Re: [Haskell-cafe] Array, Vector, Bytestring
Oops. Ben Gamari bgamari.f...@gmail.com писал(а) в своём письме Tue, 04 Jun 2013 04:41:53 +0300: To be perfectly clear, ByteString and Text target much different use-cases and are hardly interchangeable. While ByteString is, as the name suggests, a string of bytes, Text is a string of characters in a Unicode encoding. When you are talking about unstructured binary data, you should most certainly be using ByteString. Why create a special case? Right now you should use ByteString, yes, but I wish I could just use a generic array of Word8. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Array, Vector, Bytestring
Hi Clark, How is this a problem? If you're representing text, use 'text'. If you're representing a string of bytes, use 'bytestring'. If you want an array of values, think c++ and use 'vector'. the problem is that all those packages implement the exact same data type from scratch, instead of re-using an implementation of a general-purpose array internally. That is hardly desirable, nor is it necessary. Take care, Peter ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Array, Vector, Bytestring
On Tue, Jun 04, 2013 at 04:01:37PM +0200, Peter Simons wrote: How is this a problem? If you're representing text, use 'text'. If you're representing a string of bytes, use 'bytestring'. If you want an array of values, think c++ and use 'vector'. the problem is that all those packages implement the exact same data type from scratch, instead of re-using an implementation of a general-purpose array internally. That is hardly desirable, nor is it necessary. Just to clarify for those on the sidelines, the issue is duplication of implementation details, rather than duplication of functionality? Tom ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Array, Vector, Bytestring
Just to clarify for those on the sidelines, the issue is duplication of
implementation details, rather than duplication of functionality?
Well to me, that is not the main issue. The main issue is that you have
to study all of them and depending on which libraries you want to use
have to convert between them, which could be expensive and is definitely
annoying.
I made a few simple benchmarks comparing the three libraries you can
find the code attached.
this is compiled with -O2
# simple sum of 100 Word8 elements
Unboxed Vector 1.114060 ms
Storable Vector 795.1207 us
Primitive Vector 1.116145 ms
ByteString 9.076256 ms
array library has no fold or sum function
# simple sum of 100 more or less randomly chosen elements
Unboxed Vector (unsafe)33.74364 ms
Storable Vector (unsafe) 50.27273 ms
Storable Vector (safe) 67.01634 ms
Primitive Vector (unsafe) 56.29919 ms
ByteString (unsafe)19.29611 ms
ByteString (safe) 18.29065 ms
UArray (safe) 46.88719 ms
unsafe does not exist for array
So Unboxed can be better than Storable but doesn't need to be.
Also, which implementation is faster depends very much on the problem at
hand. And array is just missing half the needed features.
Silvio
import Criterion.Main
import Criterion.Config
import Data.Word
import Data.Bits
import System.Random
import qualified Data.Vector.Unboxed as UVec
import qualified Data.Vector.Storable as SVec
import qualified Data.Vector.Primitive as PVec
import qualified Data.ByteString as BStr
import qualified Data.ByteString.Unsafe as BStr
import qualified Data.Array.Unboxed as UArr
import qualified Data.Array.Storable as SArr
num = 100 :: Int
logNum = floor $ logBase 2 (fromIntegral num)
maskNum = 2^logNum-1
gen = mkStdGen 4653
randomList = take num $ randoms gen
-- PREPARE ARRAYS
uvec = UVec.fromList randomList :: UVec.Vector Word8
svec = SVec.fromList randomList :: SVec.Vector Word8
pvec = PVec.fromList randomList :: PVec.Vector Word8
bstr = BStr.pack randomList :: BStr.ByteString
uarr = UArr.listArray (0,num-1) randomList :: UArr.UArray Int Word8
-- FOR SECOND TEST
randomAccessSum :: (Int - Word8) - Word8
randomAccessSum f = go (num-1) 0 0 where
go 0 _ result = result
go n index oldResult = let result = f index + oldResult in
seq result go (n-1) ((index + 38634329) .. maskNum) result
-- myConfig = defaultConfig { cfgVerbosity = ljust Quiet }
myConfig = defaultConfig
main = do
uvec `seq` svec `seq` pvec `seq` bstr `seq` return ()
defaultMainWith myConfig (return ())
[ bgroup sum
[ bench Unboxed Vector: sum $ whnf UVec.sum uvec
--, bench Unboxed Vector: foldl1' (+) $ whnf (UVec.foldl1' (+)) uvec
, bench Storable Vector: sum $ whnf SVec.sum svec
, bench Storable Vector: foldl1' (+) $ whnf (SVec.foldl1' (+)) svec
--, bench Storable Vector: sum . toList $ whnf (sum . SVec.toList) svec
, bench Primitive Vector: sum $ whnf PVec.sum pvec
, bench ByteString: foldl1' (+) $ whnf (BStr.foldl1' (+)) bstr
, bench ByteString: foldl1 (+) $ whnf (BStr.foldl1 (+)) bstr
]
, bgroup random access sum
[ bench Unboxed Vector: unsafeIndex $ whnf randomAccessSum (UVec.unsafeIndex uvec)
, bench Storable Vector: unsafeIndex $ whnf randomAccessSum (SVec.unsafeIndex svec)
, bench Storable Vector: safe (!) $ whnf randomAccessSum ((SVec.!) svec)
, bench Primitive Vector: unsafeIndex $ whnf randomAccessSum (PVec.unsafeIndex pvec)
, bench ByteString: unsafeIndex $ whnf randomAccessSum (BStr.unsafeIndex bstr)
, bench ByteString: safe index$ whnf randomAccessSum ((BStr.index) bstr)
, bench UArray: safe (!) $ whnf randomAccessSum ((UVec.!) uvec)
]
]
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[Haskell-cafe] Frankfurt Haskell User Group meets 19.6.13, topics: Netwire, Hackathon planning
Dear All, all interested Haskellers are inivted to our Meetup on 19.6.13: http://www.meetup.com/Frankfurt-Haskell-User-Group/events/122879122/. Best regards Peter Althainz ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Array, Vector, Bytestring
I really don't understand this concern. These libraries are tuned for wildly different workloads and use cases, so these sorts of micro benchmarks are an Apples to Frogs comparisons. (even aside from the fact that you'll get very different perf if you used -fllvm and set things up so the array indexing and associated loop code get inlined and fused together!) what is the actual concern? Strawman micro benchmarks that don't even compare the respective libraries for their intended use cases seeems weird. On Tue, Jun 4, 2013 at 12:49 PM, silvio silvio.fris...@gmail.com wrote: Just to clarify for those on the sidelines, the issue is duplication of implementation details, rather than duplication of functionality? Well to me, that is not the main issue. The main issue is that you have to study all of them and depending on which libraries you want to use have to convert between them, which could be expensive and is definitely annoying. I made a few simple benchmarks comparing the three libraries you can find the code attached. this is compiled with -O2 # simple sum of 100 Word8 elements Unboxed Vector 1.114060 ms Storable Vector 795.1207 us Primitive Vector 1.116145 ms ByteString 9.076256 ms array library has no fold or sum function # simple sum of 100 more or less randomly chosen elements Unboxed Vector (unsafe)33.74364 ms Storable Vector (unsafe) 50.27273 ms Storable Vector (safe) 67.01634 ms Primitive Vector (unsafe) 56.29919 ms ByteString (unsafe)19.29611 ms ByteString (safe) 18.29065 ms UArray (safe) 46.88719 ms unsafe does not exist for array So Unboxed can be better than Storable but doesn't need to be. Also, which implementation is faster depends very much on the problem at hand. And array is just missing half the needed features. Silvio ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Array, Vector, Bytestring
On 05/06/13 02:49, silvio wrote: Just to clarify for those on the sidelines, the issue is duplication of implementation details, rather than duplication of functionality? Well to me, that is not the main issue. The main issue is that you have to study all of them and depending on which libraries you want to use have to convert between them, which could be expensive and is definitely annoying. I made a few simple benchmarks comparing the three libraries you can find the code attached. this is compiled with -O2 # simple sum of 100 Word8 elements Unboxed Vector 1.114060 ms Storable Vector 795.1207 us Primitive Vector 1.116145 ms ByteString 9.076256 ms array library has no fold or sum function # simple sum of 100 more or less randomly chosen elements Unboxed Vector (unsafe)33.74364 ms Storable Vector (unsafe) 50.27273 ms Storable Vector (safe) 67.01634 ms Primitive Vector (unsafe) 56.29919 ms ByteString (unsafe)19.29611 ms ByteString (safe) 18.29065 ms UArray (safe) 46.88719 ms unsafe does not exist for array So Unboxed can be better than Storable but doesn't need to be. Also, which implementation is faster depends very much on the problem at hand. And array is just missing half the needed features. Silvio ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe array does provide folding functions, found in its Foldable and Traversable instances. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Array, Vector, Bytestring
array does provide folding functions, found in its Foldable and Traversable instances. Where can I find this? I can neither in the array package nor with google nor with hoogle. Silvio ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Array, Vector, Bytestring
On 05/06/13 07:01, silvio wrote: array does provide folding functions, found in its Foldable and Traversable instances. Where can I find this? I can neither in the array package nor with google nor with hoogle. Silvio ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe Data.Foldable and Data.Traversable, if you hoogle Foldable or Traversable you'll find their modules' docs. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Array, Vector, Bytestring
These libraries are tuned for wildly different workloads and use cases, so these sorts of micro benchmarks are an Apples to Frogs comparisons. You can argue that for any benchmark, but sometimes the choice is between Apples and Frogs. If you have some more extensive benchmarks I'm happy to have a look at them. (even aside from the fact that you'll get very different perf if you used -fllvm and set things up so the array indexing and associated loop code get inlined and fused together!) I think llvm should be default by now. In any case, if you write code, it is important to know how well something works out of box without you having to spend hours optimizing it. what is the actual concern? Strawman micro benchmarks that don't even compare the respective libraries for their intended use cases seeems weird. Perhaps i should have explained that better. If one library was clearly superior to the others, that would have made it easier to choose. Also I wanted to check if Unboxed was usually better than Storable as they are semantically the same (correct me if i'm wrong). Which it is in one example. Still I think Storable could be done so we don't need Unboxed, too. I would have said that sum/fold (i.e. consecutive access of the elements) is a reasonable use case for how we typically use bytestring and the random access sum is a reasonable you use case for how we typically use array/vector. Interestingly enough the performance was exactly opposed to these reasonable use cases. Silvio ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Array, Vector, Bytestring
Hi Tom, On Tue, Jun 04, 2013 at 04:01:37PM +0200, Peter Simons wrote: How is this a problem? If you're representing text, use 'text'. If you're representing a string of bytes, use 'bytestring'. If you want an array of values, think c++ and use 'vector'. the problem is that all those packages implement the exact same data type from scratch, instead of re-using an implementation of a general-purpose array internally. That is hardly desirable, nor is it necessary. Just to clarify for those on the sidelines, the issue is duplication of implementation details, rather than duplication of functionality? I am not sure what the terms duplication of implementation details and duplication of functionality mean in this context. Could you please explain how these two concepts differ in your opinion? Take care, Peter ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Array, Vector, Bytestring
On Tue, Jun 04, 2013 at 11:23:16PM +0200, Peter Simons wrote: On Tue, Jun 04, 2013 at 04:01:37PM +0200, Peter Simons wrote: If you're representing text, use 'text'. If you're representing a string of bytes, use 'bytestring'. If you want an array of values, think c++ and use 'vector'. the problem is that all those packages implement the exact same data type from scratch, instead of re-using an implementation of a general-purpose array internally. That is hardly desirable, nor is it necessary. Just to clarify for those on the sidelines, the issue is duplication of implementation details, rather than duplication of functionality? I am not sure what the terms duplication of implementation details and duplication of functionality mean in this context. Could you please explain how these two concepts differ in your opinion? Hi Peter, When I say duplication of implementation details I believe I mean something like your implementing the exact same data type from scratch. By duplication of functionality, on the other hand, I mean providing two libraries with similar APIs which essentially serve the same purpose. I believe you are suggesting that there is redundancy in the implementation details of these libraries, not in the APIs they expose. Then again, I was just trying to understand the discussion at hand. I don't have an opinion on it. Tom ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Typeable typeclass and type-level naturals
Roman Cheplyaka wrote:
Try adding
deriving instance Typeable 'Zero
deriving instance Typeable a = Typeable ('Succ a)
to your module.
(I haven't tested it — you might need to tweak it a bit.)
Thanks Roman.
Unfortunately, I already tried that (without the constraint Typeable a =,
what a fool), but it did not work. The error is the same with the
constraint:
Derived typeable instance must be of form (Typeable 'Succ)
In the stand-alone deriving instance for
‛Typeable a = Typeable (Succ a)’
What is the problem?
Is it possible that it is a bug in GHC? Indeed, we had unwanted similar
error messages recently:
http://hackage.haskell.org/trac/ghc/ticket/7704
Thanks,
TP
PS: the complete program for a test that shows the error:
--
{-# LANGUAGE GADTs #-}
{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE StandaloneDeriving #-}
import Data.Typeable
data Nat = Zero | Succ Nat
deriving ( Show, Eq, Ord, Typeable )
deriving instance Typeable 'Zero
deriving instance Typeable a = Typeable ('Succ a)
data Box where
Box :: (Typeable s, Show s, Eq s) = s - Box
deriving Typeable
data Proxy a = P deriving Typeable
deriving instance Show Box
instance Eq Box where
(Box s1) == (Box s2) = Just s1 == cast s2
main = do
let one = undefined :: Main.Proxy ('Succ 'Zero)
let foo = Box one
print foo
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[Haskell-cafe] Why isn't hsc2hs functionality provided by ghc?
I was wondering today, why hasn't hsc2hs been merged with ghc so that
it would be possible to add a
{-# LANGUAGE ForeignFunctionInterface #-}
at the top of a source file and then load it with ghci or compile it,
without the intermediate step of calling hsc2hs? This would be exactly
like the CPP extension. I don't have to call cpp manually. All I have
to do is to add {-# LANGUAGE CPP #-} and then ghc will take care of
the rest. This would also mean that there would be no need to have a
separate file extension. Surely I must not be the first person to have
that thought, so there must be a good reason why this hasn't happen
yet, but what is it?
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Re: [Haskell-cafe] How to write a pure String to String function in Haskell FFI to C++
On Sun, Jun 2, 2013 at 10:19 PM, Ting Lei tin...@gmail.com wrote: Thanks for your answers so far. It seems that the laziness of String or [char] is the problem. My question boils then down to this. There are plenty of Haskell FFI examples where simple things like sin/cos in math.h can be imported into Haskell as pure functions. Is there a way to extend that to String without introducing an IO (), but maybe sacrificing laziness? If String has to be lazy, is there another Haskell data type convertible to String that can do the job? The C++/C function (e.g. toUppers) is computation-only and as pure as cos and tan. The fact that marshaling string incurs an IO monad in current examples is kind of unintuitive and like a bug in design. I don't mind making redundant copies under the hood from one type to another.. Hi Ting, In the Foreign.C.String there is a function that converts String to an array (CString = Ptr CChar) which can be handled on the C side: withCString :: String - (CString - IO a) - IO a peekCString :: CString - IO String It's slightly more convenient to use these functions through the preprocessor c2hs, as in the following example http://code.haskell.org/~aavogt/c_toUpper_ffi_ex/. c2hs also has a 'pure' keyword which makes it add the unsafePerformIO, but for whatever reason the side-effects were not done in the right order (the peekCString happened before the foreign function was called). Regards, Adam ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Why isn't hsc2hs functionality provided by ghc?
On 5 June 2013 12:02, silly silly8...@gmail.com wrote:
I was wondering today, why hasn't hsc2hs been merged with ghc so that
it would be possible to add a
{-# LANGUAGE ForeignFunctionInterface #-}
at the top of a source file and then load it with ghci or compile it,
without the intermediate step of calling hsc2hs? This would be exactly
like the CPP extension. I don't have to call cpp manually. All I have
to do is to add {-# LANGUAGE CPP #-} and then ghc will take care of
the rest. This would also mean that there would be no need to have a
separate file extension. Surely I must not be the first person to have
that thought, so there must be a good reason why this hasn't happen
yet, but what is it?
Isn't this done automatically when you have files with the .hsc extension?
--
Ivan Lazar Miljenovic
ivan.miljeno...@gmail.com
http://IvanMiljenovic.wordpress.com
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Re: [Haskell-cafe] Why isn't hsc2hs functionality provided by ghc?
On Tue, Jun 4, 2013 at 10:15 PM, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: Isn't this done automatically when you have files with the .hsc extension? No, it is not. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Why isn't hsc2hs functionality provided by ghc?
On Wed, Jun 5, 2013 at 10:15 AM, Ivan Lazar Miljenovic
ivan.miljeno...@gmail.com wrote:
On 5 June 2013 12:02, silly silly8...@gmail.com wrote:
I was wondering today, why hasn't hsc2hs been merged with ghc so that
it would be possible to add a
{-# LANGUAGE ForeignFunctionInterface #-}
at the top of a source file and then load it with ghci or compile it,
without the intermediate step of calling hsc2hs? This would be exactly
like the CPP extension. I don't have to call cpp manually. All I have
to do is to add {-# LANGUAGE CPP #-} and then ghc will take care of
the rest. This would also mean that there would be no need to have a
separate file extension. Surely I must not be the first person to have
that thought, so there must be a good reason why this hasn't happen
yet, but what is it?
Isn't this done automatically when you have files with the .hsc extension?
cabal handles this transparently, but not ghc. It's frustrating when you
want to develop a project with ghci.
I don't think it's a good idea to merge hsc2hs syntax into Haskell files.
In particular, it's often useful to inspect the intermediate .hs file
produced by hsc2hs during development or debugging. Also it would
complicate ghc's parser, etc...
My preferred solution would be to have ghc/ghci automatically run hsc2hs
(support c2hs also?) when necessary. But so long as it's handled
automatically, I wouldn't be particularly bothered by the implementation.
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Re: [Haskell-cafe] Why isn't hsc2hs functionality provided by ghc?
On Tue, Jun 4, 2013 at 8:45 PM, John Lato jwl...@gmail.com wrote:
On Wed, Jun 5, 2013 at 10:15 AM, Ivan Lazar Miljenovic
ivan.miljeno...@gmail.com wrote:
On 5 June 2013 12:02, silly silly8...@gmail.com wrote:
I was wondering today, why hasn't hsc2hs been merged with ghc so that
it would be possible to add a
{-# LANGUAGE ForeignFunctionInterface #-}
at the top of a source file and then load it with ghci or compile it,
without the intermediate step of calling hsc2hs? This would be exactly
like the CPP extension. I don't have to call cpp manually. All I have
to do is to add {-# LANGUAGE CPP #-} and then ghc will take care of
the rest. This would also mean that there would be no need to have a
separate file extension. Surely I must not be the first person to have
that thought, so there must be a good reason why this hasn't happen
yet, but what is it?
Isn't this done automatically when you have files with the .hsc extension?
cabal handles this transparently, but not ghc. It's frustrating when you
want to develop a project with ghci.
I don't think it's a good idea to merge hsc2hs syntax into Haskell files.
In particular, it's often useful to inspect the intermediate .hs file
produced by hsc2hs during development or debugging. Also it would
complicate ghc's parser, etc...
My preferred solution would be to have ghc/ghci automatically run hsc2hs
(support c2hs also?) when necessary. But so long as it's handled
automatically, I wouldn't be particularly bothered by the implementation.
How about having a `ghci` command for cabal? Or does the automatic
requirement really need to be part of ghc to work the way you want?
(BTW, cabal-dev does have a `ghci` command, but I haven't tested to
see if it does the hsc - hs conversion.)
Jason
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Re: [Haskell-cafe] Int is broken [Was: Different answers on different machines]
On 4/06/2013, at 4:22 PM, Rustom Mody wrote: On Tue, Jun 4, 2013 at 7:35 AM, Richard A. O'Keefe o...@cs.otago.ac.nz wrote: On 3/06/2013, at 6:58 PM, Carter Schonwald wrote: If the Int type had either of these semantics by default, many many performance sensitive libraries would suddenly have substantially less compelling performance. Every single operation that was branchless before would have a branch *every* operation. this would be BAD. Actually, the x86 can be configured to trap integer overflows, so on that not entirely unpopular platform, there need be NO extra branches. Well yes and no. See http://software.intel.com/en-us/forums/topic/306156 I made a mistake, for which I apologise. There were two things I wanted the x86 to trap, several years ago, and I found that one of them *could* be trapped and the other could not. The one that couldn't was integer overflow. I do note that the page cited answers a *different* question which is does the Intel COMPILER support integer overflow trapping. The question I answered wrongly was does the Intel HARDWARE support integer overflow trapping (by raising an exception on integer overflow if a bit is set in a certain control register). Having apologised for my error, I close with the observation that Jacob Navia, developer of lcc-win32 (he started with the LCC compiler but added serious x86-specific optimisation and other Windows goodness), claims that sticking JO after signed integer operations adds very little to run time because it is predicted very well by the branch prediction hardware, since it is almost never taken. In Discipline of Programming (in 1976!) Dijkstra exactly described this problem, and squarely put the blame on poorly engineered machines. He introduced 3 concepts/terms: UM : unbounded machine SLM : sufficiently large machine HSLM : hopefully sufficiently large machine Dijkstra was a Burroughs Research Fellow, and the B6700 was a textbook example of an HSLM. I couldn't believe how primitive other systems were after using that. The signed-integer-overflow-trapping C compiler I mentioned was a MIPS one (MIPS distinguishing between ADD and ADDU, c). ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Why isn't hsc2hs functionality provided by ghc?
cabal-dev ghci does work with hsc2hs, but only because it doesn't interpret
your source. Rather, cabal-dev ghci loads ghci using the sandbox install
of your package, which is less useful for a variety of reasons.
Aside from that detail, I wouldn't gain any benefit from having this
feature built in to ghci instead of accessing ghci via cabal (or
cabal-dev). cabal seems like a better location, and it's aware of several
preprocessors already.
On Wed, Jun 5, 2013 at 12:00 PM, Jason Dagit dag...@gmail.com wrote:
On Tue, Jun 4, 2013 at 8:45 PM, John Lato jwl...@gmail.com wrote:
On Wed, Jun 5, 2013 at 10:15 AM, Ivan Lazar Miljenovic
ivan.miljeno...@gmail.com wrote:
On 5 June 2013 12:02, silly silly8...@gmail.com wrote:
I was wondering today, why hasn't hsc2hs been merged with ghc so that
it would be possible to add a
{-# LANGUAGE ForeignFunctionInterface #-}
at the top of a source file and then load it with ghci or compile it,
without the intermediate step of calling hsc2hs? This would be exactly
like the CPP extension. I don't have to call cpp manually. All I have
to do is to add {-# LANGUAGE CPP #-} and then ghc will take care of
the rest. This would also mean that there would be no need to have a
separate file extension. Surely I must not be the first person to have
that thought, so there must be a good reason why this hasn't happen
yet, but what is it?
Isn't this done automatically when you have files with the .hsc
extension?
cabal handles this transparently, but not ghc. It's frustrating when you
want to develop a project with ghci.
I don't think it's a good idea to merge hsc2hs syntax into Haskell files.
In particular, it's often useful to inspect the intermediate .hs file
produced by hsc2hs during development or debugging. Also it would
complicate ghc's parser, etc...
My preferred solution would be to have ghc/ghci automatically run hsc2hs
(support c2hs also?) when necessary. But so long as it's handled
automatically, I wouldn't be particularly bothered by the implementation.
How about having a `ghci` command for cabal? Or does the automatic
requirement really need to be part of ghc to work the way you want?
(BTW, cabal-dev does have a `ghci` command, but I haven't tested to
see if it does the hsc - hs conversion.)
Jason
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