July 2004 - Glasgow-haskell-users

RE: type synonyms in instances...
by Simon Peyton-Jones 16 Jul '04

16 Jul '04

It seems that GHC does this by default (which is technically wrong, perhaps). I've just tried it. Simon | -----Original Message----- | From: glasgow-haskell-users-bounces(a)haskell.org [mailto:glasgow-haskell-users- | bounces(a)haskell.org] On Behalf Of MR K P SCHUPKE | Sent: 07 July 2004 11:34 | To: glasgow-haskell-users(a)haskell.org | Subject: type synonyms in instances... | | | Is there any chance of enabling type synonyms in instance declarations. | I remember a posting where is was stated that there was no technical | reason for not being able to do this. | | Could we perhaps have a command line switch to enable this... | | For example, I think the following:- | | instance (HList e HNil) where ... | | is more readable as: | | type HSingleton e = HCons e HNil | | instance (HSingleton e) where ... | | Keean. | _______________________________________________ | Glasgow-haskell-users mailing list | Glasgow-haskell-users(a)haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-haskell-users

1 0

RE: Using GHC and FFI
by Bayley, Alistair 16 Jul '04

16 Jul '04

> After that I wrote ghc -fffi -c test.lhs. But when I call > blah from ghci I get the error message: "test.o unknown symbol '_test' > > I think ghc doen't link test.o to projekt.obj. What do I have to do? I don't know about linking object files I've created myself, but to link an existing library (a .dll on my Windows system) I use these options: -L/path/to/library/file -lprojekt -I/path/to/header/include/directory/if/it/exists If the object file is in the same dir as test.lhs then you might get away with just the -l option. Also, you might have to rename projekt.obj to projekt.o (I don't know if this matters or not). See GHC Users Guide "4.10.7. Options affecting linking", for -L and -l: http://www.haskell.org/ghc/docs/latest/html/users_guide/options-phases.html# OPTIONS-LINKER And see "4.10.3 Options affecting the C pre-processor", for -I: http://www.haskell.org/ghc/docs/latest/html/users_guide/options-phases.html# C-PRE-PROCESSOR I believe you only need to use -I if you're compiling via-c (which happens if you use -O). ----------------------------------------- ***************************************************************** Confidentiality Note: The information contained in this message, and any attachments, may contain confidential and/or privileged material. It is intended solely for the person(s) or entity to which it is addressed. Any review, retransmission, dissemination, or taking of any action in reliance upon this information by persons or entities other than the intended recipient(s) is prohibited. If you received this in error, please contact the sender and delete the material from any computer. *****************************************************************

1 0

RE: effective partial evaluator yet?
by Simon Peyton-Jones 15 Jul '04

15 Jul '04

| My current prototype uses GHC and Template Haskell. It can only | specialise functions that manipulate first order values. It does work | for a number of simple examples eg Ackerman function (specialised on | first argument), matrix multiplication (specialising on fixed size | matrices), a simple language interpreter (specialised to a fixed input | program). You're doing PE of full Haskell, right? Another possibility would be to do PE of Core. It's a much, much, much, much smaller language. Why would you want to do it at the Haskell source level? (Apart from the fact that's what TH directly supports?) Admittedly, if you want annotations, then getting them through to Core un-harmed would require a little work. Simon

2 1

effective partial evaluator yet?
by John Sharley 15 Jul '04

15 Jul '04

Noting Hudak's remark in the conclusion of "Modular Domain Specific Languages and Tools" http://www.cs.chalmers.se/Cs/Grundutb/Kurser/afp/Papers/dsel-hudak.ps that Haskell lacked an effective partial evaluator, and remarks prior to but on the same page as the conclusion that such a thing is very important for DSELs, is there an effective partial evaluator for Haskell yet? If not, what are the prospects (both theoretical and practical) for having an effective partial evaluator for Haskell and GHC in particular?

2 2

RE: "Stricts _"
by Simon Peyton-Jones 14 Jul '04

14 Jul '04

yes it's not meant to come out. It's an internal record of what strictness marks you put on the data type. | -----Original Message----- | From: glasgow-haskell-users-bounces(a)haskell.org [mailto:glasgow-haskell-users- | bounces(a)haskell.org] On Behalf Of Peter Simons | Sent: 13 July 2004 15:02 | To: glasgow-haskell-users(a)haskell.org | Subject: "Stricts _" | | ghci-6.3 (from CVS) shows me strictness information when I | request :info for a data type, like: | | [...] Send Mailbox Stricts: _ [...] | | I have no idea how to read that output, and it doesn't seem | to be documented in the manual either. Does the underscore | signify that (in the example above) Mailbox is a strict | value? Or is it the opposite? | | Sorry if this is a dumb question, but I simply don't know | it. :-) | | Peter | | _______________________________________________ | Glasgow-haskell-users mailing list | Glasgow-haskell-users(a)haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-haskell-users

1 0

RE: "Stricts _"
by Simon Marlow 13 Jul '04

13 Jul '04

On 13 July 2004 15:02, Peter Simons wrote: > ghci-6.3 (from CVS) shows me strictness information when I > request :info for a data type, like: > > [...] Send Mailbox Stricts: _ [...] > > I have no idea how to read that output, and it doesn't seem > to be documented in the manual either. Does the underscore > signify that (in the example above) Mailbox is a strict > value? Or is it the opposite? > > Sorry if this is a dumb question, but I simply don't know > it. :-) I don't think :info is working properly in the HEAD right now. It's something we need to fix before 6.4. I suggest just ignoring the spurious output for now. Cheers, Simon

2 1

"Stricts _"
by Peter Simons 13 Jul '04

13 Jul '04

ghci-6.3 (from CVS) shows me strictness information when I request :info for a data type, like: [...] Send Mailbox Stricts: _ [...] I have no idea how to read that output, and it doesn't seem to be documented in the manual either. Does the underscore signify that (in the example above) Mailbox is a strict value? Or is it the opposite? Sorry if this is a dumb question, but I simply don't know it. :-) Peter

1 0

Error invoking compiler
by Andrei Formiga 10 Jul '04

10 Jul '04

Hi, I'm working with the Haskell plugin for eclipse, but when building a project the compiler outputs the following error: ghc-6.2.1: can't apply -o to multiple source files Usage: For basic information, try the `--help' option. and this is the command line (or should be): ghc --make -odir /home/ktulu/eclipse/runtime-workspace/Hello/out -hidir /home/ktulu/eclipse/runtime-workspace/Hello/out -o /home/ktulu/eclipse/runtime-workspace/Hello/bin/theResult Main.hs funny enough, when using the same command line at a terminal, it compiles ok. Does someone have any thought or ideas on why this is happening ? I'm running GHC 6.2.1 on linux (Fedora Core 2, glibc 2.3), installed from RPM. The same problem was reported on other linux versions and on Mac OS X. It worked fine on previous versions. Thanks in advance for any help. -- []s, Andrei de A. Formiga

1 1

type synonyms in instances...
by MR K P SCHUPKE 07 Jul '04

07 Jul '04

Is there any chance of enabling type synonyms in instance declarations. I remember a posting where is was stated that there was no technical reason for not being able to do this. Could we perhaps have a command line switch to enable this... For example, I think the following:- instance (HList e HNil) where ... is more readable as: type HSingleton e = HCons e HNil instance (HSingleton e) where ... Keean.

1 0

debian package of 6.2.1 has no ghc-pkg-$VERSION
by Johannes Waldmann 06 Jul '04

06 Jul '04

I'm not sure whose fault it is but when building HaXml-1.12, the command ghc-pkg-$VERSION is called which is not provided by the 6.2.1 debian package (from syntaxpolice.org) (of course a symlink from ghc-pkg solves this.) -- -- Johannes Waldmann, Tel/Fax: (0341) 3076 6479 / 6480 -- ------ http://www.imn.htwk-leipzig.de/~waldmann/ ---------

1 0