Malcolm Wallace wrote:
Here is a strawman proposal, which does not fix the consecutive update
problem, but which might address the original typing problem.
I think it does not really address the original typing problem.
It would allow you to write:
voidcast v@(VariantWithTwo{}) = v { field1
Malcolm Wallace wrote:
voidcast :: Fields a - Fields Void
voidcast v@(VariantWithTwo{}) = v { field1 = Void , field2 = Void }
voidcast v@(VariantWithOne{}) = v { field1 = Void }
I would not expect that updating only field1 can change the type of v.
The right thing is to construct a new value.
Wolfgang Jeltsch wrote:
can anybody tell me what the German translation of the word kind as used in
type theory and especially in Haskell is?
Even Peter Thiemann in Grundlagen der funktionalen Programmierung
(1994) did not translate Kind, although he used geschönfinkelt for
curry (honoring
Christian Maeder wrote:
Geoffrey Alan Washburn wrote:
Does anyone have a prebuilt version of ghc 6.4 that works with
libreadline5? The generic Linux version on
http://www.haskell.org/ghc/download_ghc_64.html requires libreadline4,
I did not worry about the readline version and it worked
Here is my version:
-- | split list at separator elements, avoid empty sublists
splitBy :: Eq a = a - [a] - [[a]]
splitBy x xs = let (l, r) = break (==x) xs in
(if null l then [] else [l]) ++ (if null r then [] else splitBy x $
tail r)
-- suffix By usually indicates a (a - a - Bool) argument
Dimitry Golubovsky wrote:
Does there exist a generalized version of the `words' function i. e.
one that breaks an arbitrary list into parts by an arbitrary predicate?
splitAt is not what I need.
I had to write my own:
-- A version of words, but works with any lists on any predicate.
Axel Simon wrote:
Warning: retaining unknown function `getgrnam_r' in output from C compiler
I haven't overridden anything in build.mk, so I assume SplitObjs=YES.
When would I observe these warnings?
the first time when the inplace compiler translates System/Posix/Resour
ce.hs
I just see
Simon Marlow wrote:
On 10 June 2005 08:58, Serge D. Mechveliani wrote:
Now, I indeed, intend to compare 6.4 to 5.02 on several examples,
downloaded
ghc-5.02.3 and tried to make it with ghc-6.4
Yes, that's unlikely to work.
I was able to install the binaries from
Christian Maeder wrote:
6.4 produces better and faster code than 6.2.2 and 5.04.2 for our
application.
better was supposed to mean smaller binaries
___
Glasgow-haskell-users mailing list
Glasgow-haskell-users@haskell.org
http://www.haskell.org/mailman
Axel Simon wrote:
gcc -O -Wall -I../../../ghc/includes -I../../../ghc/rts
-I/core/include-c env.c -o env.p_o
cc1: /core/include: Not a directory
My gcc does not complain about that missing directory. I was able to
create a working installation under solaris with:
./configure
Serge D. Mechveliani wrote:
I used to apply FiniteMap.addListToFM.
Now, what is its best expression in ghc-6.4 ?
Is this
\ mp pairs - Map.union (Map.fromList pairs) mp
?
(the order of the arguments in Map.union is essential).
This looks fine to me. best is hard to meet. I'ld
Serge D. Mechveliani wrote:
As Jens Fisseler notes, I have made a confusion about
Set.elems, Set.toList, Set.setToList.
There is even Set.toAscList (although one may argue that should be
Set.toDistinctAscList)
I think the right choice is Set.toList (replacing setToList)
Is Set.elems just a
Mario Blazevic wrote:
mapFilter :: (a - Maybe b) - Map k a - Map k b
mapFilter f = map Maybe.fromJust . filter Maybe.isJust . map f
How about using Map.foldWithKey (and adding Ord k = to the type
signature)?
mapFilter f = Map.foldWithKey ( \ k - maybe id (Map.insert k) . f)
Map.empty
Daniel Fischer wrote:
Indeed, I have looked at the sources and found out that now the
implementations of 'Set' and 'Map' are basically the same.
The major achievement of (the new) Data.Set and Data.Map are canonical
names that should be used in conjunction with qualified imports:
import
Hi,
the following (reduced) example used to go through with ghc-6.2.2 but
fails with ghc-6.4. Which behaviour is correct? I compile with:
ghc -fglasgow-exts Context.hs
module Context where
class Language a
class Language a = Logic a b | a - b
class (Language a, Logic b c, Logic d e)
=
Hi,
I also have (a rather large) program (not included) that segfaults when
compiled with profiling. I use the ghc-6.4 linux binary distribution
from the web.
It is not even necessary to call the program with +RTS -p -RTS. There is
no problem with ghc-6.2.2, except that the old version uses its
SCOTT J. wrote:
Hi,
I use Windows XP and I like to start Ghci in extended mode. What do I have to
do in order not having to type always
:set -fglasgow-exts
under unix this line can be put in a file .ghci in your home
directory. Maybe $HOME is a variable under windows as well (and it is
Luo Shuli wrote:
Dear Haskellers,
I am a beginer of the haskell language and study it from Yet Another
Haskell Tutarial of Hal Daume III.
Example from the tutarial:
Prelude map Char.toUpper Hello World
This works only with ghci
I try it on Hugs for windows32, compile error:
ghcprof should be adapted to the new release of uDraw(Graph)
http://www.informatik.uni-bremen.de/uDrawGraph
Who maintains ghcprof? (What has cgprof to do with it?)
Christian
Simon Marlow wrote:
On 13 April 2005 14:00, Bernd Holzmüller wrote:
I am trying to create graphical profile
Wolfgang Thaller wrote:
I've uploaded a Mac OS X installer based on the stable tree from March
2nd + the patches I committed yesterday at:
http://opeongo.cas.mcmaster.ca/~wolfgang/GHC-6.4.20050302.pkg.zip
I've only a remote account on a Mac. Do I have a chance to install
ghc-6.4 locally as a
Simon Marlow wrote:
What version of gcc are you using?
I used gcc_2.95.3 until I discovered the warning:
LdvProfile.c:43: #error Please use gcc 3.0+ to compile this file with
DEBUG; gcc 3.0 miscompiles it
I've switched to gcc_3.4.3. Now the final linking of the stage2 compiler
fails (with
Hi,
we used redirect output of ghc via tee (within a Makefile). With the
new ghc this randomly fails now. Does anyone have an explanation for this?
ghc omitted args 21 | tee log
yields:
Skipping Main ( hets.hs, hets.o )
Linking ...
tee: write error
The linked binary and the log
Hi Simon and solaris GHC users,
I've made progress with ghc HEAD under solaris 8. In fact I could
successfully install a ghc-6.5 compiler that was able to compile a
couple of files (including Hello World)
But on one file (by chance HughesPJ.hs with an unqualified module name)
I got a Bus Error
This happens when partially recompiling with -O (I thing I've send a
similar bug-report that was kept in the moderator's queue because it was
to slightly too large - over 40K )
Christian
Thomas Hallgren wrote:
Hi,
I managed to distill my program into to the following small example that
still
Simon Peyton-Jones wrote:
Should be fixed now -- can you try with the HEAD?
yes, it work now! Thanks
Christian
| ghc-6.4.20050220: panic! (the `impossible' happened, GHC version
| 6.4.20050220):
| eval_data2tag
| GHCziPrim.dataToTagzh{(w) v 95f}
| @ (Bug.S{tc r14v}
Keean Schupke wrote:
There are problems with this approach...
instance (Ord a, Num a) = ApproxEq a where x ~= y = (abs (x-y) 1)
However it should do what you want with just -foverlapping-instances
-fundecidable-instances.
Only -fallow-incoherent-instances allowes to resolve
3.5 ~= 2.6
Tomasz Zielonka wrote:
Why not forget about ApproxEq for () and Bool and simply define a
function?
(~=) :: (Ord a, Num a) = a - a - Bool
x ~= y = abs (x-y) 1
Indeed, this works best. The instance for lists is also not too important.
Christian
___
[EMAIL PROTECTED] wrote:
Note that currying applies to operator sections too. The idiom of
pipelined functions deserves its own special mention:
countlines = length . lines
But this is really a shorthand for:
countlines cs = length . lines $ cs
an interesting use of $ (in conjunction with
Hi,
I've installed ghc-6.3.20050202-i386-unknown-linux.tar.bz2 only to find
out that gcc-3.4.1 seems to be hard-wired into this ghc:
ghc-6.3.20050202: could not execute: gcc-3.4.1
Why is this so. Do I need to install from sources? My current gcc
version is:
gcc (GCC) 3.3.1 (SuSE Linux)
Cheers
Simon Marlow wrote:
On 04 February 2005 12:23, Christian Maeder wrote:
ghc-6.3.20050202: could not execute: gcc-3.4.1
This is because we currently configure the nightly builds to use
gcc-3.4.1, and unfortunately that gets baked into the GHC binary. You
can compile from source to get around
our uniform workbench has a simpleDB binding to BDB.
http://www.informatik.uni-bremen.de/uniform/wb/
The sources can be downloaded with
cvs -d \
:pserver:[EMAIL PROTECTED]:/repository \
co uni
and can be compiled with a recent ghc-6.2.2.
The only documentation that I'm aware of is a
S. Alexander Jacobson wrote:
zipped =zip [1..] [1..10]::[(Int,Int)]
untup f (x,y) = f x y
produce = foldr (untup Map.insert) Map.empty zipped
fm = length $ Map.keys produce
main = print $ fm
Has this profile:
example +RTS -p -K5M -RTS
total time =5.10 secs
Hi,
in a new version of ghc I've noticed that a colon in a path (as argument
to -i) is no longer recognized. Will this also be the case in the new
version ghc-6.4?
Cheers Christian
This used to compile with ghc6.2.2:
ghc --make -v -i../DrIFT-src:../.. GenerateRules.hs
[...]
Glasgow Haskell
Henning Thielemann wrote:
What about dropping Guards? :-) Are they necessary? Do they lead to more
readable source code? Do they lead to more efficient code? I could
perfectly live without them up to now.
I hardly need guards too, but their advantage is that they let pattern
matching fail,
Derek Elkins wrote:
I find myself writing things like,
splitListOn :: Eq a = a - [a] - [[a]]
similar stuff was discussed in July 2004 on [EMAIL PROTECTED] under
the headding Prelude function suggestions, ie.
http://www.haskell.org//pipermail/libraries/2004-July/002366.html
Cheers Christian
N.B. if you want a faster answer such questions are best posted to
[EMAIL PROTECTED]
My answer: I asume that your function all_rotations somehow needs to be
called recursively for the rest of the input list xs.
Cheers Christian
imranazad wrote:
Hi,
im not very good with haskell, i barely know
The attached module does not compile and yields the following error:
InCoherentInst.hs:17:
Could not deduce (Confuse a) from the context (Typeable a)
arising from use of `breakFn' at InCoherentInst.hs:17
Probable fix:
Add (Confuse a) to the type signature(s) for
I wrote:
If, furthermore, the confusing instance is commented out, the source
even compiles without extensions.
Correction: -fglasgow-exts is still required for the type
GeneralBreakFn, but -fallow-overlapping-instances can be omitted.
{-# OPTIONS -fglasgow-exts -fallow-overlapping-instances
I've found a much shorter example (without imports) that does not
compile. The error displayed is:
Ambiguous type variable `a' in the top-level constraint:
`ATermConvertibleSML a'
arising from use of `las' at
/home/maeder/haskell/examples/NoMonoRestr.hs:29
(comenting out the initial
Christian Maeder wrote:
I've found a much shorter example (without imports) that does not
compile.
and shorter:
{-# OPTIONS -fno-monomorphism-restriction #-}
module NoMonoRestr where
data ATermTable = ATermTable
data Annotation = Annotation
data Annoted a = Annoted a [Annotation]
toPair
Use -fallow-incoherent-instances to use the first choice above)
This flag should be added to the flag reference list:
http://www.haskell.org/ghc/docs/latest/html/users_guide/flag-reference.html#AEN5847
Christian
___
Glasgow-haskell-users mailing
Simon Peyton-Jones wrote:
I'm not sure whether you are saying (a) or (b):
a) This is a compiler bug; even with -fno-monomorphism-restriction
the module should compile. Are you sure?
b) this is a feature request: you want a flag -fmonomorphism-restriction
to restore the
I wrote
| If someone wants to reproduce the error, do the following:
| 1) check out HetCATS repository with:
| cvs -d pserver:[EMAIL PROTECTED]:/repository
co
| HetCATS
| 2) comment out variable HC_PACKAGE in the Makefile (to avoid
dependency
| from uni)
| 3) add the flag
Stefan Monnier wrote:
I have recently taken over maintainership of Haskell-mode, and after making
a bunch of changes, I figured it would be a good idea to make a new release.
You can find this new release at:
http://www-perso.iro.umontreal.ca/~monnier/elisp/
Thank you!
This release has
Hi,
I've a file ATC/Sml_cats.hs that does not compile (see below) with the
flag -fno-monomorphism-restriction (ghc 6.2.2), whereas it compiles fine
without that option. Since I want to use -fno-monomorphism-restriction
for other files (from programatica) I've a problem, because there is no
Hi,
calling unlit on a DOS file fails, whereas hugs is able to process the
same file (under unix).
Christian
Prelude readFile Test.lhs = putStrLn . show
\r\n module Test where\r\n\r\n
Prelude :l Test.lhs
Test.lhs line 2: unlit: Program line next to comment
phase `Literate pre-processor' failed
deriving instances will only work for
a) known/builtin classes (like Typeable, Eq, Show, etc)
b) datatypes T that are defined elsewhere using data (or newtype) where
the corresponding deriving clause is missing.
HTH Christian
MR K P SCHUPKE wrote:
instance Typeable (T a)
Forgive my stupid
Simon Peyton-Jones wrote:
derive( Typeable (T a) )
But that means adding 'derive' as a keyword. Other possibilities:
deriving( Typeable (T a) )
-- (B) Re-use 'deriving' keyword
The trouble with (B) is that the thing inside the parens is different in this situation than in a data type
Hi,
after checking out fptools from cvs. The simple sequence
$ autoreconf
$ ./configure
$ make
failed in the directory hood, because the target boot is unknown there.
Could/Should this be fixed?
I know how to use mk/build.mk and the ProjectsToBuild variable. I don't
need hood, but make still
Simon Marlow wrote:
If you don't want to build hood, then remove it from the tree. Did you
perhaps check out *everything*? The right way is to check out fpconfig
Ah, that was my error. I checked out everything by cvs co fptools
instead of only doing cvs co fpconfig. (When I read fpconfig, I
Christian Maeder wrote:
George Russell wrote (snipped):
Now 145.
roman=(0#);a#n|n1=|n=t!!a=s!!a:a#(n-t!!a)|n+t!!b=t!!a=s!!b:a#(n+t!!b)|10=(a+1)#n
where b=2*div a 2+2;s=mdclxvi;t=[1000,500,100,50,10,5,1]
138
roman=(!6);n!a|n1=|n=t=s!!a:(n-t)!a|n+c=t=s!!(2*e):(n+c)!a|10=n!(a-1)where(d,m)=a`divMod
Graham Klyne wrote:
now 134
roman=(!6);n!a|n1=|n=t=s!!a:(n-t)!a|c=t=s!!(2*e):c!a|10=n!(a-1)where(d,m)=a`divMod`2;e=d+m-1;s=ivxlcdm;c=10^e+n;t=10^d*(1+4*m)
Doesn't that need import Array?
No, ! is user defined here (since ghc does not like # as infix)
btw, now 127:
Jorge Adriano Aires wrote:
Using the -i flag. Unfortunatly relative paths (using '~') don't seem to work,
so you have to type the full path: ghci -i/home/user/HAppS/
right '~' is not expanded, but '-i../HApps:.' should work
As far as I know, there is also no way to specify the search path in an
Christian Maeder wrote:
[EMAIL PROTECTED] - rpm -q gcc
gcc-3.3.3-41
make (in ghc-6.2.1) fails (in ghc/GC.c) with:
GC.c: In function `threadLazyBlackHole':
GC.c:4049: warning: use of cast expressions as lvalues is deprecated
make[2]: *** [GC.o] Fehler 1
The actual error not messed up by warnings
Christian Maeder wrote:
The actual error not messed up by warnings is:
../../ghc/compiler/ghc-inplace -optc-O -optc-w -optc-Wall -optc-W
-optc-Wstrict-prototypes -optc-Wmissing-prototypes
-optc-Wmissing-declarations -optc-Winline -optc-Waggregate-return
-optc-Wbad-function-cast -optc-I
I wrote:
since version 6.2 we have 2 binary distributions for (generic) linux:
for glibc 2.2 and glibc 2.3
Maybe this is no longer necessary. I've produced an installation (under
glibc 2.2) that runs under glibc 2.2 and glibc 2.3.
I've now also successfully installed ghc-6.2.1 from source under
Dear Haskellers,
since version 6.2 we have 2 binary distributions for (generic) linux:
for glibc 2.2 and glibc 2.3
Unfortunately our network has machines with both of this glibc versions.
The problem seems to be related with the inclusion of ctype.h. Is it
possible to produce a GHC binary for
Christian Maeder wrote:
since version 6.2 we have 2 binary distributions for (generic) linux:
for glibc 2.2 and glibc 2.3
Maybe this is no longer necessary. I've produced an installation (under
glibc 2.2) that runs under glibc 2.2 and glibc 2.3.
As also Volker Stolz suggested I've changed, after
We have put a large list in double quotes and used read to convert the
large literal string (too big for hugs, though) into the needed list.
This reduced compile time drastically, but I don't know how the runtime
changed. (Also errors can only occur at runtime.)
Christian
Ketil Malde wrote:
Malcolm Wallace wrote:
perhaps cond f field = if cond then f field else field
foo { bar = perhaps cond0 f (bar foo)
, wib = perhaps cond1 g (wib foo) }
I tend to write functions:
upd_bar f x = x { bar = f (bar x) }
upd_wib f x = x { wib = f (wib x) }
in order to avoid mentioning
Simon Peyton-Jones wrote:
Yes, it is, I believe. Constraints on data type declarations are a
mis-feature. I tried to get them removed, but there was some argument
that they could be made useful (see John Hughes's paper Restricted data
types in Haskell, Haskell workshop 1999), and they stayed.
Alex Gontcharov wrote:
Ignore the layout
pStack needs to be indented to the same level than digStack (or a
where must be inserted after digStack).
I can't find the error, running it gives parse error during compile on
pStack, it is not very descriptive and I don't what is wrong.
after correct
Hi,
my program throws
Stack space overflow: current size 1048576 bytes.
Use `+RTS -Ksize' to increase it.
only when translated with -O. Is it possible that the next release of
ghc uses a higher stack size at least when the -O flag is set? (Only
to reduce the likelyhood that our users need to
In a local copy of Parsec.Prim I've added:
mapState :: (st1 - st2) - State tok st1 - State tok st2
mapState f (State i p u) = State i p $ f u
mapOkReply :: (st1 - st2) - Reply tok st1 a - Reply tok st2 a
mapOkReply _ (Error a) = Error a
mapOkReply f (Ok a s e) = Ok a (mapState f s) e
mapConsumed
Koen Claessen wrote:
And instead of:
mapSet, emptySet, ...
We have:
Set.map, Set.empty, ...
This is how Chris does it in Edison.
and Daan Leijen in DData: http://www.cs.uu.nl/~daan/ddata.html
Christian
(Well, Set.map is actually missing there)
Hi,
In a local copy of Parsec.Prim I've added a primitive, that may be of
help for your problem as well.
consumeNothing :: GenParser tok st ()
consumeNothing = Parser (\state - Consumed (Ok () state (unknownError
state)))
With this I've implemented:
checkWith :: (Show a) = GenParser tok st a
The pattern [x] only matches singleton lists.
Pajo Patak wrote:
I want to return a list, from and list of lists (all integers), where
is the erroe in the code?
nthList :: [[a]] - Int - [a]
nthList ([x]:xs) 1 = [x]
nthList ([x]:xs) (n+1) = nthListh xs n
Tomasz Zielonka wrote:
On Tue, Jan 13, 2004 at 12:44:10PM +0100, Stefan Holdermans wrote:
abstract and I cannot extract the line and column numbers from a SourcePos
value. What are my options?
What about these?
sourceColumn :: SourcePos - Column
sourceLine :: SourcePos - Line
These
since GHC version 6.2.the following link is missing:
http://www.haskell.org/ghc/docs/latest/html/base/index.html
I asume that I need to change my bookmark to:
http://www.haskell.org/ghc/docs/latest/html/libraries/index.html
Cheers Christian
___
Fergus Henderson wrote:
Allowing repeated constraints would not be sufficient for that.
Yes, you're right. A true (but senseless) constraint like Show Int is
rejected as well. (The same applies to Show a if a is a scoped type
variable, that is when a is monomorph.)
So a function with type a -
Yaroslav Korchevsky wrote:
my_avg list = (accum list) / (length list)
ERROR U:\slav\FP\Avg.hs:11 - Type error in application
*** Expression : accum list / length list
*** Term : accum list
*** Type : Float
*** Does not match : Int
Why
Fergus Henderson wrote:
I think the issue here is that in ghc (with -fglasgow-exts),
the a here refers to the same type variable a in the
top of the instance declaration, which has already been
constained, and cannot be constrained again.
Is that a bug or a feature?
With Haskell 98, it is a fresh
Hi,
if I try to supply a signatur for the local function showsl below,
then ghc rejects a constraint (Show a) whereas hugs (and nhc98) needs
this constraint.
What should be the correct notation? (apart from omitting any signature)
Cheers Christian
(BTW, I would appreciate if the
I've just noticed that I used ghc with -fglasgow-exts.
Without extensions hugs, ghc und nhc98 consistently need the constraint
in the type signature (below)
showsl :: Show a = List a - ShowS
Switching the extensions on, breaks this code, however (ghc only).
Christian
I wrote:
Hi,
if I try
rui yang wrote:
I want to print a function which itself have some functions as it's parameters
and will return some functions as the results, and I want to print out the
result, does anyone knows how to define the instance declaration of show class
to this function type?
I don't know if it
Hi,
on:
http://www.haskell.org/bookshelf/
the link for: Online Haskell Course by Ralf Hinze (in German).
should be changed from:
http://www.informatik.uni-bonn.de/~ralf/teaching/HsKurs_toc.html
to:
http://www.informatik.uni-bonn.de/~ralf/teaching/Hskurs_toc.html
At least my browser seems to be
I wrote:
main=interact id basically echoes every line of my input, whereas
main=interact show correctly waits for EOF before
outputting something.
The unix cat and sort behave in a similar way (sort obviuously has
to wait for the last line.)
Still I would regard it to be more pure (or abstract)
Malcolm Wallace wrote:
[...]
Surely the name suggests that interactive behaviour is required, i.e.
exactly some interleaving of input and output. The chunk-size of the
interleaving should depend only on the strictness of the argument to
interact.
I'm not happy that interleaving depends on the
I wrote:
But looking at the two actions of interact:
interact f = do
s - getContents
putStr (f s)
I would expect the first action to be finished before the second
Keith Wansbrough wrote:
Why?
Because the actions are written down in that order? Why not? Why should
I expect pipelining?
Can actually someone supply an implementation of something like interact
that does no pipelining for the argument id? Simply doing putStr !$ f
!$ s was not enough!
Yes, of course.
Your code above only forces the evaluation of the first cons-cell of
the list, which is not enough. You want to
Hi,
For GHC (6.0.1)
main=interact id basically echoes every line of my input, whereas
main=interact show correctly waits for EOF before outputting something.
Furthermore the buffering mode must be LineBuffering.
If I explicitely set the buffering to NoBuffering I'm not able to
enter EOF by
main=interact id basically echoes every line of my input, whereas
main=interact show correctly waits for EOF before
outputting something.
Which of these are you claiming is wrong?
I guess interact does what it should, but I think it should be changed
to avoid interleaved in- and output.
lose
I wrote:
I wonder why Haskell only allows the unary minus on the left side of
an expression (lexp in the grammar).
The unary minus may also occur on the right hand side (rule: exp - lexp).
So -1 == -1 is correct, because == has lower precedence than -.
Also -1*2 is correct although it is
Brett G. Giles wrote:
Naturally, there are many great resources for this at www.haskell.org
Ensure you check out both Alex and Happy for the parsing and sourcing.
(note that Alex is currently being re-written, I'm not sure if the latest
public version has the new format/syntax)
I think, parsing
Hi,
I wonder why Haskell only allows the unary minus on the left side of an
expression (lexp in the grammar).
There should be no problem to uniquely recognize an unary minus right
beside an operation symbol (qop). Does the grammar allow two
consecutive qops in other cases?
This would allow 1
GHC tries to do so, but sometimes gets it wrong. See the
-fwarn-incomplete-patterns flag. We'd appreciate it if
someone could
overhaul this code - it's been on the wish list for a long time.
Indeed, I always try to avoid all warnings in my sources by using the
flag -Wall, because I consider
Andrew J Bromage wrote:
As a matter of interest, is there a known worst-case complexity for
the precomputation required by Earley's algorithm to handle arbitrary
CFGs?
Earley's algorithm handles exactly arbitrary (in particular ambiguous)
CFGs without precomputation.
see i.e. Aho,Ullman, The
data MyException = MkExc Int String
... but now it seems I have to install this as an instance of Typeable, and
I don't see how to do that.
instance Typeable MyException where
typeOf ? = ?
import Data.Dynamic
myExceptionTc = mkTyCon MyException
instance Typeable MyExceptionBasicSpec where
Simon Peyton-Jones wrote:
GHC 6.0 supports deriving( Typeable ), but for some strange reason it's
not in the manual. It will be.
Yes, I tried it before and gave up after a message:
../HasCASL/As.hs:24:
Can't make a derived instance of `Typeable BasicSpec'
(`Typeable' is not a derivable
Mere overload resolution (over monomorphic types) is not NP-hard. (This
is only a common misconception.)
I can only repeat my above sentence.
No, but as you note below, the interesting cases are. Most
of the more interesting number-like types are polymorphic (e.g.
Complex, Ratio).
This kind of
Andrew J Bromage wrote:
Of course you could always allow overloading _without_ requiring
module qualification (unless the overloading can't be resolved
using type information). It'd make type checking NP-hard, but I
seem to recall that it's already more complex than that.
Mere overload resolution
Hal Daume wrote:
Suppose I have:
module M1 where
import M2
foo = 'a'
and
module M2 where
import M3
and
module M3 where
foo = True
Now, inside M1, I want to write something like:
bar = if M2.foo then M1.foo else 'b'
M2 must reexport foo:
module M2 (foo) where
import M3
Johannes Waldmann wrote:
I do think that self-defined operators make a programm less readable.
I quite like most combinators from the pretty-printer or parsing libraries!
And what's absolutely horrible (IMHO) is to allow the user
to declare arbitrary precedence and associativity for his
bjkwak wrote:
I have downloaded and read some tutorials from
the Haskell home page, but most of them are
incomplete and I decided to buy a book or two.
Did you try http://www.isi.edu/~hdaume/htut/tutorial.ps ?
Yet Another Haskell Tutorial by Hal Daume III et al.
A tutorial for Haskell that is
There isn't a standard mechanism for binary I/O.
NHC98 contains the York Binary library. Can someone tell me if this is
available for other Haskell systems? And didn't GHC also provide binary I/O?
How does the GHC itself read/write binary data, since the interface
files (*.hi) produced by GHC
Hi,
whenenver I open a haskell file (*.hs) with my xemacs I get an annoying
warning in a splitted window:
(1) (error/warning) Error in `post-command-hook' (setting hook to
nil): (void-variable imenu--index-alist)
The modes (Haskell Font Ind Doc) seem to work, though.
My xemacs has [version
Sven Panne wrote:
Christian Maeder wrote:
whenenver I open a haskell file (*.hs) with my xemacs I get an annoying
warning in a splitted window:
(1) (error/warning) Error in `post-command-hook' (setting hook to
nil): (void-variable imenu--index-alist) [...]
Try adding
(require
not deeply
understanding the use of Haskell extensions in the State source,
I'm assuming Control.Monad.State's source in which case -no- extensions
are used for -State- (well, at least I don't see any quickly glancing).
Extensions are used for the -MonadState class-.
The portable parts of
The previous newtype Labeller a = Labeller (Int - (Int, a)) (the
result tuple is reversed within Control.Monad.State) would simply become
(untested):
newtype Labeller a = State Int a
newLabel = do { n - get; put (n + 1); return (Label n) }
runLabeller l = execState l minBound
it must be
I think lumping all these extensions under one switch is the
problem.
Yep, I agree. Would it be hard to split `-fglasgow-exts'
up? I'd greatly appreciate a more fine-grained control
here.
The only difficulty is that we don't have an easy way to parameterise
the parser, since it's generated from
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