call them inside an if statement, or you have to redundantly declare the 'dependencies' (variables you read) and so on
That's not magic syntax. That's just functions that must be processed in regular order between render ticks.
It's not a difficult exercise to write a "plain JS" function that works that way. If you've worked much with closures you can visualise how that would play out.