RE: hsc crashes when compiling GHC 4.06 sources
I downloaded the sources from GHC 4.06, made the shallow tree, added a build.mk in mk/ with -H80, later with -H80 -O2, made ./configure in ghc/ and ./configure in the main tree, (copied both .y files because happy doesn't work on links done with lndir -- it's only NT), said make boot and then [ blah blah blah *crash* ] This is just a guess, and Sigbjorn or Reuben might be able to provide more information, but try compiling the compiler with '-static'. Cheers, Simon
Re: gmp configure (fwd)
Reuben Thomas wrote: I already came across this, and Sigbjørn sent me a fix, which should soon be in CVS. Just in case it's not, it follows below. I found that I also needed to change rts/gmp/configure.in so that the first call to AC_INIT occurred after the setting of the three variables just below it. anoncvs version still doesn't work, though at least it doesn't loop forever. After regenerating the new gmp configure file I get: gmake[1]: Entering directory `/usr/local/pub-bkb/ghc/fptools/ghc/rts/gmp' /bin/sh ./config.status configure: error: --norecursion: invalid option; use --help to show usage
RE: gmp configure (fwd)
Reuben Thomas wrote: I already came across this, and Sigbjørn sent me a fix, which should soon be in CVS. Just in case it's not, it follows below. I found that I also needed to change rts/gmp/configure.in so that the first call to AC_INIT occurred after the setting of the three variables just below it. anoncvs version still doesn't work, though at least it doesn't loop forever. After regenerating the new gmp configure file I get: gmake[1]: Entering directory `/usr/local/pub-bkb/ghc/fptools/ghc/rts/gmp' /bin/sh ./config.status configure: error: --norecursion: invalid option; use --help to show usage What version of autoconf is this, just out of interest? Simon
Re: gmp configure (fwd)
Simon Marlow wrote: What version of autoconf is this, just out of interest? autoconf --version Autoconf version 2.13 Oh no, don't tell me I've got to install a private copy of yet another bit of software to compile GHC . . .
RE: gmp configure (fwd)
Simon Marlow wrote: What version of autoconf is this, just out of interest? autoconf --version Autoconf version 2.13 Oh no, don't tell me I've got to install a private copy of yet another bit of software to compile GHC . . . It builds fine for me here with autoconf 2.13 on Solaris. Perhaps you have some old configure files lying around in ghc/rts/gmp/*. Try blowing away your gmp subtree and starting again. It may not work with old versions of autoconf (pre-2.12 ???) anymore, but I don't have any around to try. Cheers, Simon
Re: gmp configure (fwd)
Simon Marlow wrote: It builds fine for me here with autoconf 2.13 on Solaris. Perhaps you have some old configure files lying around in ghc/rts/gmp/*. Try blowing away your gmp subtree and starting again. After deleting the whole of ghc, rerunning autoconf several times (why isn't this done by gmake -f Makefile.config?), and ./configure several more times I can now do gmake clean again.
RE: gmp configure (fwd)
Simon Marlow wrote: It builds fine for me here with autoconf 2.13 on Solaris. Perhaps you have some old configure files lying around in ghc/rts/gmp/*. Try blowing away your gmp subtree and starting again. After deleting the whole of ghc, rerunning autoconf several times (why isn't this done by gmake -f Makefile.config?), and ./configure several more times I can now do gmake clean again. I'm not sure why you need to run these things several times. Makefile.config can build the configure script in fptools, if needs be. It doesn't build any of the other configure scripts because the top-level fptools is supposed to be independent of the packages (ghc,happy,hdirect etc.) actually installed. Cheers, Simon
VTALRM and System.system
More through testing of my quick fix (ie trying bigger examples)
revealed that my "trap '' 26" hack failed about 1% of the time.
This being too often (approximately once per program run!)
I hacked up fptools/ghc/lib/std/cbits/system.c by adding this code
case 0:
/* the child */
#ifdef ADR_HACK
block_vtalrm_signal(); /* from rts/ITimer.c */
#endif
execl("/bin/sh", "sh", "-c", cmd, NULL);
_exit(127);
}
Compiled it using this make entry
RTS = /z/reid/tmp/fptools
system.o: system.c
$(CC) -DADR_HACK=1 -I$(RTS)/mk/config.h -I$(RTS)/ghc/includes
-I$(RTS)/ghc/lib/std/cbits system.c -c
And added system.o to my link line.
Initial testing suggests that it fixes the problem.
A
The return of the Void [Was: newtypes]
On Thu, 16 Mar 2000, Chris Okasaki wrote:
newtype Foo = F Foo
Interesting loop hole you found there! Semantically it should be pretty
clear what this type means, just as the corresponding meaning on the
value level:
bottom = bottom
Foo is simply Void! (formal def. later)
Void has been in Haskell, I can't really remember why it had to go - well
here it is again anyway!
Admittedly, you could never construct a value of these
types, but, even so, what do these types mean?
Sure you can - as all Haskell types it contains bottom (as defined
above) and for example
void = Void void
which is just another way of defining bottom :: Void.
Semantically the meaning is the least fixed point of the identity functor,
that is the minimal CPO containing only _|_.
Hugs and hbc accept it without complaining. (I haven't got nhc installed.)
What is interesting is that ghc loops when trying to compile this
definition! (Ghc folks, consider this a bug report, details below!)
Patrik Jansson
-- Some examples - all run in hugs and hbc
newtype Void = Void Void deriving Show
void :: Void
void = Void void
bottom :: a
bottom = bottom
newtype A = MkA B deriving Show
newtype B = MkB A deriving Show
a = MkA b
b = MkB a
bot_a = bot_b
bot_b = bot_a
newtype Stream a = C (a,Stream a) deriving Show
scons :: a - Stream a - Stream a
scons x xs = C (x,xs)
ones :: Stream Int
ones = scons 1 ones
newtype List a = L (Either () (a,List a)) deriving Show
nil :: List a
nil = L (Left ())
cons :: a - List a - List a
cons x xs = L (Right (x,xs))
toList :: [a] - List a
toList = foldr cons nil
main = print void
===
minimal test case for ghc
cat newtype.hs __END__
newtype Void = Void Void
main = print ()
__END__
And the output from ghc -v newtype.hs: [Unfortunate line breaks by my
mailer]
The Glorious Glasgow Haskell Compilation System, version 4.06
Effective command line: -v
Ineffective C pre-processor:
echo '{-# LINE 1 "newtype.hs" -}' /tmp/ghc779.cpp cat
newtype.hs /tmp/ghc779.cpp
0.00user 0.00system 0:00.01elapsed 0%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (105major+14minor)pagefaults 0swaps
ghc:compile:Output file newtype.o doesn't exist
ghc:compile:Interface file newtype.hi doesn't exist
ghc:recompile:Input file newtype.hs newer than newtype.o
Haskell compiler:
/usr/lib/ghc-4.06/ghc-4.06/hsc /tmp/ghc779.cpp
-fignore-interface-pragmas -fomit-interface-pragmas -fsimplify [
-fmax-simplifier-iterations4 ] -fwarn-overlapping-patterns
-fwarn-missing-methods -fwarn-missing-fields -fwarn-duplicate-exports
-fhi-version=406 -static
"-himap=.%.hi:/usr/lib/ghc-4.06/ghc-4.06/imports/std%.hi" "-himap-sep=:"-v
-hifile=/tmp/ghc779.hi -C=/tmp/ghc779.hc -F=/tmp/ghc779_stb.c
-FH=/tmp/ghc779_stb.h +RTS -H600 -K100
Glasgow Haskell Compiler, version 4.06, for Haskell 98, compiled by GHC
version 4.06
[ Time passes, eventually I press Ctrl-C ]
Command exited with non-zero status 252
89.31user 0.16system 1:30.49elapsed 98%CPU (0avgtext+0avgdata
0maxresident)k
0inputs+0outputs (1330major+1772minor)pagefaults 0swaps
deleting... /tmp/ghc779.cpp /tmp/ghc779.hi /tmp/ghc779.hc
/tmp/ghc779_stb.c /tmp/ghc779_stb.h
rm -f /tmp/ghc779*
Re: Recent Sparc breakage
[Me reporting: Integer artithmetic broken.] [Simon Marlow reporting: Integer arithmetic possibly fixed.] Hello again, It has taken me 8 days to rebuild ghs from cvs after this report. Unfortunately I have to report thast the Integer arithmetic is still broken. Pleases feel free to contact me for further info:. Regards, Marc van Dongen
RE: default alternatives in STG
Right. There's a binder in the case instead. We write it like htis
case e of x {
C a b - ...x...
DEFAULT - ...x...
In both alteratives, x is bound to the value of e.
In the first alternative, the value of e is certainly (C a b).
In the second alternative, we only know that x is *not* bound to (C _ _);
it must be some other constructor for the type.
Does that help?
S
| -Original Message-
| From: Kwanghoon Choi [mailto:[EMAIL PROTECTED]]
| Sent: 16 March 2000 11:09
| To: [EMAIL PROTECTED]
| Subject: default alternatives in STG
|
|
|
| Hello,
|
| In GHC4.06, the syntax of STG seems to be changed not to include
| default alternatives in the form of ``var - expr''. It includes
| only the form of ``default - expr''. Right?
|
| Thanks.
|
| Kwanghoon Choi
|
|
|
Re: newtypes
"S.M.Kahrs" wrote: newtype Inftype b = A (b,Inftype) newtype Alist a = B (Either () (a,Alist a)) infy = A (1,infy) onetwothree = B (Right(1,B(Right(2,B(Right(3,Left ())) The following works with hugs. newtype Inftype b = A (b,Inftype b) newtype Alist a = B (Either () (a,Alist a)) infy = A (1,infy) onetwothree = B (Right(1,B(Right(2,B(Right(3,B(Left (
Re: docbook tools (was ghc-4.06-1.src.rpm)
On Wed, Mar 15, 2000 at 10:27:56AM +, Peter Hancock wrote: After a _lot_ of ferreting round the net, I found db2dvi in stylesheets-0.10-2.i386.rpm. (Actually, it's not in docbook-3.1-5.i386.rpm, or psgml-1.2.1-1.i386.rpm, or sgml-tools-1.0.9-5.i386.rpm, or jade-1.2.1-9.i386.rpm, or ...) The adjective `exotic' seems apt. (By the way, the docbook web page says that the project has been suspended.) Surely you mean the sgmltools webpage? These tools, for the linuxdoc sgml DTD, are being replaced (for the purpose of the Linux Documentation Project at least) by some new ones for the docbook sgml DTD. See http://www.linuxdoc.org for the latest on this. Greg O'Keefe
Re: ghc-4.06-1.src.rpm
Tue, 14 Mar 2000 13:54:49 + (GMT), [EMAIL PROTECTED] [EMAIL PROTECTED] pisze:
I have heard that rpm version 3 now contains a way to specify
build-time requirements (as distinct from install-time).
Yes, "BuildRequires:".
Is it sufficient to describe the bootstrapping of self-compiling
compilers?
If it requires a binary version of itself installed to be compiled,
then it makes sense to specify it in BuildRequires.
--
__("Marcin Kowalczyk * [EMAIL PROTECTED] http://qrczak.ids.net.pl/
\__/ GCS/M d- s+:-- a22 C+++$ UL++$ P+++ L++$ E-
^^ W++ N+++ o? K? w(---) O? M- V? PS-- PE++ Y? PGP+ t
QRCZAK 5? X- R tv-- b+++ DI D- G+ e h! r--%++ y-
Re: records in Haskell
Simon Marlow wrote:
Jan Kort writes:
It seem that any record, no matter how trivial, can't be much
longer than about 200 lines in Haskell. If a try to compile a
300 line record containing just:
data X = X {
f1 :: String,
f2 :: String,
f3 :: String,
...
f300 :: String
}
It needs about 90M heap in ghc4.06. Whereas a 150 line record
requires less than 6M heap. After this big gap it levels off
to a somewhat more decent exponential increase: a 450 line
record requires about 180M heap.
I could file a bug report, but it seems that all compilers
(ghc4.06, nhc98, hbc0.9994 and hugs) have this problem. So,
is this a fundamental problem ?
Actually, the 150-line record needs about 20M, and the 300-line record needs
about 75M. These figures are roughly double the actual residency, because
GHC's underlying collector is a copying, not compacting, one.
GHC automatically increases the heap size up to a maximum of 64M unless you
tell it not to (with -optCrts-M32m, for example). I'll bet this is the
source of the confusion.
The heap requirement is still non-linear, but I'm guessing that this is
because for each line you add to the record the compiler has to not only
generate a new selector function, but also add a field to the record being
pattern matched against in all the existing selectors.
Cheers,
Simon
Thanks for the answers and sorry for the late reaction.
I worked out an example to understand what you wrote.
GHC will probably generate something like this:
data R = R String Integer
deriving (Read,Show)
selectA (R s _) = s
selectB (R _ i) = i
updateA (R _ b) a = (R a b)
updateB (R a _) b = (R a b)
emptyR = R undefined undefined
Which you can then use like this:
updateR = updateB (updateA emptyR "a") 2
testA = selectA updateR
testB = selectB updateR
I agree that the select and update pattern matchings would
get big for a 300 line record, but 75M is a lot of memory.
Especialy because the pattern matches and the right hand
sides of both the selects and updates are trivial pieces
of code: no nesting, no currying etc. But maybe GHC
generates something extra ? Is special code generated
for updating multiple fields for example ?
I can probably work around this in a simple way: since I'm
generating the big record, I might as well generate
the selects, updates and emptyR instead and split them
over a couple of files.
Jan
speed and size of compiled Haskell code
Hi, I wonder if someone could tell me more about the speed and size of compiled Haskell code. E.g. if one uses GHC to compile Haskell code into native code what speed performance can be expected versus a same program written in C (Hints about the nhc compiler are welcome). Is lazyness as good as strictness. What about Haskell 98 versus (I anticipate) Haskell 2 Thanks Jan Brosius
Re: records in Haskell
Does anyone know if this below situation is as bad in say SMLNJ or OCAML?
JanBrosius
- Original Message -
From: Jan Kort [EMAIL PROTECTED]
To: Simon Marlow [EMAIL PROTECTED]
Cc: [EMAIL PROTECTED]
Sent: Thursday, March 16, 2000 12:59 PM
Subject: Re: records in Haskell
Simon Marlow wrote:
Jan Kort writes:
It seem that any record, no matter how trivial, can't be much
longer than about 200 lines in Haskell. If a try to compile a
300 line record containing just:
data X = X {
f1 :: String,
f2 :: String,
f3 :: String,
...
f300 :: String
}
It needs about 90M heap in ghc4.06. Whereas a 150 line record
requires less than 6M heap. After this big gap it levels off
to a somewhat more decent exponential increase: a 450 line
record requires about 180M heap.
I could file a bug report, but it seems that all compilers
(ghc4.06, nhc98, hbc0.9994 and hugs) have this problem. So,
is this a fundamental problem ?
Actually, the 150-line record needs about 20M, and the 300-line record
needs
about 75M. These figures are roughly double the actual residency,
because
GHC's underlying collector is a copying, not compacting, one.
GHC automatically increases the heap size up to a maximum of 64M unless
you
tell it not to (with -optCrts-M32m, for example). I'll bet this is the
source of the confusion.
The heap requirement is still non-linear, but I'm guessing that this is
because for each line you add to the record the compiler has to not only
generate a new selector function, but also add a field to the record
being
pattern matched against in all the existing selectors.
Cheers,
Simon
Thanks for the answers and sorry for the late reaction.
I worked out an example to understand what you wrote.
GHC will probably generate something like this:
data R = R String Integer
deriving (Read,Show)
selectA (R s _) = s
selectB (R _ i) = i
updateA (R _ b) a = (R a b)
updateB (R a _) b = (R a b)
emptyR = R undefined undefined
Which you can then use like this:
updateR = updateB (updateA emptyR "a") 2
testA = selectA updateR
testB = selectB updateR
I agree that the select and update pattern matchings would
get big for a 300 line record, but 75M is a lot of memory.
Especialy because the pattern matches and the right hand
sides of both the selects and updates are trivial pieces
of code: no nesting, no currying etc. But maybe GHC
generates something extra ? Is special code generated
for updating multiple fields for example ?
I can probably work around this in a simple way: since I'm
generating the big record, I might as well generate
the selects, updates and emptyR instead and split them
over a couple of files.
Jan
FW: speed and size of compiled Haskell code
Jan's questions I don't think have a simple answer. My own belief is that with sufficient development effort, one can always write a C program that is more efficient than compiled Haskell code. However, the same thing also applies to assembly language. The question, imho, is what are the typical efficiency-vs-development-effort curves for C and haskell. I think problems that are conceptually simple, but require large volumes of similar data, may surpass haskell at all levels of development effort. My own experience suggests that for problems which require more intelligence and less sheer volume of data, a haskell solution can require an order of magnitude less development effort. I think the folks working with Frob and Fran would say something similar. Only when the development effort is exceedingly high, in these cases, would C be more efficient. However, even in those cases, the following steps might provide the best results. 1) Code in Haskell 2) Search for optimizations in Haskell 3) Search for bottlenecks that could be reduced by re-writing some part of the code in C 4) If efficiency requirements are still not met, use the above code as a prototype and recode in C I hope this gives you a place to start. -Original Message- From: Jan Brosius [mailto:[EMAIL PROTECTED]] Sent: Thursday, March 16, 2000 8:04 AM To: [EMAIL PROTECTED] Subject: speed and size of compiled Haskell code Hi, I wonder if someone could tell me more about the speed and size of compiled Haskell code. E.g. if one uses GHC to compile Haskell code into native code what speed performance can be expected versus a same program written in C (Hints about the nhc compiler are welcome). Is lazyness as good as strictness. What about Haskell 98 versus (I anticipate) Haskell 2 Thanks Jan Brosius
speed of compiled Haskell code. Reply
Jan Brosius [EMAIL PROTECTED] writes on 16 Mar 2000 on speed and size of compiled Haskell code [..] E.g. if one uses GHC to compile Haskell code into native code what speed performance can be expected versus a same program written in C [..] My experience with the program of generating permutations on [1..10] showed that the code produced by ghc-4.04 is 22 times slower than certain specially written C program. Only the C program algorithm was taken very different from Haskell's one. For each system has its own best algorithm and appropriate data structure. But this example task was chosen as unlucky for Haskell. In other, average case, I expect the ratio of 6-10. But I am not so sure. It is easy to mistake with such comparison. Is lazyness as good as strictness. It helps to write simpler programs, but brings certain average cost overhead. The average practical cost difference does not seem great, and it looks like it is a matter of taste, what to choose. -- Sergey Mechveliani [EMAIL PROTECTED]
Re: speed and size of compiled Haskell code
I wonder if someone could tell me more about the speed and size of compiled Haskell code. E.g. if one uses GHC to compile Haskell code into native code what speed performance can be expected versus a same program written in C (Hints about the nhc compiler are welcome). Without going into the question of comparing Haskell performance with C performance, we can do a rough comparison of speed and space between the code produced by different Haskell compilers. GHC and HBC tend to produce code that is, broadly speaking, equally fast, with nhc98 trailing an order of magnitude behind. GHC builds the largest code, with HBC second, and nhc98 by far the smallest by an order of magnitude again. I haven't got any test figures for HBC, but comparing other Haskell systems for some example programs, executable code sizes are as follows: GHC nhc98 calendars190k 81k infer318k 89k bspt 480k127k nhccomp 8113k861k Sample runtimes are (in seconds): GHC nhc98 Hugs calendars0.1 1.0 7.3 infer1.718.6 35.5 bspt 2.410.9 70.8 prolog 3.540.8112.8 These obviously give just a rough guide. Most of these figures are taken from: "Compiling lazy functional programs for the Java Virtual Machine", David Wakeling, Journal of Functional Programming 9(6), Nov 1999. By the way, I recommend this paper if you want to see how Haskell code compares with hand-written Java code, as well as machine-generated Java code. Interesting stuff. Regards, Malcolm
newtypes
The Haskell report says that in newtype T = C t T uses the same representation as t, and so coercions between the two can be implemented without execution time overhead. Furthermore, the report says that "unlike type synonyms, newtype may be used to define recursive types." How are these two statements reconciled for recursive types such as newtype Foo = F Foo or newtype A = MkA B newtype B = MkB A ? Admittedly, you could never construct a value of these types, but, even so, what do these types mean? Chris
newtypes
Adding to Chris' enquiry: newtype Inftype b = A (b,Inftype) newtype Alist a = B (Either () (a,Alist a)) ...and we can (?) create values for them: infy = A (1,infy) onetwothree = B (Right(1,B(Right(2,B(Right(3,Left ())) Stefan Kahrs
Re: newtypes
At 2:38 pm -0500 16/3/00, Chris Okasaki wrote: The Haskell report says that in newtype T = C t T uses the same representation as t, and so coercions between the two can be implemented without execution time overhead. Furthermore, the report says that "unlike type synonyms, newtype may be used to define recursive types." How are these two statements reconciled for recursive types such as newtype Foo = F Foo or newtype A = MkA B newtype B = MkB A ? Admittedly, you could never construct a value of these types, but, even so, what do these types mean? Co-incidentaly I have just been reading a tutorial paper on co-algebras and co-induction: B. Jacobs and J.J.M.M. Rutten A Tutorial on (Co)Algebras and (Co)Induction. Bulletin of EATCS Vol. 62, 1997, pp. 222--259. http://www.cs.kun.nl/~bart/PAPERS/JR.ps.Z I think that this might help shed some light on what these types mean, if not in a specifically Haskell context. Chris Cheers, Neil School of Mathematical and Computing Sciences Victoria University P. O. Box 600 Wellington Tel +64 4 463 5233 xtn 7094 New Zealand mailto:[EMAIL PROTECTED] Vladimir: That passed the time. Estragon: It would have passed in any case. Vladimir: Yes, but not so rapidly.
Re: speed and size of compiled Haskell code
Thu, 16 Mar 2000 18:00:35 +, Malcolm Wallace [EMAIL PROTECTED] pisze:
GHC and HBC tend to produce code that is, broadly speaking,
equally fast,
I experienced each of these compilers producing code about 3 times
faster than the other for a simple program.
--
__("Marcin Kowalczyk * [EMAIL PROTECTED] http://qrczak.ids.net.pl/
\__/ GCS/M d- s+:-- a22 C+++$ UL++$ P+++ L++$ E-
^^ W++ N+++ o? K? w(---) O? M- V? PS-- PE++ Y? PGP+ t
QRCZAK 5? X- R tv-- b+++ DI D- G+ e h! r--%++ y-
Re: newtypes
Thu, 16 Mar 2000 14:38:30 -0500, Chris Okasaki [EMAIL PROTECTED] pisze:
How are these two statements reconciled for recursive
types such as
newtype Foo = F Foo
IMHO simply the only value of this type is bottom. I see no problem
here, neither does Hugs.
But GHC sees some problem and loops forever trying to compile this :-)
--
__("Marcin Kowalczyk * [EMAIL PROTECTED] http://qrczak.ids.net.pl/
\__/ GCS/M d- s+:-- a22 C+++$ UL++$ P+++ L++$ E-
^^ W++ N+++ o? K? w(---) O? M- V? PS-- PE++ Y? PGP+ t
QRCZAK 5? X- R tv-- b+++ DI D- G+ e h! r--%++ y-
Re: newtypes
Marcin 'Qrczak' Kowalczyk writes: Thu, 16 Mar 2000 14:38:30 -0500, Chris Okasaki [EMAIL PROTECTED] pisze: How are these two statements reconciled for recursive types such as newtype Foo = F Foo IMHO simply the only value of this type is bottom. [...] Hi. Shouldn't applying (\(F _) - ()) differentiate between bottom and (F bottom)? Do the two statements reconcile trivially in this case, into "Foo has the same representation as Foo"? Regards, Tom
Re: newtypes
On 17-Mar-2000, Tom Pledger [EMAIL PROTECTED] wrote: Marcin 'Qrczak' Kowalczyk writes: Thu, 16 Mar 2000 14:38:30 -0500, Chris Okasaki [EMAIL PROTECTED] pisze: How are these two statements reconciled for recursive types such as newtype Foo = F Foo IMHO simply the only value of this type is bottom. [...] Shouldn't applying (\(F _) - ()) differentiate between bottom and (F bottom)? No. See 4.2.3: | Unlike algebraic datatypes, the newtype constructor N is unlifted, | so that N _|_ is the same as _|_. Do the two statements reconcile trivially in this case, into "Foo has the same representation as Foo"? Yes. So the representation of Foo is unspecified. -- Fergus Henderson [EMAIL PROTECTED] | "I have always known that the pursuit WWW: http://www.cs.mu.oz.au/~fjh | of excellence is a lethal habit" PGP: finger [EMAIL PROTECTED]| -- the last words of T. S. Garp.
Re: speed and size of compiled Haskell code
On 16-Mar-2000, Jan Brosius [EMAIL PROTECTED] wrote: I wonder if someone could tell me more about the speed and size of compiled Haskell code. ... What about Haskell 98 versus (I anticipate) Haskell 2 There should be no significant differences as far as performance goes between Haskell 98 and whatever the next revision of Haskell is called. -- Fergus Henderson [EMAIL PROTECTED] | "I have always known that the pursuit WWW: http://www.cs.mu.oz.au/~fjh | of excellence is a lethal habit" PGP: finger [EMAIL PROTECTED]| -- the last words of T. S. Garp.
The return of the Void [Was: newtypes]
On Thu, 16 Mar 2000, Chris Okasaki wrote:
newtype Foo = F Foo
Interesting loop hole you found there! Semantically it should be pretty
clear what this type means, just as the corresponding meaning on the
value level:
bottom = bottom
Foo is simply Void! (formal def. later)
Void has been in Haskell, I can't really remember why it had to go - well
here it is again anyway!
Admittedly, you could never construct a value of these
types, but, even so, what do these types mean?
Sure you can - as all Haskell types it contains bottom (as defined
above) and for example
void = Void void
which is just another way of defining bottom :: Void.
Semantically the meaning is the least fixed point of the identity functor,
that is the minimal CPO containing only _|_.
Hugs and hbc accept it without complaining. (I haven't got nhc installed.)
What is interesting is that ghc loops when trying to compile this
definition! (Ghc folks, consider this a bug report, details below!)
Patrik Jansson
-- Some examples - all run in hugs and hbc
newtype Void = Void Void deriving Show
void :: Void
void = Void void
bottom :: a
bottom = bottom
newtype A = MkA B deriving Show
newtype B = MkB A deriving Show
a = MkA b
b = MkB a
bot_a = bot_b
bot_b = bot_a
newtype Stream a = C (a,Stream a) deriving Show
scons :: a - Stream a - Stream a
scons x xs = C (x,xs)
ones :: Stream Int
ones = scons 1 ones
newtype List a = L (Either () (a,List a)) deriving Show
nil :: List a
nil = L (Left ())
cons :: a - List a - List a
cons x xs = L (Right (x,xs))
toList :: [a] - List a
toList = foldr cons nil
main = print void
===
minimal test case for ghc
cat newtype.hs __END__
newtype Void = Void Void
main = print ()
__END__
And the output from ghc -v newtype.hs: [Unfortunate line breaks by my
mailer]
The Glorious Glasgow Haskell Compilation System, version 4.06
Effective command line: -v
Ineffective C pre-processor:
echo '{-# LINE 1 "newtype.hs" -}' /tmp/ghc779.cpp cat
newtype.hs /tmp/ghc779.cpp
0.00user 0.00system 0:00.01elapsed 0%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (105major+14minor)pagefaults 0swaps
ghc:compile:Output file newtype.o doesn't exist
ghc:compile:Interface file newtype.hi doesn't exist
ghc:recompile:Input file newtype.hs newer than newtype.o
Haskell compiler:
/usr/lib/ghc-4.06/ghc-4.06/hsc /tmp/ghc779.cpp
-fignore-interface-pragmas -fomit-interface-pragmas -fsimplify [
-fmax-simplifier-iterations4 ] -fwarn-overlapping-patterns
-fwarn-missing-methods -fwarn-missing-fields -fwarn-duplicate-exports
-fhi-version=406 -static
"-himap=.%.hi:/usr/lib/ghc-4.06/ghc-4.06/imports/std%.hi" "-himap-sep=:"-v
-hifile=/tmp/ghc779.hi -C=/tmp/ghc779.hc -F=/tmp/ghc779_stb.c
-FH=/tmp/ghc779_stb.h +RTS -H600 -K100
Glasgow Haskell Compiler, version 4.06, for Haskell 98, compiled by GHC
version 4.06
[ Time passes, eventually I press Ctrl-C ]
Command exited with non-zero status 252
89.31user 0.16system 1:30.49elapsed 98%CPU (0avgtext+0avgdata
0maxresident)k
0inputs+0outputs (1330major+1772minor)pagefaults 0swaps
deleting... /tmp/ghc779.cpp /tmp/ghc779.hi /tmp/ghc779.hc
/tmp/ghc779_stb.c /tmp/ghc779_stb.h
rm -f /tmp/ghc779*
