[racket-users] Re: make-readtable with no arguments produces an incompatible readtable?

After some investigation, I’ve decided that this behavior is, indeed a bug, and I’ve opened a relevant bug report here: https://github.com/racket/racket/issues/1118 This brings me to a new and different question: how can I work around this? Even if the bug is fixed, it will only be fixed on

[racket-users] let/define

Hi all, Some of my creative students came up with the following: (let ([y 5]) (begin (display y) (define y 10) y))) which raises a mysterious y: undefined; cannot use before initialization I remember earlier discussion on this list about the fact that `define' was somehow “broken”

[racket-users] Changing reader parameters from within a reader extension

Hi all, I’m continuing to implement R7RS in Racket, and I think I’ve gotten most of the way aside from the various reader differences. The trickiest thing seems to be the #!fold-case and #!no-fold-case directives, which adjust the case-sensitivity of the reader as a side-effect. I’ve

[racket-users] Re: Evolving camouflage with Racket games

> Am I missing something? I'd guess that brightly-coloured objects (in a environment where there is neither "poisonous" nor "pretending I'm poisonous") tend to get noticed and clicked more often ? So after a while bright colors "die out" / tend to not get generated ? -- You received this

Re: [racket-users] let/define

This is because begin can have potentially recursive and mutually recursive definitions in it. This does the same thing: (let ([y 5]) (local [(define x y) ; this y should be bound to (define y 10)] ; <- this y, but it is used too early y)) While this slightly different case

Re: [racket-users] Changing reader parameters from within a reader extension

I see that the documentation for Racket's `read` and `read-syntax` needs to be adjusted to say that the values of various parameters are relevant only when the `read` or `read-syntax` starts. (Trying to make them adapt dynamically in general would be impractical, I think; a custom port's

[racket-users] Feasibility of Racket for scientific and engineering calculations

Hi all, I am exploring whether Racket could be a Lisp replacement for Python in scientific and engineering calculations. I currently use Python extensively in teaching chemical engineering courses (http://kitchingroup.cheme.cmu.edu/pycse/) and in running molecular simulations

Re: [racket-users] let/define

Yeah, perhaps I've drunk too much of the koolaid, but I'm not even seeing an alternative interpretation that makes any sense! Does it help to see the arrows in DrRacket? In particular the upward pointing one that points at the 'y' in display's argument? Robby On Mon, Nov 2, 2015 at 6:32 PM,

[racket-users] make-readtable with no arguments produces an incompatible readtable?

I came across some odd behavior today regarding readtables. Specifically, (make-readtable base) seems to produce a readtable that is operationally different from `base` when reading s-expression comments. Consider the following code: ; this works (read (open-input-string "(1 . 2 #;3)"))