Thanks for this interesting example.
Just le me say up front that I regard any FD program that you cannot
translate to type families as a bug in the TF implementation. To
qualify this a little, this is definitely so for programs that do
not require undecidable instances. With undecidable
Chris Smith wrote,
ChrisK wrote:
-- You need to help GHC more here:
type instance A_T () = explicit type you actually use with ()
type instance A_T (Var x) = explicit type you actually use with (Var x)
type instance A_T [t] = t
type instance A_T (RHS (Var x) a) = explicit type you actually use
Pepe Iborra wrote,
For a taste, see Instant Insanity transliterated in this functional
language:
http://hpaste.org/2689
I thought I'd better paste here the code for Instant Insanity with Type
Families. Otherwise it will vanish in a short time.
I took the opportunity to clean it up a bit.
Derek Elkins wrote,
On Thu, 2007-09-13 at 11:12 -0700, Don Stewart wrote:
Better here means better -- a functional language on the type
system,
to type a functional language on the value level.
-- Don
For a taste, see Instant Insanity transliterated in this functional
language:
There is AngloHaskell and now AmeroHaskell. Doesn't that call for
OzHaskell?
http://haskell.org/haskellwiki/OzHaskell
Manuel
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
Call for Abstracts for 3rd SAPLING Meeting, November 12, 2007
Sydney Area Programming Language INterest Group
http://www.comp.mq.edu.au/plrg/sapling.html
10am-4:30pm, November 12, 2007
Engineering Theatre, Building 32 (Engineering)
Australian National University
Invited Speaker
Don Stewart wrote,
catamorphism:
On 10/4/07, Don Stewart [EMAIL PROTECTED] wrote:
It was raised at CUFP today that while Python has:
Python is a dynamic object-oriented programming language that can be
used for many kinds of software development. It offers strong
support for
Andrew Coppin wrote,
I've seen quite a few people do crazy things to abuse the Haskell type
system in order to perform arithmetic in types. Stuff the type system
was never ever intended to do.
Well I was just wondering... did anybody ever sit down and come up with
a type system that *is*
Dan Piponi wrote,
On 10/12/07, Brandon S. Allbery KF8NH [EMAIL PROTECTED] wrote:
He wants to write entire programs in the type system,
something like the crazies who write programs in C++ templates such
that template expansion does all the work at compile time
Crazies? :-)
Lennart Augustsson wrote,
And Haskell embedded a logical programming language on accident.
Well, we are just trying to fix that :)
On 10/15/07, *Manuel M T Chakravarty* [EMAIL PROTECTED]
mailto:[EMAIL PROTECTED] wrote:
Dan Piponi wrote,
On 10/12/07, Brandon S. Allbery KF8NH
I wrote a while ago,
There is AngloHaskell and now AmeroHaskell. Doesn't that call for
OzHaskell?
http://haskell.org/haskellwiki/OzHaskell
In the meantime a number of interested people put their name down on
the wiki page. So, let's talk more concretely about a first
meeting. I have
Ross Paterson wrote,
On Tue, Oct 16, 2007 at 10:56:27AM +1000, Manuel M T Chakravarty wrote:
Lennart Augustsson wrote,
And Haskell embedded a logical programming language on accident.
Well, we are just trying to fix that :)
Since types are inferred using unification, and classes are still
Joel Reymont:
I need to pick among the usual list of suspects for a commercial
product that I'm writing. The suspects are OCaml, Haskell and Lisp
and the product is a trading studio. My idea is to write something
like TradeStation [1] or NinjaTrader, only for the Mac.
It would be quite
Albert Lee:
I read the GHC/Data Parallel Haskell/GHC.PArr page
http://haskell.org/haskellwiki/Data_Parallel_Haskell/GHC.PArr
and make a simple test to compare the speed of PArr against List:
On the wiki page GHC.PArr is described under the heading Convenience
without the speed. You'd
1) Who's interested
Interest, yes, but time is a very scarce resource these days...
2) What dates are good
Midyear break is 29 Jun to 18 Jul at UNSW, but I'm away for a week in that time
period.
3) What projects people want to work on
To be honest, I'd probably be in and out and, on a
Hi Mihai,
A friend of mine wanted to do some Cellular Automata experiments in
Haskell and was asking me what packages/libraries are there for
multidimensional matrices. I'm interested in both immutable and
mutable ones but I don't want them to be trapped inside a monad of any
kind.
You may
This ComputerWorld (Australia) article, although about OSes, mentions
Haskell favourably:
http://www.computerworld.com.au/index.php?id=710118083
Technical detail on how Haskell helps to improve OS security is in a
recent paper:
http://www.cse.unsw.edu.au/~chak/papers/DEKC+06.html
Manuel
Brian Smith:
When using AT then we have to decide what part of the abstraction is
the class and what part is the associated type. Sometimes this seams
arbitrary. If we have:
class A a where
type B b
f :: a - B b
instance A Int where
type B = Bool
Pepe Iborra:
David Roundy droundy at darcs.net writes:
My latest attemp (which won't compile with the HEAD ghc that I just
compiled,
probably because I haven't figured out the synatax for guards with indexed
types is:
class WitnessMonad m where
type W m :: * - * - *
(=)
Hugo Pacheco:
I have recently tried to replicate some examples from in the
articles about type families but found some possible bugs.
In [2], the example
class C a where
type S a (k :: * - *) :: *
instance C [a] where
type S [a] k = (a,k a)
does not compile under the claim that the
Hugo Pacheco:
Just something I have been wondering.
I would like to implement somehting like:
type family F a :: * - *
...
class C a b where ...
instance (F a ~ F b) = C a b where ...
But apparently type equality coercions can not be used as a single
context. If I enable
Stefan Holdermans:
The problem is ambiguity. The type checker can't determine which
val function to use, i.e. which dictionary to pass to val.
I see. Still, maybe a type-error message in terms of good old
unresolved top-level overloading would be a bit more useful
here... ;-)
I agree
Hugo Pacheco:
If the equality does not hold, you should get a type error because
your program is not type correct. So, what is it that you would like
different?
I would simply like the compiler not to use that instance if the
equality constraint does not hold, like some another instance
Roman Cheplyaka:
I'm looking for interesting project to work on during Google Summer of
Code. So I found [1]A data parallel physics engine ticket and got
excited about it. I'd like to know interested mentors and community
opinion about the complexity of such project.
I have not very deep
Hi Hugo,
I have found a bug on the compiler (at least ghc 6.8.2). For some
module (yes, the example does nothing at all):
module Test where
data Type a where
Func :: Type a - Type b - Type (a - b)
PF :: Type a - Type (PF a)
data PF a where
ID :: PF (a - a)
test :: Type a - a -
Don Stewart:
I'd chime in here -- actually getting arrays and parallel arrays with
list-like interfaces, and then onto matrices, will impact a lot of
people's work, in a good way.
I am not quite sure what you mean with a list-like interface. NDP/DPH-
style arrays are exactly like Haskell
Jed Brown:
On 12 Mar 2008, [EMAIL PROTECTED] wrote:
I don't think there are a great deal of Haskell users who _really_
need a physics engine right now. However, there seem to be a massive
number who are working with matrices. I am informed that a lot of
physics is just matrix stuff underneath
Roman Leshchinskiy:
Bas van Dijk wrote:
A bit offtopic but slightly related:
I just added a GSoC project proposal about adding a nVidia CUDA
backend to Data Parallel Haskell:
http://hackage.haskell.org/trac/summer-of-code/ticket/1537
It would be great if this physics engine or matrix library
Hugo Pacheco:
Hi have tried with all versions until ghci-6.9.20080303 (from the
nightly builds), is that the one?
Yep, that one is fine.
I'm sorry but where in the darcs repo can I find it? I cannot find a
ghc-6.9 branch.
6.9 is not a branch, it is the main repository; ie,
Isto Aho:
Please, consider the example 03 of Understanding functional
dependencies
via Constraint Handling rules by Sulzmann, Duck, Peyton-Jones and
Stuckey.
There we are defining a multiplication over different numeric types:
class Mul a b c | a b - c where
(*) :: a - b - c
instance Mul
Ganesh Sittampalam:
When I try to compile this code with ghc-6.9.20080310:
module Test2 where
type family Id a
type instance Id Int = Int
type instance Id (a, b) = (Id a, Id b)
class Id a ~ ida = Foo a ida
instance Foo Int Int
instance (Foo a ida, Foo b idb) = Foo (a, b) (ida, idb)
I get
Ganesh Sittampalam:
On Mon, 17 Mar 2008, Manuel M T Chakravarty wrote:
Your are completely right. Unfortunately, superclass equalities
(ie, the Id a ~ ida in the class declaration of Foo) aren't fully
implemented yet.
OK, thanks. Is there any rough idea of when they will be?
That's
Ryan Ingram:
On 3/17/08, Hugo Pacheco [EMAIL PROTECTED] wrote:
On the other side, it fails to compile when this signature is
explicit:
fff :: forall d x. (FunctorF d) = d - F d x - F d x
fff a = fmapF a id
Interestingly, this works when you also give a type signature to id:
fff :: forall d
Claus Reinke:
type family F a :: * - *
..
We made the design choice that type functions with a higher-kinded
result type must be injective with respect to the additional
paramters. I.e. in your case:
F x y ~ F u v = F x ~ F u /\ y ~ v
i'm still trying to understand this remark:
- if we
Tom Schrijvers:
could you please help me to clear up this confusion?-)
Let me summarize :-)
The current design for type functions with result kinds other than *
(e.g. * - *) has not gotten very far yet. We are currently
stabilizing the ordinary * type functions, and writing the story up.
Claus Reinke:
type family F a :: * - *
..
We made the design choice that type functions with a higher-kinded
result type must be injective with respect to the additional
paramters. I.e. in your case:
F x y ~ F u v = F x ~ F u /\ y ~ v
actually, i don't even understand the first part of
Claus Reinke:
type family F a :: * - *
F x y ~ F u v = F x ~ F u /\ y ~ v
words, in a type term like (F Int Bool), the two parameters Int
and Bool are treated differently. Int is treated like a parameter
to a function (which is what you where expecting), whereas Bool is
treated like
Claus Reinke:
type family F a :: * - *
F x y ~ F u v = F x ~ F u /\ y ~ v
why would F x and F u have to be the same functions?
shouldn't it be sufficient for them to have the same result,
when applied to y and v, respectively?
Oh, yes, that is sufficient and exactly what is meant by F x ~ F
Manuel M T Chakravarty:
again, i gave a concrete example of how ghc behaves as i would
expect, not as that decomposition rule would suggest.
Maybe you can explain why you think so. I didn't understand why you
think the example is not following the decomposition rule.
Actually, see
Simon Peyton-Jones:
| | However, I think I now understand what you are worried about.
It is the
| | interaction of type families and GHC's generalised type synonyms
(i.e.,
| | type synonyms that may be partially applied). I agree that it
does lead
| | to an odd interaction, because the
Claus Reinke:
one might say that the central point of example two were two
partially applied type synonym families in the same position
(rhs of a type synonym family instance definition).
usually, when reduction meets typing, there is a subject reduction
theorem, stating that types do not
Claus Reinke wrote,
given that type families are never meant to be partially applied,
perhaps a different notation, avoiding confusion
with type constructor applications in favour of something
resembling products, could make that clearer?
something simple, like braces to group families and
Dan Doel:
On Tuesday 11 March 2008, Tom Schrijvers wrote:
I think you've uncovered a bug in the type checker. We made the
design
choice that type functions with a higher-kinded result type must be
injective with respect to the additional paramters. I.e. in your
case:
F x y
Hugo Pacheco:
Since I was the one to start this thread, I have managed to
implement what I initially wanted as F a :: *-* with F a x::*, and
the cost of not having partially applied type synonyms was not much
apart from some more equality coercions that I wasn't expecting.
[..]
Generally,
Simon Peyton-Jones:
| * GHC says that these constraints must be obeyed only
| *after* the programmer-written type has been normalised
| by expanding saturated type synonyms
|
...
| I regard this as a kind of pre-pass, before serious type checking
| takes place, so I don't
Hugo Pacheco:
Sorry, I meant
type FList a x = Either One (a,x)
type instance F [a] = FList a
We should not allow such programs.
Manuel
On Thu, Mar 27, 2008 at 4:45 PM, Hugo Pacheco [EMAIL PROTECTED]
wrote:
The current implementation is wrong, as it permits
type S a b = a
type
[a] = FList a
Does FList ignore its second argument? Depends on the type instances
of G.
Manuel
On Fri, Mar 28, 2008 at 12:04 AM, Manuel M T Chakravarty [EMAIL PROTECTED]
wrote:
Hugo Pacheco:
Sorry, I meant
type FList a x = Either One (a,x)
type instance F [a] = FList a
We should not allow
Henning Günther:
suppose there are two (identical) classes:
class Res a b | a - b where
getRes :: a - b
and
class Res2 t where
type Member t
getRes2 :: t - Member t
It is easy to automatically make every instance of Res2 an instance of
res:
instance Res2 a =
Hugo Pacheco:
Anyway, do you think it is feasible to have a flag such as -fallow-
unsafe-type-families for users to use at their own risk? (supposing
we know how to guarantee these constraints).
Sorry, but it doesn't seem like a good idea to enable an unsound type
system even by an
Ganesh Sittampalam:
The following program doesn't compile in latest GHC HEAD, although
it does if I remove the signature on foo'. Is this expected?
Yes, unfortunately, this is expected, although it is very
unintuitive. This is for the following reason.
Let's alpha-rename the signatures
Ganesh Sittampalam:
Can I have some advice on translating the attached Test1.hs into
type families? My attempt at doing so is in Test1a.hs, but firstly
it requires FlexibleInstances where Test1.hs didn't, and secondly it
fails because it can't infer the instance for Bar (Either Int Int)
Hi Mark,
I don't know if you have defined/studied corresponding notions of
ambiguity/coherence in your framework. Instead, I was referring to
what Manuel described as the equivalent problem using FDs:
class IdC a b | a - b
instance IdC Int Int
bar :: IdC a b = b - b
bar = id
bar' ::
apfelmus:
Manuel M T Chakravarty wrote:
Ganesh Sittampalam:
Let's alpha-rename the signatures and use explicit foralls for
clarity:
foo :: forall a. Id a - Id a
foo' :: forall b. Id b - Id b
GHC will try to match (Id a) against (Id b). As Id is a type
synonym family, it would
Ganesh Sittampalam:
On Mon, 7 Apr 2008, Manuel M T Chakravarty wrote:
Ganesh Sittampalam:
The following program doesn't compile in latest GHC HEAD, although
it does if I remove the signature on foo'. Is this expected?
Yes, unfortunately, this is expected, although it is very
unintuitive
Sittampalam, Ganesh:
Manuel Chakravarty wrote:
Ganesh Sittampalam:
On Mon, 7 Apr 2008, Manuel M T Chakravarty wrote:
Ganesh Sittampalam:
The following program doesn't compile in latest GHC HEAD, although
it does if I remove the signature on foo'. Is this expected?
Yes, unfortunately
Chaddaï Fouché:
2008/4/8, Manuel M T Chakravarty [EMAIL PROTECTED]:
You need to write the instance as
instance (b ~ TheFoo a, Foo a) = Bar (Either a b) where
bar (Left a) = foo' a
bar (Right b) = foo' (foo b :: a)
If you do that, the program compile, but res still raise a panic
Claus Reinke:
type family Id a
type instance Id Int = Int
foo :: Id a - Id a
foo = id n
foo' :: Id a - Id a
foo' = foo
type function notation is slightly misleading, as it presents
qualified polymorphic types in a form usually reserved for
unqualified polymorphic types.
rewriting foo's
Lennart Augustsson:
On Wed, Apr 9, 2008 at 8:53 AM, Martin Sulzmann [EMAIL PROTECTED]
wrote:
Lennart, you said
(It's also pretty easy to fix the problem.)
What do you mean? Easy to fix the type checker, or easy to fix the
program by inserting annotations
to guide the type checker?
apfelmus:
Manuel M T Chakravarty wrote:
apfelmus:
Manuel M T Chakravarty wrote:
Let's alpha-rename the signatures and use explicit foralls for
clarity:
foo :: forall a. Id a - Id a
foo' :: forall b. Id b - Id b
GHC will try to match (Id a) against (Id b). As Id is a type
synonym family
Lennart Augustsson:
Let's look at this example from a higher level.
Haskell is a language which allows you to write type signatures for
functions, and even encourages you to do it.
Sometimes you even have to do it. Any language feature that stops
me from writing a type signature is in my
Lennart Augustsson:
On Thu, Apr 10, 2008 at 4:20 AM, Manuel M T Chakravarty [EMAIL PROTECTED]
wrote:
the five signatures
forall a. S a
forall b. S b
forall a b. S (a, b)
Int
S Int
By alpha-convertible I mean the usual thing from lambda calculus,
they are identical modulo the names
to disbale this for certain
definitions, because you cannot give them a signature. I find that
broken.
Definitely. Can you give an example?
Manuel
On Thu, Apr 10, 2008 at 5:52 AM, Manuel M T Chakravarty [EMAIL PROTECTED]
wrote:
Lennart Augustsson:
Let's look at this example from a higher level
Lennart Augustsson:
On Thu, Apr 10, 2008 at 4:20 AM, Manuel M T Chakravarty [EMAIL PROTECTED]
wrote:
Lennart Augustsson:
On Wed, Apr 9, 2008 at 8:53 AM, Martin Sulzmann [EMAIL PROTECTED]
wrote:
Lennart, you said
(It's also pretty easy to fix the problem.)
What do you mean? Easy to fix
Dan,
I've been playing around with type families off and on in 6.8, but,
what with
the implementation therein being reportedly incomplete, it's hard to
know
what I'm getting right and wrong, or what should work but doesn't
and so on.
So, I finally decided to take the plunge and install 6.9
Peter Gavin:
Has anyone else tried implementing type-level integers using type
families?
I tried using a couple of other type level arithmetic libraries
(including type-level on Hackage) and they felt a bit clumsy to
use. I started looking at type families and realized I could pretty
Alexey Rodriguez:
We are having trouble with the following program that uses type
families:
class Blah f a where
blah :: a - T f f a
class A f where
type T f :: (* - *) - * - *
the following function does not type:
wrapper :: forall a f . Blah f a = a - T f f a
wrapper x = blah x
Alexey Rodriguez:
On Fri, Jul 4, 2008 at 5:03 AM, Manuel M T Chakravarty [EMAIL PROTECTED]
wrote:
The problem is that blah's type is ambiguous, as f does only occur
as an argument to the type family. If you'd define
class Blah f a where
blah :: a - f - T f f a
(and change the rest
Brad Larsen:
Suppose we implement type-level naturals as so:
data Zero
data Succ a
Then, we can reflect the type-level naturals into a GADT as so (not
sure if ``reflect'' is the right terminology here):
data Nat :: * - * where
Zero :: Nat Zero
Succ :: Nat a - Nat (Succ a)
Using type
Reid Barton:
On Sat, Oct 10, 2009 at 02:59:37PM -0400, Brad Larsen wrote:
Suppose we implement type-level naturals as so:
data Zero
data Succ a
Then, we can reflect the type-level naturals into a GADT as so (not
sure if ``reflect'' is the right terminology here):
data Nat :: * - * where
Lajos Nagy:
I understand that one of the original motivations for introducing
associated types to Haskell was the survey of support for generic
programming done by Garcia et al. where they compared the
implementation of the Boost Graph Library in various languages (C++,
Java, Haskell, ML,
Chris Eidhof:
I'm trying to call a Haskell function from C, on OS X. There's an
excellent post [1] by Tomáš Janoušek that explains how to do this on
Linux. However, on OS X, it's different. First of all, it looks like
the -no-hs-main flag is ignored, because I get the following error:
Tom Schrijvers wrote,
I was wondering whether there are any universities that teach about Haskell
type families or GADTs?
I do in my course Language-based Software Safety (both TFs and GADTs). It's
an advanced, research-oriented course for 4th year undergraduate and for
postgraduate
Marcus Daniels wrote,
I'm wondering if anyone has looked at OpenCL as target for Data Parallel
Haskell? Specifically, having Haskell generate CL kernels, i.e. SIMD
vector type aware C language backend, as opposed to just a Haskell
language binding.
The short answer is that there is currently
John Van Enk:
consider presenting at CUFP this year
Any word on when this will be?
It'll be before or after (I suspect the later) ICFP
http://www.icfpconference.org/icfp2010/, which is September 27-29 in
Baltimore, Maryland.
Manuel
___
Matijs Erisson:
Malcolm Wallace [EMAIL PROTECTED] writes:
... And avoid
getting screwed up by malicious folk?
... but I believe there are a number of people who regularly
review all the Recent Changes and undertake to 'undo' any
malicious/inaccurate modifications.
Neil Mitchell:
I don't think restricting editing to registered users is a significant
turn off if registration is simple.
It really really is a turn off. Sometimes when I spot a mistake, and
I'm at a computer where I haven't logged in to hawiki, I don't bother
fixing it. No one wants to
Shae Matijs Erisson:
I have a simple plan for a darcsforge as well:
If Cabal includes a darcs-repository field, developers will be able to upload
their project.cabal file to Hackage or to a darcsforge server.
That server will run darcs pull on the repositories once a night or so.
The
Cale Gibbard:
Hello, I've just started writing bindings to the Enlightenment
Foundation Libraries, using c2hs. I've run into the following problem
with the types in the foreign import declarations generated.
In Imlib2.h, there is a function prototype:
int imlib_get_visual_depth(Display *
Cale Gibbard:
On 11/12/05, Manuel M T Chakravarty [EMAIL PROTECTED] wrote:
You need to tell c2hs to what Haskell type a C pointer type maps before
it can generate the right signature for the import declaration. This is
done using a pointer hook:
http://www.cse.unsw.edu.au/~chak
Benjamin Franksen:
On Monday 12 December 2005 02:17, Manuel M T Chakravarty wrote:
The darcs version of c2hs
darcs get --partial http://www.cse.unsw.edu.au/~chak/repos/c2hs/
now permits the use of a `nocode' keyword ...
Hello
not directly related, but are there any plans to add
Bulat Ziganshin:
Hello Chris,
Sunday, March 12, 2006, 2:05:09 PM, you wrote:
CK Is GHC.PArr documented?
it's perfectly documented in module sources itself :) you can also
look at the ndpFlatten directory in ghc compiler's sources. i've
successfully used them in my program, of course
David Menendez:
This is something I've been wondering about for a while. Can you do that
sort of thing with associated types?
As another example, consider this type class for composible continuation
monads:
class Monad m = MonadCC p sk m | m - p sk where
newPrompt :: m (p
Ian Lynagh:
To fix this problem, we propose that we create a haskell.org
committee, which is responsible for answering these sorts of questions,
although for some questions they may choose to poll the community at
large if they think appropriate.
[..]
Unfortunately, this gives us a
Andrew Coppin:
On 19/11/2010 11:39 PM, David Peixotto wrote:
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
Hi Dan,
I was wondering whether anyone had any suggestions on a good way to
generate repetitive code with associated types and kind annotations.
I'd like to use TH but as far as I understand, it doesn't support this
yet (I think associated types are in HEAD but not kinds),
I implemented type
Dan:
Doesn't look like there's code out there - will try e-mailing the
authors of the various papers/presentations.
We haven't made any code available yet, but we are planning to do so
before ICFP this year.
This e-mail also counts as an open plea to those compiler wizards
working on
Lee Duhem:
On Sat, May 30, 2009 at 7:35 PM, Maurí cio briqueabra...@yahoo.com
wrote:
Hi,
How do I include type families (used as associated
types) in a module export list? E.g.:
class MyClass a where
type T a :: *
coolFunction :: Ta - a
(...)
If I just include MyClass and its
Austin Seipp:
After my last issue with GHC's HEAD, I tried checking it out again and
getting the patches for the libraries and lo and behold, it worked. So
now I'm up to date with the latest libraries and the compiler, but it
appears that building NDP itself is proving to be troublesome.
The
Don Stewart:
Haskell fans might be impressed by the good work of Joachim Breitner,
who got xmonad running on his openmoko phone,
http://www.joachim-breitner.de/blog/archives/300-Xmonad-on-my-mobile-phone.html
You can see a photo here,
Dennis Buchmann:
during my search for an acceptable development environment under
Mac OS X I found this Plugin for Xcode: http://hoovy.org/HaskellXcodePlugin/
Unfortunately, I'm not able to get it to run in Xcode v3.0 and the
developer seems
to be not contactable at the moment.
So, has
Ryan Ingram:
On Sun, Aug 31, 2008 at 7:27 PM, Jonathan Cast
[EMAIL PROTECTED] wrote:
This concept of `day-to-day work' is a curious one. Haskell is not a
mature language, and probably shouldn't ever be one.
I see where you are coming from here, but I think that train has
already started and
Miguel,
I tried to compile some code on Mac Os X (Intel) Leopard.
I have GHC 6.8.3 installed - the installer from GHC webpage
(GHC-6.8.3-i386.pkg).
But when I run make I get this error
ghc-6.8.3: could not execute: /Library/Frameworks/GHC.framework/
Versions/608/usr/lib/ghc-6.8.3/ghc-asm
I wrote a command-line program recently for a friend in haskell.
However, he's far away and not particularly computer literate. I
sent him the raw binaries, but they came up with errors about not
being able to find libgmp stuff. So then I thought I should
probably be able to somehow
Claus Reinke wrote:
Btw, is there a list of common TF pitfalls somewhere? Some example
items so far seem to be:
1 'C a = TF a', where 'a' isn't determinable
2 'TF a' is not fully polymorphic
3 'TF a' is not a decomposable type constructor, it stands only
for itself, or for its result (in that
Florian Weimer:
I can't figure out why the following code doesn't compile with the
October 2n GHC 6.10 beta (-XTypeFamilies -XFlexibleContexts) when the
type declaration is not commented out.
It's a bug that the code is accepted *without* the signature, as the
signature is ambiguous:
Corey O'Connor:
I recently had a need to use the IsFunction typeclass described by
Oleg here:
http://okmij.org/ftp/Haskell/isFunction.lhs
and am wondering if the use of the TypeCast class can be correctly
replaced by a type equality constraint.
The IsFunction and TypeCast classes were
Great! Thanks for putting the code out!
Manuel
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Claus Reinke:
What do those folks working on parallel Haskell arrays think about the
sequential Haskell array baseline performance?
You won't like the answer. We are not happy with the existing array
infrastructure and hence have our own. Roman recently extracted some
of it as a
Nicolas Frisby:
From the error below, I'm inferring that the RHS of the associated
type definition can only contain type variables from the instance
head, not the instance context. I didn't explicitly see this
restriction when reading the GHC/Type_families entry.
Could perhaps the a b - bn
Doug Ransom [EMAIL PROTECTED] wrote,
There is no need for "." or [^abc] as Haskell list operators
can be used to "simulate" them. The following is from the C
lexer and matches all visible characters and all characters
except newline, respectively:
visible = alt [' '..'\127']
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