Re: [racket-users] DrRacket 6.4 error message + a misleading message

Thanks for the bug report. I can confirm the error, and I will check into it tomorrow morning. > On Apr 11, 2016, at 9:25 PM, Elena Machkasova wrote: > > Hi All, > > we have discovered that in 6.4 DrRacket (Advanced Student) seems to have a > bug generating error

[racket-users] DrRacket 6.4 error message + a misleading message

Hi All, we have discovered that in 6.4 DrRacket (Advanced Student) seems to have a bug generating error messages for foldl/foldr: (foldl + (list 2 3 4) 0) gives an error message "foldl: 2th argument must be a list, given 0" (in addition to the incorrect "th" for "2nd", the 0 is actually the

Re: [racket-users] Re: What do you use macros for?

Today I decided to convert all structure definitions in a Typed Racket file to lists. For instance, (struct foo ([x : Integer])) would become a tagged list: (define-type foo (Pairof 'foo (List Integer))) along with a constructor, predicate, and accessors. Using a macro, I was able to write

Re: [racket-users] Questions about implementing a Lisp-2

Messing with `current-namespace` seems like overkill, though maybe this approach is too naive for your needs, which just involves hiding the `defun` identifiers in the current namespace with a `defun:` prefix, then using `#%app` to pull them out again. #lang racket (require rackunit

Re: [racket-users] Questions about implementing a Lisp-2

Josh Tilles wrote on 04/11/2016 07:51 PM: I'm trying to implement a Lisp-2 in Racket, I would first decide whether and how I want functions and variables provided by modules in this language, to be usable from modules in other `#lang`s. That narrows down the options of how to do it. If

[racket-users] Questions about implementing a Lisp-2

Hello Racketeers, I come seeking advice. I'm trying to implement a Lisp-2 in Racket, but I've been unsuccessful in my initial attempts. My goal is to be able to do something like the following: ``` (defun example (sym) (symbol->string sym)) (defvar example 'an-arbitrary-symbol) (example

Re: [racket-users] Re: What do you use macros for?

On Apr 12, 2016 7:53 AM, "George Neuner" wrote: > > On Mon, 11 Apr 2016 10:25:46 -0400, Matthias Felleisen > wrote: > > >These days I define little macros inside of loops or methods all the time. > > Same here. My most common uses are to handle

[racket-users] Re: What do you use macros for?

On Mon, 11 Apr 2016 10:25:46 -0400, Matthias Felleisen wrote: >These days I define little macros inside of loops or methods all the time. Same here. My most common uses are to handle database connections and to embed free form SQL into Racket code. George -- You

Re: [racket-users] Re: Problem with # and mutable lists

> > but although I changed else expresion, Racket sometimes returns same > warning(but now with #f instead of #). After you call `select-room`, you'll want to check that the result is an mlist (instead of #f or #) before calling mcdr. -- You received this message because you are subscribed to

[racket-users] Racket's UDP Behavior

I'm building reliable data transfer onto Racket's UDP suite for a term project, and I need to know what Racket does with corrupt datagrams. Since the Racket docs don't mention the word checksum for the UDP segment, I need to know some things: * Does Racket just throw away corrupt datagrams? **

Re: [racket-users] Hidden a list

You could write your own printer, that recognizes lists specially and prints them how you want, and set the `current-print` parameter. Or you could use an opaque struct type and wrap your lists with those structs. Vincent On Mon, 11 Apr 2016 10:35:55 -0500, Héctor Mc wrote: > > Hello guys, >

[racket-users] Hidden a list

Hello guys, There any way to hide the contents of a list as does the structure? (define lst (list "abc" 123 (+ 12 32))) lst ; --> '("abc" 123 44) something like # (define-struct user (nom ape)) (define u (make-user "nom" "ape")) user ; --> # u ; --> # -- You received this message because you

Re: [racket-users] Racket change button% coordinates(X and Y axis)

At Sun, 10 Apr 2016 08:18:50 -0700 (PDT), Theodor Berza wrote: > The purpose of this project is to make a GUI Builder where the user drags > buttons on a frame and the position of the cursor changes in the code the X > and Y axis. I case you haven't found it already, you might want to take a

Re: [racket-users] What do you use macros for?

Late to the party, and to make life simple, I removed all quoted material. Asumu quoted me from the early 1990s. That's what I understood back then about macros and I got on the wrong track with this idea for about five to eight years. I wanted macros to become complete language definitions