for a template-haskell splice $(derivingX)
when the compiler encounters a deriving X statement that is not built-in?
Ulf Norell wrote:
Keean Schupke [EMAIL PROTECTED] writes:
Yes, I could quite easily write the generator in TemplateHaskell (have
played with it before)
_but_ I don't like
The CVS HEAD branch of GHC seems to ignore the fixity of
type constructors imported from another module... This breaks
compiling of code that uses this feature:
module1:
type a b = a :+ b
infixr 1 :+
module2:
a :: Int :+ Float :+ Double
a = undefined
Gives a the wrong type.
Keean
obviously I meant:
type a :+ b = (a,b)
In that last post!
___
Glasgow-haskell-users mailing list
[EMAIL PROTECTED]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
The following code should compile (If the constructor
is valid, so is the function):
data Test = Test (forall a . a)
test a = Test a
However this fails to compile with the following error:
Test.hs:9:9:
Inferred type is less polymorphic than expected
Quantified type variable `a' escapes
So, does that mean that ideally we would like it to type
check, but for implementation reasons it cannot easily
be done without a type signature?
I can use the type signature no problem.
Keean.
Andres Loeh wrote:
Hi there,
The following code should compile (If the constructor
is valid, so is
Trying to recompile GHC (for the template-haskell existential support), but
keeps failing on CABAL (the import for Foreign.Marshal.Alloc is missing
from ghc/lib/compat/Distribution/Version.hs as well as import paths for
Data/Version.hi which is not compiled yet as it depends on ghc-inplace.
Some thoughts on this,
Whilst I agree that finalizers are best avoided, it must be possible to
order the finalizers for running on exit... Perhaps a simple multi-pass
algorith would do? (ie: run all finalizers that do not refer to other
objects
with finalizers - repeat until no objects with
Nope there are some unix resources that c exit routines do not free
like semaphores.
Sven Panne wrote:
Keean Schupke wrote:
[...]
Whatever happens I think it must make sure all system resources
allocated
by a program are freed on exit - otherwise the machine will have a
resource
leak
Semaphores (SYSV style) are not freed automatically. Currenly I am using
C's at_exit funtion (which is even called on a signal)... Perhaps this
is the
way to deal with foreign resources... bracket notation and at_exit to clean
up on signals?
Keean.
Sven Panne wrote:
Keean Schupke wrote:
Nope
How can I put this, it is a best efforts approach - it does its best
to run the
finalizers, even after a segmentation fault... however some of the
pointers may
be messed up... If the cleanup causes a segmentation fault (sometimes called
a double bus fault) then we have to abandon the cleanup.
I was wondering whether the method by which default types are chosen
for unresolved overloading could be made available to the programmer. It
seems
that if we consider the overlapping instances:
class x
instance Int
instance Float
instance x
x overlaps with Int and Float... I was
Simon Marlow wrote:
Note that the GC only starts the finaliser thread. The program can
still terminate before this thread has run to completion (this is one
reason why we say that finalisers don't always run before program
termination).
This sounds like a bug to me... surely you should wait
Ralf Laemmel wrote:
General conclusion:
I still have to see a good reason to use -fallow-incoherent-instances.
It's mostly good to shot yourself in the head.
Maybe one day we will get -fallow-backtracking? now that would be
useful...
Keean.
___
what about having -fno-lexically-scoped-types for old code?
Keean.
Simon Peyton-Jones wrote:
OK, OK, I yield!
This message is about lexically scoped type variables. I've gradually
become convinced that if you write
f :: [a] - [a]
f x = body
then the type variable 'a' should be
Except for GHC, where a variable staring with an '_' will not report a
warning
if it is unused in the body of a funtion:
let _ = x in y -- no warning
let result = x in y -- waring about result being unused
let _result = x in y -- no warning, but variable can still be used.
Keean.
You cannot sequence two operations from different monads...
p has type: m (IO ())
id has type, IO () (in this case because this is what p returns)...
You can do:
p :: (Monad m) = m (IO ())
p = q = (\a - return a)
Or
p :: (Monad m) = m (IO ())
p = run q = id -- provided an overloaded
Got the wrong type sig there...
p :: IO ()
p = run q = id
Keean.
___
Glasgow-haskell-users mailing list
Glasgow-haskell-users@haskell.org
http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
.
Tomasz Zielonka wrote:
On Mon, Jan 17, 2005 at 09:52:18AM +, Keean Schupke wrote:
You cannot sequence two operations from different monads...
Note that this compiles:
module Bug where
p :: IO ();
p = q = id;
q :: (Monad m) = m (IO ());
q = return (return ()); -- the only
This must be a bug then, because the following works!
y :: Num a = a
y = fromIntegral (y::Int)
A simpler example might be:
x :: Int
x = y
y :: Num a = a
y = fromIntegral x
I have not studied the report to see if this should be legal.
___
Jost Berthold wrote:
In order to force the *complete* evaluation of your result, you
could use Evaluation Strategies. Strategies are a concept
introduced for increasing parallelism in Glasgow parallel Haskell.
Parallelism and lazy evaluation are in a way contrary aims, since you
want your parallel
Jost Berthold wrote:
execution unit to do something more useful.
Yes: the compiler could do a strictness analysis and hopefully (safe
analysis)
tell wether neededList is needed by mungeForResult. In the case of
algebraic data structures (like lists), things get a bit more complex
(different
Question regarding implicit parameters... The GHC manual says:
Dynamic binding constraints behave just like other type class
constraints in that they are automatically propagated.
But the following code produces an error:
Yes, adding -fno-monomorphism-restriction allows the example to compile.
I guess I got confused by the error message, expecting it to mention the
monomorphism restriction directly... I'm sure it does sometimes. Any
chance of improving the error message for this?
Jorge Adriano Aires wrote:
Isn't it
I seem to remember that if you define the class:
class DictXMLData h = XMLData h ...
instance (Data d a,XMLNamespace a) = XMLData d where ...
then providing you annotate the instance functions with the relavent
scoped type variables (d and a) then the compiler will infer XMLNamespace
correctly for
Having looked at some of my source code this relies on Data having a
functional dependancy such that:
class Data d a | d - a ...
So it might not work for what you want.
Keean.
Keean Schupke wrote:
I seem to remember that if you define the class:
class DictXMLData h = XMLData h ...
instance
In the past having:
{-# OPTIONS -fallow-overlapping-instances #-}
in a module was enough to get ghci to allow the overlaps.
so we do:
ghci Test.hs
now it does not work (but it did in 6.3), but:
ghci -fallow-overlapping-instances Test.hs
does... Even it Test.hs is the top level module.
Keean.
with the instance decl, but it doesn't (yet). A good feature request.
Simon
| -Original Message-
| From: [EMAIL PROTECTED]
[mailto:glasgow-haskell-users-
| [EMAIL PROTECTED] On Behalf Of Keean Schupke
| Sent: 02 March 2005 17:20
| To: Simon Peyton-Jones
| Cc: glasgow-haskell-users
There can only be one top level module in ghci (there can only
be one module name before the '' prompt - that modules options
should be in effect.
The whole point of putting options at the top of the source file
is so that the user/compiler of the code does not need to know
which specific options
Simon Marlow wrote:
On 04 March 2005 12:58, Keean Schupke wrote:
There can only be one top level module in ghci (there can only
be one module name before the '' prompt - that modules options
should be in effect.
No, you can have multiple top-level module scopes in effect. See the
GHCi
Further to my last point, what if the top level module is Main...
ghci Main.hs
and that includes a main function, and pragmas, so that main runs
when ghci is finished loading (automatically).
If main runs automatically then the context of ghci must be the
Main module, so why would the options
Simon Peyton-Jones wrote:
I explained in an earlier message in this thread why the new behaviour
was an accidental consequence of lazy reporting of overlapping
instances.
So,
{-# OPTIONS -fanything except overlapping instances #-} works as expected,
only overlapping instances is affected.
I
Simon Marlow wrote:
On 04 March 2005 20:49, Keean Schupke wrote:
Further to my last point, what if the top level module is Main...
ghci Main.hs
and that includes a main function, and pragmas, so that main runs
when ghci is finished loading (automatically).
GHCi doesn't run anything
Think this should really go to glasgow-haskell-users...
If this is true - how do I get ghc to use C--, and is it really faster
than using gcc as a backend with all the bells whistles turned on (for
a pentium-III) something like
-O3 -mcpu=pentium3 -march=pentium3 -pipe -fomit-frame-pointer
Robert van Herk wrote:
Hi all,
I need to use duplicate instances. I read in the documentation on GHC
6.4, that overlapping class instances checks are lazy instead of
gready in 6.4. However, my code still gives duplicate instance errors
when compiling in GHC 6.4.
Is the duplicate instance check
Keean Schupke wrote:
Robert van Herk wrote:
Hi all,
I need to use duplicate instances. I read in the documentation on GHC
6.4, that overlapping class instances checks are lazy instead of
gready in 6.4. However, my code still gives duplicate instance errors
when compiling in GHC 6.4
There was a typo in the code I posted:
class Fail
data This_should_never_happen
should read:
class Fail x
data This_should_never_happen
Keean.
___
Glasgow-haskell-users mailing list
Glasgow-haskell-users@haskell.org
Just thought I ought to point out that all this is only necessary if the
datasources may return different types... If you want them to return the
same type you only need:
instance (Datasource l k v,Datasource r k v) = Datasource (JoinedDS l
r) k v ...
As both datasources have the same key and
Robert van Herk wrote:
Keean Schupke wrote:
Just thought I ought to point out that all this is only necessary if
the datasources may return different types... If you want them to
return the same type you only need:
instance (Datasource l k v,Datasource r k v) = Datasource (JoinedDS
l r) k v
Thought I would run some benchmarks with different compiler options, so
I pulled out some code (that compiled fine with 6.2). The code uses
MArrays to calculate a tree difference between two different XML files.
Anyway tying to compile with 6.4 I get:
ghc-6.3: panic! (the `impossible'
Robert van Herk wrote:
Sorry, this is the compiler error I get:
No instances for (KeyHasValue MyKeyVal k' v',
Datasource.Tools.FakePrelude.TypeEq Float k' z,
Datasource' z [MyKeyVal] [MyKeyVal] Float Int)
When I am trying to do
do { createJoinedDS' x x;
Some more fixes...
Keean Schupke wrote:
Hi Keean,
First of all, thank you for your answers. I have tried your solution
using TypeEq.
instance (Datasource l k' v', TypeEq k k' z, Datasource' z l r k v) =
Datasource (JoinedDS l r) k v where
_dsread (JoinedDS refl refr) k = do { l - readIORef
Not at all... You can have Datasource s k v | s k - v ... but I have't
time to do it now...
By the way that wasn't the change I was talking about!
class Datasource' z l r k v | z l r k - v
The 'z' was missing from your fundep.
Keean.
Robert van Herk wrote:
See change above!
Also note type of
In the case where a datasource is determined by 's' and 'k', we need to
return a different
type depending on sucess or failure:
data TJust t = TJust t
data TNothing = TNothing
class Datasource s k v | s k - v where
dsread :: s - k - v
instance (Datasource l k v',Datasource r k
Manuel M T Chakravarty wrote:
I accept that this is the process by which GHC computes these types, but
it does violate the principal types property, doesn't it? The relation
Int - () = forall c. Int - c
does not hold.
I realise that principal types and principal typings are slightly
Is it possible to get GCC to use the intel C compiler (ICC) instead of gcc?
Keean.
___
Glasgow-haskell-users mailing list
Glasgow-haskell-users@haskell.org
http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Sorry, yes I mean getting GHC to use ICC instead of GCC... is it just a
matter of a command line switch to give GHC the path to the compiler?
Keean.
Seth Kurtzberg wrote:
Keean Schupke wrote:
Is it possible to get GCC to use the intel C compiler (ICC) instead of gcc?
Do you mean
Picked up on this late... I have working examples of add etc under
ghc/ghci...
I can't remeber all the issues involved in getting it working, but I can
post the
code for add if its any use?
Keean.
Dirk Reckmann wrote:
Am Donnerstag, 11. August 2005 11:41 schrieb Simon Peyton-Jones:
GHCI does not load archive libraries. Is it possible (easy?) to get it
to load (.a) archive libraries as well as .o and .so files? The problem
is some optimized cblas libraries are not available as shared
libraries due to the performace loss.
Regards,
Keean.
Thaks guys... I realise it is a simple matter of unpacking the object
files, however when using ghci for prototyping, it can be more
convenient to have all the '.o's packed into a '.a'. As it is a simple
matter to extract the .o files from the .a, I would have thought a
fairly small change to
a type encompassing all the built
in types and then simply use a list of this type to achieve what you
need. Obviously the more specialised the type
you use the less cases you have to deal with, and so there is less
chance of making an error.
Regards,
Keean Schupke.
Nicolas Oury wrote
Thanks, have read the paper, however also saw the paper by Simon
Peyton-Jones and
Mark Jones on Lightweight Extensible Records for Haskell, which I think
Simon refered
to in an earlier post... would it not be better to have this instead?
Regards,
Keean Schupke.
Alastair Reid wrote
?
Regards,
Keean Schupke.
___
Glasgow-haskell-users mailing list
[EMAIL PROTECTED]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
(or a
way of setting the signal mask of the garbage collector
whilst running). Any ideas?
Regards,
Keean Schupke.
___
Glasgow-haskell-users mailing list
[EMAIL PROTECTED]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
I think if you define a default method in the class definition you will not
get this message - the default one can do nothing.
Regards,
Keean Schupke
George Russell wrote:
This isn't a bug, just a suggestion. It's not even a very important
suggestion, but one that might be worth
,
Keean Schupke.
Simon Marlow wrote:
However the problem comes when I try and use runST to run it...
runMatrix :: Array (Int,Int) Int
runMatrix = runST $ wrapper
This is becase 's' escapes
Expected: ST s a - b
Inferred: (forall s1. ST s1 a) - a
Delete the dollar?
Cheers,
Simon
in a production server, what happened - does this cause
problems in other places?
Regards,
Keean Schupke.
___
Glasgow-haskell-users mailing list
[EMAIL PROTECTED]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
(appologies if this is a repeat)
Hi,
I have also noticed the fix for DuplexHandle finalizers is not in
this release, I believe the finalizer
should be attached to the write side (which is pointed to by the read
side) but its still attached to the
read side as in previous versions... Once
handles...
Keean Schupke
___
Glasgow-haskell-users mailing list
[EMAIL PROTECTED]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
that they will (hopefully) make it into the next rev.
Keean Schupke
Simon Marlow wrote:
I have also noticed the fix for DuplexHandle finalizers is not in
this release, I believe the finalizer
should be attached to the write side (which is pointed to by the read
side) but its still attached to the
read
into an application, although
I haven't looked at the interface.
Regards,
Keean Schupke.
Carsten Schultz wrote:
Hallo,
Ghci and Template Haskell show that it is possible to compile and load
a module into a running program. Is there a user interface to do
that? Would one be possible? Would that make
Thanks, I think I was just confused... (and other types elsewhere may
have been interfearing)... there still seems
something not quite right...
If I add the following definiton to the test code:
instance Test (a - m b) (m b) where
test _ _ = Third
then I add the following print:
Erm just thought isnt this precisely where having a 'kind' definition
would be useful... so we can specify which types are valid by membersip
of a kind... (with reference to Simon PJs post about a 'kind' statement)
Playing with HsSyn types (like HsModule)... I have got down to the
definition level
Yes, I could quite easily write the generator in TemplateHaskell (have
played with it before)
_but_ I don't like the $(xxx) syntax... Perhaps if Simon could be
persuaded to allow deriving
clauses to be defined in TH?
data X x = X x
$(deriveMyClass (reify X))
could perhaps be defined from
data X
63 matches
Mail list logo
