On May 14, 2014, at 9:58 PM, Matthias Felleisen wrote:
>
> It is the season of PhD defenses, and in this spirit, it is my pleasure to
> announce that Stephen Chang successfully defended his PhD at Northeastern.
> Over the past few years, Stephen has maintained some of the stepper (with
> John
I'm teaching a junior-level algorithms course, and assigned my students to
implement three different matrix-multiplication algorithms and benchmark them.
So I had to do it myself too :-)
In untyped Racket, most of the runs took seconds or minutes, but others (only
twice as large, so I would ex
On Feb 16, 2014, at 11:38 AM, Asumu Takikawa wrote:
> On 2014-02-16 11:03:34 -0500, Asumu Takikawa wrote:
>> It would be nice if inference were smart enough so that this worked:
>>
>> (time-apply (lambda: ([x : Integer] [y : Integer]) "foo") '(1 2))
>
> I just pushed a fix to HEAD that makes t
OK, I figured out an annotation to get vector-map to work. Now I'm trying to
use time-apply, and I don't understand why it's not type-checking.
> (:print-type time-apply)
(All (b a ...) (case-> ((-> b) Null -> (values (List b) Nonnegative-Integer
Nonnegative-Integer Nonnegative-Integer))
And while I've got your attention...
When I tried the same thing with a smaller limit, e.g.
> (for/sum: : Flonum [[ii : Index 8]]
> pi)
I got not only the aforementioned complaint about Zero but also a complaint
that it expected Index, but got Byte (presumably it decided 8 was small enough
to
On Feb 13, 2014, at 2:56 PM, Vincent St-Amour wrote:
> At Thu, 13 Feb 2014 14:45:08 -0500,
> Bloch Stephen wrote:
>> Don't tell me the Zero I'm running into is the initial value of
>> for/sum's hidden accumulator
>
> Yes, that's where the Zero com
On Feb 13, 2014, at 2:51 PM, Sam Tobin-Hochstadt wrote:
>> (for/sum: : Flonum [[ii : Index 300]]
>> pi)
>>
>> and I get the type error "Expected Flonum, but got Zero". Where is there a
>> zero anywhere in this code? And even if there were a zero, shouldn't Zero
>> be a subtype of Flonum?
>>
I've removed a lot of possibly-irrelevant stuff and boiled my current obstacle
down to the following:
In #lang racket, the following works fine:
(for/sum [[ii 300]]
pi)
In #lang typed/racket, I try to do the same thing:
(for/sum: : Flonum [[ii : Index 300]]
pi)
and I get the type error
OK, I'm finally trying to teach myself some TR.
I've got a function
(: mat-cols (Mat -> Index))
that type-checks and works.
(:print-type in-range)
lists a whole bunch of cases including
(Index -> (Sequenceof Index))
So why doesn't
(for: [[colnum : Index (in-range (mat-cols m))]] do-something)
On Oct 7, 2012, at 10:03 PM, Ashley Fowler wrote:
I need help with making a function that deletes the nth term from a
list.(list LS with its Nth element (with indexes starting at 0)
deleted)
So far I have
(define (deleteNth N ls)
(if (null? ls)
ls
(deleteNth (- N 1) (cd
On Jan 3, 2012, at 1:53 PM, José Lopes wrote:
I have two files: a file "a.rkt" that defines and provides a name
to hold an image; and a file "b.rkt" that requires "a.rkt". I press
the Run button with "b.rkt" in the definitions window and I get
that I mentioned before.
I encountered a sim
On Jan 1, 2012, at 6:14 PM, Racket Noob wrote:
For all you dear academic Racket scribomans, here's a lesson from
Mark Tarver, the ingenious inventor of a new lisp-like language,
Shen (more on that beautiful language can be found here: http://
http://shenlanguage.org).
In his article "Why
On Nov 29, 2011, at 4:31 PM, David Van Horn wrote:
On 11/29/11 4:28 PM, Jakub Hadam wrote:
Hello,
I claim there is a typo in the online version of HtDP:
Exercise 4.3.3, the first condition should be
[(<= n 1000) (* .040 n)]
instead of
[(<= n 1000) (* .040 1000)]
Why? That's wha
On Nov 12, 2011, at 10:00 PM, Raoul Duke wrote:
* it seems to be serving too many different audiences out of the
box. having to choose a language is pretty confusing. is dr. racket
aimed first at top-level PLT folks who grok multi-lingual stuff? i
think that should be more ‘advanced’ and thu
I wrote:
"to-play" MIGHT be a good way to do things, but in many cases
(including the above "accelerate" example) it'll be more natural
to specify a sound as you determine the new world, rather than as
a separate function of the state of the world. It's analogous to
the difference between
On Sep 28, 2011, at 5:25 PM, Todd O'Bryan wrote:
I think that is, strangely enough, possible.
Look under the Help Desk and choose "Interact with DrRacket in
English." I can set DrRacket to Spanish even though my system is in
English. You have to restart DrRacket, but hopefully it works the sam
On Aug 31, 2011, at 10:14 PM, Shriram Krishnamurthi wrote:
HtDP: numbers first
HtDP 2/e: animations first
PP: lots of images first, animations somewhat later
To be precise, animations start in chapter 6 (out of 31). Arithmetic
starts in chapter 7 (since I have a lot of students who are ter
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