Re: url-retrieve fails on most HTTPS sites

[tomas]

On Tue, Sep 29, 2020 at 11:49:07AM +0200, Emanuel Berg via Users list for the 
GNU Emacs text editor wrote:
> tomas wrote:
> 
> > Things become more interesting if the thing coming
> > after #' is a symbol, like in #'car.
> 
> The use case, at least mine, is to denote functions
> so the byte-compiler can check if they are defined.
> Makes development faster and more pleasant...
> 
> Yeah ... what _is_ the origin/reason of this thing,
> deep down? That symbols are not only a value or
> a function but both, and more?
> 
>   symbol-function
>   symbol-value
>   ...

Exactly.

> > Then we all know we are talking about car's
> > symbol-function. This allows the human code readers
> > and the compiler to be smarter about the code.
> 
> Yeah, however what gain is there to mucking with
> that? That cannot be solved, or solved in a worse
> way, with "dedicated symbols", I guess?

Well, #' is just a shorthand for function, just as ' is a
shorthand for quote.

If you do #'car (or, what's the same (function car)), the
compiler can, for example, warn you early that there's no
function named like this (for the symbol car, your Lisp would
be... in a strange state, but you get the idea :)

Plus lots of other optimizations the compiler can do if it
knows that it's the function value you are talking about.

Plus the clarity of your code for your other readers.

All of that isn't necessary for (lambda (...) ...), since
it's lambda's job to make functions. We know that, the
compiler knows that.

Cheers
 - t

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