I found these blowing down the sidewalk today
; TRUE = λx.λy.x
(define mytrue
(lambda (t) (lambda (f) t)))
and
; FALSE = λx.λy.y
(define myfalse
(lambda (t) (lambda (f) f)))
Two problems, I don't understand them and AFAICT, they don't work. I traced
them back to this
h width]
>> [height height]
>> [output filename]
>> [exists exists]))
>> (send dc start-doc "An SVG Test") ; a message
>> (send dc start-page)
>> (draw-pict p dc 0 0)
>> (send dc
I'd like to use Racket to generate scalable (svg?) graphics like gnuplot or
GeoGebra does. For example, I'd like to create a cartesian coordinate graph
system, then draw functions on it. One thing in particular would be to draw
a graph of a circle based on the standard form of a circle, e.g., x^2
Looking at HTDP-1
(http://htdp.org/2003-09-26/Book/curriculum-Z-H-25.html#node_chap_19), I see
this:
(define (filter predicate alon)
(cond
[(empty? alon) empty]
[else (cond
[(predicate (first alon))
(cons (first alon)
(filter predicate (rest
Is there a version of Racket for Android yet?
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Yes, thank you both for your help.
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I see this:
> (foldl cons '() '(1 2 3 4))
'(4 3 2 1)
and have to conclude that foldl is reversing the list. This is bolstered by
this:
(define (my-reverse lst)
(foldl cons empty lst))
which is a way of reversing a list. Good. But then I see this:
(foldl (lambda (a b result)
(begin
I'm looking at this from
https://github.com/dparpyani/99-Lisp-Problems-in-Racket:
#lang racket
(require typed/racket)
;; Question:
;; Find the last box of a list.
;;Example:
;; (my-last '(a b c d))
;; => '(d)
;; Consumes a list and returns the last element in it.
(define (my-last
This is all very impressive, indeed. I was wondering if Racket could be used to
create a new sort of GIS app, i.e., geographic information system. It would
have to do "vector graphics," which is to say every primitive drawing object is
real, i.e., isn't just a setup step toward creating a
I've seen Racket graphics doing some basic graphics. How expressive is it?
Could it do diagrams as well as TikZ or gnuplot? What output formats are there?
Could it be like Processing and do 3-d and motion?
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On Wednesday, December 14, 2016 at 12:19:51 PM UTC-5, Prabhakar Ragde wrote:
>
> I am developing such a course for a spring term (May-August) offering at
> the University of Waterloo (though it will probably use OCaml). There
> does not appear to be an ideal textbook; I plan to synthesize
Can someone suggest a good text for data structures that would compatible with
Racket? All I see are treatments using C/C++, Java, Python, i.e., the usual
suspects. Or, how do you people at Racket-friendly/based universities teach
undergrad data structures?
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I'm tackling SICP -- using Racket and Emacs/orgmode, which I think is the best
combination (YMMV). I like SICP because it puts computational math in the mix
of learning functional programming. Then Sussman did SICM (...Classical
Mechanics; 2nd edition) -- which is way over my head. But again,
On Saturday, October 29, 2016 at 3:06:18 PM UTC-4, jhemann wrote:
> Stephen's talk at 4th Racketcon (https://www.youtube.com/watch?v=SvYJF5HC19w)
> gave me a good tutorial-ish introduction.
>
>
> JBH
>
>
> On Sat, Oct 29, 2016 at 8:59 PM, Lawrence Bottorff <bor..
I see the Racket Generic Graph Library, but I don't know how to use it. Where
would one go to learn, tutorial-style" the ins and outs of using this library?
I take it this library allows you to "roll your own" graph database? I did
notice the HTDP has a section on graph things. Would this help?
I'm trying out some of the math capabilities of Racket and I'm guessing the
linear algebra concept of a vector is actually an Array type in Racket, not a
Vector. Is this correct? Racket's Vector is a data (as with Java's Vector)
structure, right?
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Just wondering if creating a module always has to be based on a .rkt file?
Would there be any way to create, say, modules (one or more) in an org-mode
file, perhaps one module per babel code block? . . . Trying to get org-mode to
be more "modular."
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So, I can start a racket REPL in Emacs geiser. Then I can type
(require typed/racket)
and it seems to take, i.e., I'm ready to go with basic typed racket. This works
as well from org-mode "babel" code blocks. Now I'd like to do the same with
plai-typed -- so I can follow along with the PLAI
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