On 11/19/10 10:05 PM, Ryan Ingram wrote:
Not exactly; in the phantom type case, the two sets ARE disjoint in a
way; there are no objects that are both Foo Int and Foo Bool (although
there may be objects of type forall a. Foo a -- more on that later).
Whereas the type keyword really creates two na
On 11/19/10 10:05 PM, Ryan Ingram wrote:
On Fri, Nov 19, 2010 at 1:05 PM, Andrew Coppin wrote:
So is Either what is meant by a "sum type"?
Similarly, (X, Y) [...] is this a "product type"?
Yes and no. Unfortunately there's some discrepancy in the terminology
depending on who you ask. In the f
Multiplate is a lightweight generic library for mutually recursive data
types that won't make Conor lose his lunch.
Multiplate is an alternative extension of the Uniplate/Compos core design
to support mutually recursive datatypes in a way that is as powerful as
Compos, almost as easy to use as
On Fri, Nov 19, 2010 at 1:05 PM, Andrew Coppin
wrote:
> So is Either what is meant by a "sum type"?
> Similarly, (X, Y) [...] is this a "product type"?
Yes, and yes, although more generally speaking
data Test = A Int Bool | B Test | C [Test]
is a recursive ADT composed of sums (A ...| B... | C.
On 11/19/10 4:05 PM, Andrew Coppin wrote:
So what would happen if some crazy person decided to make the kind
system more like the type system? Or make the type system more like the
value system? Do we end up with another layer to our cake? Is it
possible to generalise it to an infinite number of
On Nov 19, 2010, at 6:00 PM, jean-christophe mincke wrote:
> Hello,
>
> Is it possible for a quasi quoter to have access to information about haskell
> identifiers declared before the quasi-quotation?
Nope. There are staging restrictions in place, since you can't sanely use
things that haven
On Nov 19, 2010, at 6:22 PM, Aaron Gray wrote:
>
> IIRC It Does not deal Hindley-Milner type system at all. i.e. it does not
> cover ML's type system.
>
> Its successor ATTAPL :-
>
> http://www.cis.upenn.edu/~bcpierce/attapl/index.html
>
> Handles an ML like type systems using constraints
There were some problems getting DPH to work well with the changes in GHC 7.
There is more info in this mail:
http://www.haskell.org/pipermail/cvs-ghc/2010-November/057574.html
The short summary is that there will be a patch level release of GHC (7.0.2)
that works well with DPH and the DPH pack
On 11/19/2010 05:24 PM, Gregory Propf wrote:
I was hoping to play around with Data.Parallel.Haskell (dph) but noticed
that it seems to have been exiled from ghc 7.0.1 which I just installed.
It also doesn't seem to be in cabal. Anybody know how to use dph with
7.0.1 or has it been abandoned or so
I was hoping to play around with Data.Parallel.Haskell (dph) but noticed that
it seems to have been exiled from ghc 7.0.1 which I just installed. It also
doesn't seem to be in cabal. Anybody know how to use dph with 7.0.1 or has it
been abandoned or something?
On 19 November 2010 22:14, Albert Y. C. Lai wrote:
> On 10-11-19 04:39 PM, Matthew Steele wrote:
>
>> TAPL is also a great book for getting up to speed on type theory:
>>
>> http://www.cis.upenn.edu/~bcpierce/tapl/
>>
>> I am no type theorist, and I nonetheless found it very approachable.
>>
>
>
Hello,
Is it possible for a quasi quoter to have access to information about
haskell identifiers declared before the quasi-quotation?
I tried the 'reify' function but without success.
Just as in the following exemple:
a = 6
x = [$expr|a|]
Where the generated haskell code is
a= 6
x = a
Thank
Hi -cafe,
I have a question about Codec.Crypto.RSA: how to enforce that
(informally) decrypt . encrypt = id
Consider this code:
encrypt2 :: String -> ByteString
encrypt2 = fst . encrypt (mkStdGen n) pubKey encode
decrypt2 :: ByteString -> String
decrypt2 = toString . decrypt privKey
Since decryp
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1
On 11/13/10 09:19 , Brent Yorgey wrote:
> On Fri, Nov 12, 2010 at 03:56:26PM -0800, Michael Litchard wrote:
>> a Perl perspective. I let him into what I was doing, and he opined I
>> should be using pcre. So now I'm second guessing my choices. Why do
>
On 10-11-19 04:39 PM, Matthew Steele wrote:
TAPL is also a great book for getting up to speed on type theory:
http://www.cis.upenn.edu/~bcpierce/tapl/
I am no type theorist, and I nonetheless found it very approachable.
TAPL is surprisingly easy-going. It is long (many pages and many
chapter
TAPL is also a great book for getting up to speed on type theory:
http://www.cis.upenn.edu/~bcpierce/tapl/
I am no type theorist, and I nonetheless found it very approachable.
I've never read TTFP; I will have to check that out. (-:
On Nov 19, 2010, at 4:31 PM, Daniel Peebles wrote:
There'
There's a lot of interesting material on this stuff if you start poking
around :) http://www.cs.kent.ac.uk/people/staff/sjt/TTFP/ might be a good
introduction.
I'd consider typeclasses to be "sets" of types, as you said, but more
generally, a relation of types. In that view, an MPTC is just an n-a
OK, so how do types actually work?
Musing on this for a moment, it seems that declaring a variable to have
a certain type constrains the possible values that the variable can
have. You could say that a type is some sort of "set", and that by
issuing a type declaration, the compiler statically
On 19/11/2010 08:32 PM, Judah Jacobson wrote:
Two possible fixes come to mind:
1) In the .cabal file for cautious-file, it says:
Flag posix
description: Use POSIX-specific features
default: True
Ah. I hadn't seen this bit.
Yes, what's probably happened is that I altered the build d
Two possible fixes come to mind:
1) In the .cabal file for cautious-file, it says:
Flag posix
description: Use POSIX-specific features
default: True
You can use "cabal install -fposix cautious-file" to explicitly turn
on POSIX support, and "cabal install -f-posix cautious-file" to
explic
On 11/19/10 12:22 PM, Andrew Coppin wrote:
Use the Force
I tried, but I'm not yet strong enough in the Force to read citations
with my eyes closed. :-(
(PS: Thanks for pointing me to the paper, Simon!)
Cheers,
Greg
___
Haskell-Cafe mailing list
Ha
On Nov 19, 2010, at 13:54, Tillmann Rendel wrote:
> Hi Bastian,
>
> Bastian Erdnüß wrote:
>> It would make my life a little bit more easy if the mailing lists on
>> haskell.org would add a Reply-To: header automatically to each
>> message containing the address of the mailing list, the message w
On 19/11/2010 08:09 PM, Simon Peyton-Jones wrote:
read the QML paper! that's the trick. simpler, but with a heavier annotation
burden than the more sophisticated approaches
Use the Force, read the... citation?
Hmm, doesn't have quite the same ring, does it?
Use the Force, read the symposium
The other day, I did a slightly foolish thing. I uttered the command
cabal install gitit
Actually, while I was "foolish", it actually worked better than you'd
think. It wanted to install several thousand billion packages, but all
of them compiled without issue.
Well, all except one. You se
read the QML paper! that's the trick. simpler, but with a heavier annotation
burden than the more sophisticated approaches
| -Original Message-
| From: Gregory Crosswhite [mailto:gcr...@phys.washington.edu]
| Sent: 19 November 2010 19:59
| To: Simon Peyton-Jones
| Cc: Haskell Cafe;
Awesome, thank you. :-) One more question out of pure curiosity, if
you have the time: What is allowing you to keep them in? I thought
that the problem was that they made a mess that touched every party of
the type checker rather than being centralized in one place. Was there
a trick you d
Yes, impredicative types are still in, but in a simpler form than before, along
the lines of QML
http://research.microsoft.com/en-us/um/people/crusso/qml/
I have been too busy with getting the new type checker working to describe or
document it. Notably, I have not yet added syntax for QML's ri
Hey everyone! I haven't had a chance to try out GHC 7 myself, but I saw
in the documentation that Impredicative Types are still supported. Is
this true? I thought that they were on their way out because they
overcomplicated type checking; has this plan been changed?
Cheers,
Greg
__
That was a great explanation of phantom types and type-families. I'm
just getting started on understand type families and I was wondering
why you didn't use data families in the truth table structure:
type family Join a b
type instance Join Safe Safe = Safe
type instance Join Safe Unsafe = Unsafe
Yes it helps, although I am no type wizard!
Thanks a lot for these insights, it gives me some more ideas.
Best regards
Arnaud
On Fri, Nov 19, 2010 at 5:55 PM, Daniel Peebles wrote:
> The "obvious" way to write the result would be (stealing some syntax made up
> by ski on #haskell):
> fromInt ::
Reply-to munging has come up many times on this list (and others).
See this page for information on why many people do not like Reply-to
munging:
http://marc.merlins.org/netrants/listreplyto.html
- jeremy
On Thu, Nov 18, 2010 at 9:55 PM, Bastian Erdnüß wrote:
> Hi there,
>
> I just put an answ
The "obvious" way to write the result would be (stealing some syntax made up
by ski on #haskell):
fromInt :: Int -> (exists n. (Nat n) *> n)
fromInt = ...
meaning, "at compile time we don't know the type of the result of fromInt,
because it depends on a runtime value, but we'll tell you it's _som
I personnally use most of the time gmail, so I don't have access to a
Reply-To-List feature (or do I?).
I usually do Reply-to-all which I think is as I guess most mailers
remove duplicate mails. Am I right?
Arnaud
On Fri, Nov 19, 2010 at 3:16 PM, Maciej Piechotka wrote:
> On Fri, 2010-11-19 at 0
On Fri, 2010-11-19 at 04:55 +0100, Bastian Erdnüß wrote:
> Hi there,
>
> I just put an answer two this in beginn...@haskell.org. It was not on
> purpose to move the topic. It's just that questions I feel I can answer are
> usually beginner level questions and so I'm not often writing in the ca
Thanks a lot for the explanation. Summarizing: You can't calculate an
exact type, but you don't care if the type of the continuation is
properly set in order to "hide" the exact type of n? Am I right?
Arnaud
On Fri, Nov 19, 2010 at 9:24 AM, Miguel Mitrofanov
wrote:
> A continuation.
>
> You can
Thank you for these excellent explanations.
Best regards,
Jerz
--
View this message in context:
http://haskell.1045720.n5.nabble.com/a-simple-question-about-types-tp3269519p3272344.html
Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.
Hi Bastian,
Bastian Erdnüß wrote:
It would make my life a little bit more easy if the mailing lists on
haskell.org would add a Reply-To: header automatically to each
message containing the address of the mailing list, the message was
sent to. Usually that's the place where others would want to
Hi
Yesterday I upgraded to the new version of hdbc-odbc (2.2.3.1.). Then I
rebuilt my own project, but the linker gives an error:
.
.
.
[88 of 90] Compiling CC ( CC.hs,
C:\eclipseworkspace_fp1\ampersand\out\CC.o )
[89 of 90] Compiling Parser ( Parser.hs,
C:\eclipseworkspa
On 11/18/2010 5:02 PM, Michael Litchard wrote:
> On Tue, Nov 16, 2010 at 4:39 PM, Michael Litchard wrote:
>> I think I may have borked things good using cygwin. I want to remove
>> it and do a clean install of haskell platform w/out cygwin. What do I
>> need to do to make sure all configuration fi
A continuation.
You can't know, what type your "fromInt n" should be, but you're not going to just leave it anyway, you're gonna do some calculations with it, resulting in something of type r. So, your calculation is
gonna be of type (forall n. Nat n => n -> r). So, if you imagine for a moment
Hi Bastian,
I generally observe the pattern that non-technical mailing lists tend to
set this header to help the user, while technical mailing list assume
(rightfully, IMHO) that the readers are fine without Reply-To. The
reasons against setting that I recall at the moment are:
* Mails meant to b
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