As Alexis notes, getting the arrows right in general is tricky. But `block`
is also currently buggy in that it does not expand to `#%expression` when
not in an expression context. (`block` is buggy in at least one other way
as well, but that needs a deeper fix:
https://github.com/racket/racket/
> On Jun 7, 2020, at 17:44, Sorawee Porncharoenwase
> wrote:
>
> Wow, so block is currently buggy?!
>
This issue isn’t with `block`, per se (though `block` could cooperate more
nicely with definition context expansion to avoid this problem). You can
reproduce it without any first-class defin
Thanks for the info, Brian.
I'm getting the impression that Scheme/Racket Web production serving is
sorta in same place it has been for the last couple decades: such that a
really good and prolific developer can make a system work well in
production, iff they can put in a lot of work beyond of
Wow, so block is currently buggy?!
On Sun, Jun 7, 2020 at 3:31 PM Michael Ballantyne <
michael.ballant...@gmail.com> wrote:
> Hah! You're right. The arrow points to the inner definition. But it's even
> worse than that---the value comes from the outer definition! At least for
> `block`, which is
Hah! You're right. The arrow points to the inner definition. But it's even
worse than that---the value comes from the outer definition! At least for
`block`, which is what I'm testing with as I haven't copied down your code.
Try this:
#lang racket
(require racket/block)
(define-syntax-rule (m
Perhaps I missed something, but the error in the first example is because
there’s no expression at the end of let. If I use this code instead, it
seems to work fine, with the arrow of m pointing to the “new” one.
(define-syntax-rule (m) 'old)
(let ()
(list+ (m))
(define-syntax-rule (m) 'new)
Small update on this: I've updated the benchmarks to run multiple Racket
processes with an Nginx load balancer in front. After some tuning[1], here
is what the results look like on my 12 core AMD Ryzen 9 3900 server:
https://www.techempower.com/benchmarks/#section=test&shareid=669bfab7-9242-4c26-
Den søn. 7. jun. 2020 kl. 14.09 skrev Siyuan Chen :
Unfortunately, this code doesn't work, because it lacks two functions,
> `get-current-env` and `extends-env`.
>
These are not available since static lexical scope makes it possible for
the compiler to determine where
a variable is stored at comp
On Sun, Jun 07, 2020 at 08:09:40PM +0800, Siyuan Chen wrote:
...
...
>
> There is an alternative of Lisp macros called FEXPRs, see
> https://en.wikipedia.org/wiki/Macro_(computer_science)#Early_Lisp_macros
>
> > Early Lisp macros
> > Before Lisp had macros, it had so-called FEXPRs, function-like
> I am unable to come up with a program where this difference is
significant though
Here's an example:
(define-syntax-rule (m) 'old)
(let ()
($list
(m))
(define-syntax-rule (m) 'new))
> So I am curious why internal-definition-context-track is needed.
A similar example shows the need
Dear all,
** Note that this question is not for practical programming, but just play
for fun.**
I want to implement Maybe monad in Racket.
The following code works.
```
(struct Just (a)
#:transparent)
(struct Nothing ()
#:transparent)
(define (bigger-than-two n)
(if (> n 2)
(Ju
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