#824: overlapping instances and separate compilation
---+
Reporter: [EMAIL PROTECTED] |Owner:
Type: bug | Status: new
Priority: normal |
On Tuesday 04 July 2006 13:20, Simon Peyton-Jones wrote:
Lexically-scoped type variables are undergoing a slight upheaval in GHC 6.6
that has not quite settled, and that is what you are running into.
Thanks for the help. After a lot of trial error, and reading and stuff I've
got past the
On Jul 11, 2006, at 11:00 AM, Simon Marlow wrote:
Which ones hang? Could you take one of the hanging tests, compile
it with -debug, run with +RTS -Ds, and send us the output?
What ends up happening is this:
28683 p2 S 0:00.11 ../../timeout/timeout 300 cd ./typecheck/
should_compile
Malcolm.Wallace:
I have a question about {-# RULES #-} pragmas. Here is a very simple
attempt to use them:
module Simplest where
{-# RULES
simplestRule forall x. id (id x) = x
#-}
myDefn = id (id 42)
I want to verify whether ghc-6.4.1 does actually fire
Does anyone have any information about the current status of Lrc?
Has it ever been released? Does it live somewhere else now?
The homepage is apparently: http://www.di.uminho.pt/~jas/Research/
LRC/lrc.html
It has a bunch of coming soon links, but the page hasn't been
updated since
hi folks,
i'm using ghc6 (apt-get install ghc6) on debian31. as far is i
understand, the following program shouldn't crash. can somebody tell me
why it does? thanks a lot. johannes.
module Main(main) where
import Control.Concurrent.STM
import System.IO.Unsafe
{-# NOINLINE a #-}
a :: TMVar
On 7/11/06, Johannes Goetz [EMAIL PROTECTED] wrote:
i'm using ghc6 (apt-get install ghc6) on debian31. as far is i
understand, the following program shouldn't crash. can somebody tell me
why it does? thanks a lot. johannes.
Because atomically doesn't like unsafePerformIO.
For TVars there's
On 7/12/06, Taral [EMAIL PROTECTED] wrote:
Because atomically doesn't like unsafePerformIO.
In more detail: atomically is not re-entrant. You could try something like:
main = a `seq` do ...
to make sure that you don't re-enter the STM subsystem and crash.
--
Taral [EMAIL PROTECTED]
You
Hello Haskell,
one Streams library user asked me about support of serialization
TOGETHER with type information which means implementation of
instance Binary Data (any other variants?). can anyone describe me
how i can implement this? Binary instance is very like Show/Read, just
uses compact
Quoth John Meacham [EMAIL PROTECTED]:
...
| just a note: I find splitBy a much nicer routine to provide.
|
| splitBy :: (a - Bool) -- ^ whether char is a separator
| - [a] -- ^ list to split
| - [[a]]
Starting from the assumption that in most cases the list to be split
will be
I don't see how this can work for arbitrary types without auto-
generating the serialization code. Once the code is generated you can
just store the type dictionary at the beginning of the file and use
it to deserialize.
I'm not sure this can be done on top of Binary since the type tag
John Meacham schrieb:
just a note: I find splitBy a much nicer routine to provide.
I would support this, if it helped to find a consensus. It's more
difficult to decide if empty lists as elements of the result list (at
the beginning, at the end or in the middle) should be returned. I would
say
Hi,
I can do this:
(let a=3 in a) + (let b=4 in b)
but not this:
(a where a=3) + (b where b=3)
Why?
Thanks,
Maurício
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Mauricio,
The let variant is an expression, while the where one is not. An
expression is allowed to happen inside a greater expression, you just
need to place the parentheres properly as you did.
The where keyword does not construct a valid expression, it can only
happen inside some other
By the way, you can find the syntax specification here
http://haskell.org/onlinereport/syntax-iso.html
Regards,
Thiago Arrais
--
Mergulhando no Caos - http://thiagoarrais.blogspot.com
Pensamentos, idéias e devaneios sobre desenvolvimento de software e
tecnologia em geral
On 7/10/06, Fritz Ruehr [EMAIL PROTECTED] wrote:
Were you interested in seeing the function, you could do so, at least
for finite, total functions (you can also enumerate them, compare them
for equality, etc.). See my haskell-cafe message at
Hello Haskell,
what is a best way to bring C constant (defined in header file) into
the Haskell source? Haskell project is cabalized and should work with
both Win and Unix while the constants are OS-specific. the best way i
found at this moment is to use the following scheme:
mmap.h:
#if
Hello Maurício,
Tuesday, July 11, 2006, 5:34:58 PM, you wrote:
Hi,
I can do this:
(let a=3 in a) + (let b=4 in b)
but not this:
(a where a=3) + (b where b=3)
Why?
'where' is a part of function definition syntax, while 'let .. in ..'
is just an expression like 'if ...' or
Brief disclaimer: I'm using GHC 6.4.1 and haven't looked into Hugs; but I
don't suspect there's much difference on this issue. Could easily be
wrong there.
I've hit a bit of a road bump in ambiguity regarding type class
instances and transformer types (in the style of monad transformers).
The
Johan == Johan Grönqvist [EMAIL PROTECTED] writes:
Johan I am a haskell-beginner and I wish to write a Forth-like
Johan interpreter. (Only for practice, no usefulness.)
Johan I would like use a list (as stack) that can contain several
Johan kinds of values.
Johan data Element = Int Int | Float
Bulat == Bulat Ziganshin [EMAIL PROTECTED] writes:
Bulat Hello Haskell, what is a best way to bring C constant (defined
Bulat in header file) into the Haskell source? Haskell project is
Bulat cabalized and should work with both Win and Unix while the
Bulat constants are OS-specific. the best way
Hello,
I was planning to create FFI bindings for GHC to be able to use
comdlg32.dll and I just realized I should ask if others have already
done this.
I figure I'll probably just code it up by hand assuming I can find
suitable documentation but if there is a tool that can generate this
At Tue, 11 Jul 2006 19:28:13 +0400,
Bulat Ziganshin wrote:
Hello Haskell,
what is a best way to bring C constant (defined in header file) into
the Haskell source?
If this ^^^ was your entire question, I would say, use hsc2hs.
splitBy :: (a - Bool) -- ^ whether element is a seperator
- [a] -- ^ list to split
- [[a]]
P.S. inspecting more than one element looks like an over-generalization
to me and should be left to parsers or regexp libs.
It's more generally useful if you don't drop the separators
Hi,
There is a Win32 package which is shipped with WinHugs (and perhaps
GHC as well). That may have the comdlg32.dll stuff in it, and if it
doesn't that would be the place to add it, and it probably gives a
good example of how to add it.
Thanks
Neil
On 7/11/06, Jason Dagit [EMAIL PROTECTED]
I personally use
split :: Eq a = [a] - [a] - [[a]]
all the time, much more often than
splitBy :: (a - Bool) - [a] - [[a]]
But I don't call it split. By analogy with
concatMap, the Haskell analogue of Perl/Python
join is concatIntersperse. Then, by analogy
with lines/unlines, the Haskell
split is... unconcatIntersperse.
How about separate? (split or splitBy is better but it is used
all over the place in many libs)
And for strings I definitely would use split :: [a] - [a] - [[a]] a
lot, just like Python's split function. And words works great for
breaking on multiple spaces,
On Jul 11, 2006, at 8:27 AM, ihope wrote:
On 7/10/06, Fritz Ruehr [EMAIL PROTECTED] wrote:
Were you interested in seeing the function, you could do so, at
least
for finite, total functions (you can also enumerate them, compare them
for equality, etc.). See my haskell-cafe message at
I'm trying to translate this HXT code to use the Arrow 'do' syntax:readWriteDoc :: String - IOSLA (XIOState s) b IntreadWriteDoc path = readDocument [(a_validate, 0)] path
writeDocument [(a_output_encoding, isoLatin1)] -
getErrStatusThis attempt fails to compile:
readWriteDoc :: String -
On 7/11/06, Neil Mitchell [EMAIL PROTECTED] wrote:
Hi,
There is a Win32 package which is shipped with WinHugs (and perhaps
GHC as well). That may have the comdlg32.dll stuff in it, and if it
doesn't that would be the place to add it, and it probably gives a
good example of how to add it.
The
Hi Jason,
On 7/12/06, Jason Dagit [EMAIL PROTECTED] wrote:
The package you mention appears to ship with visual haskell but I
don't see any wrappers for the functionality in comdlg32.dll. I would
like to add that functionality. Do you know where I can find the
source code for this package?
Hello.
I'm currently using Data.Graph.Inductive to represent a directed graph.
I want to detect all cycles within the graph and 'break' them by inserting a
minimal number of nodes that are labelled with a special cycle-breaker label.
Can anyone give me advice on a good algorithm for finding
Nicolas Frisby posed a problem about controlling the order of
instance selection rules (or, the application of type improvement rules)
Given the following code
newtype IdL a = IdL a
newtype IdR a = IdR a
class C f g where nest :: f a - g a
instance C IdL IdR where nest (IdL x) = IdR x
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