February 2012 - jhc - Haskell.org

New Extension: foreign C imports that return multiple values
by John Meacham 11 Feb '12

11 Feb '12

I just implemented a new extension for jhc that I thought the community might have feedback on, it allows foreign imports of c routines to automaticall marshall multiple return values using the common fill in the pointer idiom used by the stardard C libraries. This completely removes most of the need for unsafePerformIO and the related Storable dependencies. Notably, many low lever floating point routines use this which really should be inlined and the optimizer can't see through the unsafePerformIO. here are the docs # foreign imports with multiple return values. foreign C imports may return multiple values. To indicate this is the case, use an unboxed tuple as the return value. The first return value will be the value the function directly returns, the rest will be passed as pointers at the end of the functions argument list. Only pure (non IO) functions may return multiple values. ~~~~ -- frexp has C prototype -- double frexp(double x, int *exp); -- so it would normally have an import like so, requiring the IO module and -- Storable to call what is otherwise a pure function. foreign import ccall "math.h frexp" c_frexp :: Double -> Ptr CInt -> IO Double -- This extension allows it to be declared as so foreign import ccall "math.h frexp" c_frexp :: Double -> (# Double, CInt #) -- The second return value is added as the last 'exp' parameter then read out -- of the allocated memory. The contents of the memory passed into the function -- is undefined. ~~~~ John

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type of main
by Daniel Gorín 11 Feb '12

11 Feb '12

Hi I noticed that jhc is not checking what the type of the main function is. In particular, it rejects this module: > main = return () because the inferred type, Monad m => m () is not monomorphic. This may typically happen if the most general type for main is MonadIO m => m (). On the other hand, the following module is accepted: > main :: [()] > main = return () The resulting program does not crash (as I had expected!) but prints [()] instead. In any case, according to the Haskell 98 Report (sec. 5), main has to be "a computation of type IO t, for some type t". I'm attaching a patch that enforces this (I think) by unifying, during the type-checking, the type of the main function with IO t. Daniel

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darcs patch: add extension to allow multiple return v... (and 1 more)
by John Meacham 11 Feb '12

11 Feb '12

Thu Feb 9 06:22:28 PST 2012 John Meacham <john(a)repetae.net> * add extension to allow multiple return values from c functions Thu Feb 9 12:13:51 PST 2012 John Meacham <john(a)repetae.net> * add documentation for the multi-return ccall extension, clean up code.

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darcs patch: add 'capi' foreign function call type, s... (and 3 more)
by John Meacham 11 Feb '12

11 Feb '12

Thu Feb 9 01:16:11 PST 2012 John Meacham <john(a)repetae.net> * add 'capi' foreign function call type, simplify type of E.FromHs monad, check for more FFI related errors Thu Feb 9 02:07:04 PST 2012 John Meacham <john(a)repetae.net> * turn ExtType into a real abstract type Thu Feb 9 02:49:20 PST 2012 John Meacham <john(a)repetae.net> * remove APrim type, use Prim directly, clean up corresponding cruft. Thu Feb 9 03:42:21 PST 2012 John Meacham <john(a)repetae.net> * fix obscure error message for invalid instance reported by roman

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darcs patch: Add some more exotic primitive ops, ffs, ... (and 2 more)
by John Meacham 11 Feb '12

11 Feb '12

Wed Feb 8 23:08:48 PST 2012 John Meacham <john(a)repetae.net> * Add some more exotic primitive ops, ffs,clz,ctz,byteswap,popcount,parity. Thu Feb 9 01:06:47 PST 2012 John Meacham <john(a)repetae.net> * add foreign types, interpret Ptr when creating external C types Thu Feb 9 01:15:27 PST 2012 John Meacham <john(a)repetae.net> * add md5lazyIO, check for bad paths in createTempFile

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fixed tarball
by John Meacham 10 Feb '12

10 Feb '12

I have uploaded an updated tarball that fixes the src/Options.hs issue that some people were having. John

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jhc's development state and an embedded dream
by Jorge Marques Pelizzoni 10 Feb '12

10 Feb '12

Hi, all! I bumped into JHC totally by chance and got quite interested. It's been a while since I started dreaming of developing embedded real-time systems in Haskell subject to somewhat hard memory constraints (from 32KB to 128KB RAM). Am I wrong in guessing that JHC might be the best shot we have so far in that direction? Would it be applicable at all in that scenario? JHC's site mentions that the description of development state in JHC's Original Page is out of date. Could anyone possibly provide/point to a summary of recent developments? Thanks in advance. Cheers, Jorge. 2012/2/10 Daniel Gorín <jcpetruzza(a)gmail.com>: > Hi John, > > In case it helps, I was able to build jhc from the tarball by changing > the line in the Makefile that says > > options.mkd: src/Options.hs | jhc > > to just > > options.mkd: jhc > > Incidentally, the newest version of the pretty package (e.g., the one > that comes with ghc 7.4) defines a Monoid instance for Doc, which > conflicts with the one defined in jhc. I just patched the Makefile to > use an older version of the package, I don't know what the usual method > to deal with this is. > > Thanks, > Daniel > > On Wed, 2012-02-08 at 15:05 -0800, John Meacham wrote: >> Hi, looks like the tarball doesn't include the original files that go >> through drift. it shouldn't need them to compile, strange that it >> needed them for you. >> >> You can grab the source from darcs to work around the issue. I'll put >> up a fixed tarball when I debug the issue. >> >> John >> >> On Wed, Feb 8, 2012 at 4:04 AM, Daniel Gorín <jcpetruzza(a)gmail.com> wrote: >> > Hi >> > >> > I wanted to try jhc 0.8. I followed the instructions here [1], but after >> > unpacking jhc-0.8.0.tar.gz, configure runs ok but make fails with: >> > >> > $ make >> > perl ./utils/op_raw.prl src/RawFiles src/data/ViaGhc.hs >> > src/data/prelude.m4 src/data/targets.ini rts/rts_constants.h >> > rts/stableptr.c rts/queue.h src/data/HsFFI.h rts/wsize.h rts/bitarray.h >> > ChangeLog src/data/shortchange.txt > src/RawFiles.hs >> > make: *** No rule to make target `src/Options.hs', needed by >> > `drift_processed/Options.hs'. Stop. >> > >> > Any ideas? >> > >> > Thanks, >> > Daniel >> > >> > [1] http://repetae.net/computer/jhc/building.shtml >> > >> > >> > >> > _______________________________________________ >> > jhc mailing list >> > jhc(a)haskell.org >> > http://www.haskell.org/mailman/listinfo/jhc > > > > _______________________________________________ > jhc mailing list > jhc(a)haskell.org > http://www.haskell.org/mailman/listinfo/jhc

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couldn't build jhc-0.8 from the tarball
by Daniel Gorín 10 Feb '12

10 Feb '12

Hi I wanted to try jhc 0.8. I followed the instructions here [1], but after unpacking jhc-0.8.0.tar.gz, configure runs ok but make fails with: $ make perl ./utils/op_raw.prl src/RawFiles src/data/ViaGhc.hs src/data/prelude.m4 src/data/targets.ini rts/rts_constants.h rts/stableptr.c rts/queue.h src/data/HsFFI.h rts/wsize.h rts/bitarray.h ChangeLog src/data/shortchange.txt > src/RawFiles.hs make: *** No rule to make target `src/Options.hs', needed by `drift_processed/Options.hs'. Stop. Any ideas? Thanks, Daniel [1] http://repetae.net/computer/jhc/building.shtml

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Re: [jhc] [Haskell] ANNOUNCE: jhc-0.8.0
by John Meacham 09 Feb '12

09 Feb '12

Thanks. I have included your patch. However the ultimate root cause of the Options.hs is not that it isn't being included, it is under drift_processed/Options.hs, the issue is that the Makefile still seems to think it needs the original at least for you for some reason and isn't using the drift_procesed one. hmm.. John On Thu, Feb 9, 2012 at 10:49 AM, Sergei Trofimovich <slyich(a)gmail.com> wrote: > On Tue, 7 Feb 2012 20:03:20 -0800 > John Meacham <john(a)repetae.net> wrote: > >> I am happy to announce jhc 0.8.0 >> >> There have been A lot of major changes in jhc with this release. >> >> - http://repetae.net/computer/jhc > > Hi John! > > Release tarball is missing src/Options.hs file. Sent a patch via 'darcs send'. > > ] hunk ./Makefile.am 30 > - src/Name/Prim.hs src/PackedString.hs src/Ho/ReadSource.hs \ > + src/Name/Prim.hs src/Options.hs src/PackedString.hs src/Ho/ReadSource.hs \ > > -- > > Sergei

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Rank 2 types error
by Roman Cheplyaka 08 Feb '12

08 Feb '12

Hi, The following program is accepted by GHC 7 with -XRank2Types: class C a where f :: a -> a newtype R = R (forall a . C a => a) instance C R where f (R x) = R $ f x main = return () jhc 0.8 gives the following error: [1 of 1] Main (...............jhci: user error ( What: failure Why: Signature too Weak: [] does not imply [Main.C Main.v11] Where: on line 7 in j.hs in the explicitly typed Instance@.iMain.f.Main.R (Main.R Main.6_x) = Main.R Jhc.Basics.$ Main.f Main.6_x {- on line 7 -} Compilation of module: Main) Is this difference in behaviour intended, and how can I make something like that compile? -- Roman I. Cheplyaka :: http://ro-che.info/

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