On Wed, 22 Dec 2010 12:23:00 -0700
Jay McCarthy
wrote:
> (require xml) does not provide any special processing functions. You
> can use normal pattern matching and functions on both the XML data
> structures and the xexpr representation. I used 'match' a lot.
>
I see. Thanks for the information
On Tue, Dec 21, 2010 at 2:20 PM, Neil Van Dyke wrote:
>
> Here's a simple example, which doesn't demonstrate all the features:
>
> (html-template
> (html (head (title "Foo & Bar"))
> (body (h1 (*value* essay-title))
> (p "Bunnies are nice." (br) "Yep."
>
...
Lo
I am just about done with the book, only a few more exercises.
The method I went at for this problem was to just set the initial position to
false and then recur on the interval.
My thinking is, to make all the spots the queen threatens on a horizontal, you
would leave the y and adjust the x.
On Wed, Dec 22, 2010 at 9:48 PM, Neil Van Dyke wrote:
> What's the status of keyword argument support in Typed Racket?
The below is still the current state, unfortunately.
> http://groups.google.com/group/plt-scheme/browse_thread/thread/2da648c872fc6d97
>
> Sam Tobin-Hochstadt wrote at Fri, 24 S
On Thu, Dec 23, 2010 at 2:26 AM, Todd O'Bryan wrote:
> I just realized something. You probably speak British (or at least
> un-American) English. One of my former students from Manchester said
> the first two weeks of math were very confusing because what we call
> parentheses he called brackets
Eli Barzilay wrote at 12/22/2010 08:04 PM:
6 minutes ago, Neil Van Dyke wrote:
Thanks for your comments, Eli. I am still wavering on whether to do the permissive
thing. And I am also looking at whether Typed Scheme and/or "html-template"
make the permissiveness less useful than before.
What's the status of keyword argument support in Typed Racket?
I found the below message from three months ago, after my Racket blew up
in the same way:
I'll have to find a way to work around this or postpone my TR adoption,
since I use keyword arguments heavily.
http://groups.google.com/gr
6 minutes ago, Neil Van Dyke wrote:
> Thanks for your comments, Eli. I am still wavering on whether to do
> the permissive thing. And I am also looking at whether Typed Scheme
> and/or "html-template" make the permissiveness less useful than
> before.
Well, the problems that I ran into wouldn't
Thanks for your comments, Eli. I am still wavering on whether to do the
permissive thing. And I am also looking at whether Typed Scheme and/or
"html-template" make the permissiveness less useful than before.
Permissiveness sure does make some things harder to implement and more
computational
DrRacket 5.0.2 isn't indenting Typed Racket "let:" forms idiomatically.
It indents them in the default way rather than a special way like it
does for Racket "let" forms.
In case anyone wants to fix this, here's how Quack currently indents
"let:" (leading space characters replaced here with ".
Yesterday, Neil Van Dyke wrote:
> Comments requested from anyone who has used SXML or xexprs...
(I didn't use either of these to a point that I could comment, but I
played with a bunch of similar things, mostly trying to get away from
the problems of the latter.)
> The extraneous list nesting in
Work around this with explicit let or other intermediate bindings:
Welcome to Racket v5.0.99.5.
> (let: ([x : Integer 5]) (ann x Real))
- : Real
5
> (let: ([x : Real 5]) (ann x Integer))
stdin::64: Type Checker: Expected Integer, but got Real in: x
Carl Eastlund
On Wed, Dec 22, 2010 at 3:54 PM,
Thanks, I'm relieved if that's a bug. Although, if it is a bug, it's a
showstopper for me until fixed, as problems like this exhibit throughout
some list-processing-intensive code I'm trying to convert to Typed Racket.
Carl Eastlund wrote at 12/22/2010 03:42 PM:
I believe your intermediate ex
I have just filed this as a bug report. Typed Racket appears to
process nested annotations in the wrong order.
Welcome to Racket v5.0.99.5.
> (ann (ann 5 Real) Integer)
- : Real
5
> (ann (ann 5 Integer) Real)
stdin::37: Type Checker: Expected Integer, but got Real in: 5
Carl Eastlund
On Wed, De
I believe your intermediate expression there, the one with two
"ann"otations in it, is a Typed Racket bug. You should definitely not
be able to take something with the type (Listof Symbol) and coerce it
to (List Symbol Symbol). For instance:
> (: f ((Listof Symbol) -> (List Symbol Symbol)))
> (d
Carl Eastlund wrote at 12/22/2010 03:06 PM:
So each time you apply cons, if you don't want a Listof type you have to
"convince" it to build something else. Do this by either annotating each step,
or binding cons with a simpler type.
Thanks for the explanation. I found that annotating eac
> I am trying to implement an is-equal? function like this:
>
> ;; is-equal? : the-obj -> boolean
> (define/public (is-equal? another-obj)
> (andmap (λ (field-name)
> (equal? (get-field field-name another-obj)
> field-name))
> (field-n
I usually use the SXML-related tools in PLaneT, rather than the "xexpr"
ones. They are a little tricky to get started with (I plan to improve
this situation soon), so here is a simple demonstration using your
example, to get you started:
Begin Example
#lang racket/base
(require (o
This works for me:
> (ann (cons 'a (ann (cons 'b '()) (List Symbol))) (List Symbol Symbol))
- : (List Symbol Symbol)
'(a b)
As does this:
> (: pair (All [X Y] (X Y -> (Pairof X Y
> (define pair cons)
> (pair 'a (pair 'b '()))
- : (List 'a 'b)
'(a b)
> (ann (pair 'a (pair 'b '())) (List Symbo
Any guidance on how to deal with constructing objects of list types
using "cons" in Typed Scheme?
Here is an illustration of one of the difficulties I'm having: trying to
produce a "(List Symbol Symbol)" using "cons"...
1. Use "cons" to produces a list of one element, annotated as different
(require xml) does not provide any special processing functions. You
can use normal pattern matching and functions on both the XML data
structures and the xexpr representation. I used 'match' a lot.
If you look on PLaneT, you will find a few processing libraries, like
an XPath implementation.
Jay
Hi there,
I'd like to know how to idiomatically handle xml using racket's xml.
Let's assume a minimal example like this:
(define xmlin "
Some software
")
(define xe (string->xexpr xmlin))
or
(define xe (xml->xexpr (document-element (read-xml (open-input-string
xmlin)
Now my
40 minutes ago, Sam Tobin-Hochstadt wrote:
> On Wed, Dec 22, 2010 at 12:36 PM, Neil Van Dyke wrote:
> > Why is ":" preferred to "define:", when usually you're just going to follow
> > the ":" form with a "define" form?
> >
> > The Typed Racket Reference says:
> >
> >> In most cases, use of ":" is
On Wed, Dec 22, 2010 at 12:52 PM, Keiko Nakata
wrote:
>> The relevant docs are in raise, with-exception-handler, and
>> uncaught-exception-handler.
>
> Can I get to know where is the source, as drracket does not navigate me?
The source for `with-handlers' and `prompt' you can find by using
check
I'm not completely sure. If drracket couldn't take me, I'd resort to
grepping ...
Robby
On Wed, Dec 22, 2010 at 11:52 AM, Keiko Nakata
wrote:
> From: Robby Findler
> Subject: Re: [racket] raise-ing an exception inside prompt
> Date: Wed, 22 Dec 2010 11:46:49 -0600
>
>> No, prompt doesn't do tha
From: Robby Findler
Subject: Re: [racket] raise-ing an exception inside prompt
Date: Wed, 22 Dec 2010 11:46:49 -0600
> No, prompt doesn't do that.
>
> This boils down to what the default uncaught-exception-handler does, which is:
>
> (abort-current-continuation (default-continuation-prompt-ta
No, prompt doesn't do that.
This boils down to what the default uncaught-exception-handler does, which is:
(abort-current-continuation (default-continuation-prompt-tag) void)
The relevant docs are in raise, with-exception-handler, and
uncaught-exception-handler.
Robby
On Wed, Dec 22, 2010 at
On Wed, Dec 22, 2010 at 12:36 PM, Neil Van Dyke wrote:
> Why is ":" preferred to "define:", when usually you're just going to follow
> the ":" form with a "define" form?
>
> The Typed Racket Reference says:
>
>> In most cases, use of ":" is preferred to use of "define:".
Two reasons:
1. Adding `
Why is ":" preferred to "define:", when usually you're just going to
follow the ":" form with a "define" form?
The Typed Racket Reference says:
In most cases, use of ":" is preferred to use of "define:".
--
http://www.neilvandyke.org/
_
For li
It looks like prompt installs its own exception handler. So the 3
gets caught and reported by prompt, which then returns a default value
of void and the call to + continues. This bears out with other
examples, such as (list (prompt (raise 3))), which returns a list
containing void.
Carl Eastlund
That's beyond me but displayln orders 'events' better here.
On Dec 22, 2010, at 12:28 PM, Keiko Nakata wrote:
> I'm not sure if I got your point, as I seem to have the same result
> after replacing with displayln.
>
> My concern is why I get a type error only for the latter?
> (And how I co
I'm not sure if I got your point, as I seem to have the same result
after replacing with displayln.
My concern is why I get a type error only for the latter?
(And how I could get both the exception and type error?)
Keiko
From: Matthias Felleisen
Subject: Re: [racket] raise-ing an exception i
Replace print with displayln. (You're buffering the output but it isn't
displayed until the repl prints the next prompt.)
On Dec 22, 2010, at 11:56 AM, Keiko Nakata wrote:
> Hello,
>
> How should I understand this behavior?
>
> (with-handlers ([(lambda (_) #t) (lambda (_) (print "exit"))])
Hello,
How should I understand this behavior?
(with-handlers ([(lambda (_) #t) (lambda (_) (print "exit"))])
(print (+ (prompt (print "hi") (raise 3) (print "bye")) 10)))
prints "hi" then "exit", whereas
(+ (prompt (print "hi") (raise 3) (print "bye")) 10)
prints "hi", then I got an uncaught
I just realized something. You probably speak British (or at least
un-American) English. One of my former students from Manchester said
the first two weeks of math were very confusing because what we call
parentheses he called brackets and what we called brackets, he called
something else.
Here's
Here's an algorithm for converting from "normal math" to Racket.
Write your expression:
people * ticket-price - (number-of-shows * 20 + people * ticket-price)
Notice that I didn't put parentheses anywhere that order of operations
didn't require them.
Now, add exactly one pair of parentheses for
On Dec 21, 2010, at 5:43 PM, Sayth Renshaw wrote:
> Do i need to define the gross function in my netpay function?
No, you don't. You've already defined it by saying
(define (gross hours)
(* hours pay-rate))
> If I have defined gross function as suggested earlier why can'
Yep.
Robby
On Tue, Dec 21, 2010 at 11:11 PM, Sayth Renshaw wrote:
>
>
> On Wed, Dec 22, 2010 at 2:04 PM, Robby Findler
> wrote:
>>
>> FWIW, if you were in my class, that solution would get few points. You
>> may have noticed people asking you about the design recipe in this
>> thread. That is a
Sayth Renshaw writes:
>
> What I am having trouble navigating is the brackets.Simply in normal math what
I am trying to do is(people * ticket price)-((number of shows * 20)+(people *
cost per person))Contrcat : total profit : attendees performance -> number;;
Purpose to calculate total profit of
What I am having trouble navigating is the brackets.
Simply in normal math what I am trying to do is
(people * ticket price)-((number of shows * 20)+(people * cost per person))
Contrcat : total profit : attendees performance -> number
;; Purpose to calculate total profit of a theatre per show
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