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Today's Topics:
1. compilation error for jhc (Fabien R)
2. Re: compilation error for jhc (David McBride)
3. Parsing 'A's and then ('A's or 'B's) (Simon Jakobi)
4. Re: Parsing 'A's and then ('A's or 'B's) (Francesco Ariis)
5. Re: Parsing 'A's and then ('A's or 'B's) (Simon Jakobi)
6. Re: Functional Programming for the Object Oriented
(?ystein Kolsrud)
7. Re: Parsing 'A's and then ('A's or 'B's) (Alex Belanger)
----------------------------------------------------------------------
Message: 1
Date: Sun, 24 Jan 2016 13:05:16 +0100
From: Fabien R <theedge...@free.fr>
To: Haskell Beginners <beginners@haskell.org>
Subject: [Haskell-beginners] compilation error for jhc
Message-ID: <56a4bdfc.8070...@free.fr>
Content-Type: text/plain; charset=utf-8; format=flowed
Hello,
I want to build jhc 0.82 on debian/amd64.
I downloaded the sources and successfully configured the build.
The compilation fails with this error:
[149 of 186] Compiling Ho.Binary ( src/Ho/Binary.hs,
src/Ho/Binary.o )
src/Ho/Binary.hs:164:10:
Duplicate instance declarations:
instance [overlap ok] Binary Data.Version.Version
-- Defined at src/Ho/Binary.hs:164:10
instance [safe] Binary Data.Version.Version
-- Defined in `binary-0.8.0.0:Data.Binary.Class'
Makefile:1441: recipe for target 'jhc' failed
The corresponding source code in src/Ho/Binary.hs is:
import Data.Binary
import qualified Data.Version
instance Binary Data.Version.Version where
put (Data.Version.Version a b) = put a >> put b
get = liftM2 Data.Version.Version get get
In the package binary, is this error due to this line ?
import Data.Version (Version(..))
Any hint to solve this ?
--
Fabien
------------------------------
Message: 2
Date: Sun, 24 Jan 2016 08:59:03 -0500
From: David McBride <toa...@gmail.com>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <beginners@haskell.org>
Subject: Re: [Haskell-beginners] compilation error for jhc
Message-ID:
<CAN+Tr40P=edvxzo6mbfiwzxe1fjk8x3s2qtu5_rvxbfxvcw...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
It looks like the binary package got its own instance for the version
datatype. You could probably make it build by just removing that instance
from Binary.hs.
And I don't want to dissuade you, but unless there is a reason for you to
use jhc, just be aware that ghc has pretty much become the defacto haskell
compiler and the others have started to bit rot.
On Sun, Jan 24, 2016 at 7:05 AM, Fabien R <theedge...@free.fr> wrote:
> Hello,
> I want to build jhc 0.82 on debian/amd64.
> I downloaded the sources and successfully configured the build.
> The compilation fails with this error:
>
> [149 of 186] Compiling Ho.Binary ( src/Ho/Binary.hs,
> src/Ho/Binary.o )
>
> src/Ho/Binary.hs:164:10:
> Duplicate instance declarations:
> instance [overlap ok] Binary Data.Version.Version
> -- Defined at src/Ho/Binary.hs:164:10
> instance [safe] Binary Data.Version.Version
> -- Defined in `binary-0.8.0.0:Data.Binary.Class'
> Makefile:1441: recipe for target 'jhc' failed
>
> The corresponding source code in src/Ho/Binary.hs is:
>
> import Data.Binary
> import qualified Data.Version
>
> instance Binary Data.Version.Version where
> put (Data.Version.Version a b) = put a >> put b
> get = liftM2 Data.Version.Version get get
>
> In the package binary, is this error due to this line ?
>
> import Data.Version (Version(..))
>
> Any hint to solve this ?
>
> --
> Fabien
>
> _______________________________________________
> Beginners mailing list
> Beginners@haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
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Message: 3
Date: Sun, 24 Jan 2016 19:11:08 +0100
From: Simon Jakobi <simon.jak...@googlemail.com>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <beginners@haskell.org>
Subject: [Haskell-beginners] Parsing 'A's and then ('A's or 'B's)
Message-ID:
<CAGtp2ShFLsmdAsbHRA1gVfx_vGu6TvWyOyef=1PjYtVTn=0...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hi!
I want to test whether a sequence of the characters 'A' and 'B' can
represent a sequence of the symbols x and y where x may be represented by
one or more 'A's and y may be represented by one or more 'A's or one or
more 'B's.
In code, I would like to see the following:
?> "AABB" `represents` [x, y]
True
?> "AA" `represents` [x, y]
True
But with my current implementation using attoparsec only the first example
works as expected:
import Control.Applicative
import Data.Attoparsec.ByteString.Char8
import Data.ByteString
import Data.Either
import Data.Foldable
import Data.Word
type Symbol = Parser [Word8]
x :: Symbol
x = many1 (char8 'A')
y :: Symbol
y = many1 (char8 'A') <|> many1 (char8 'B')
represents :: ByteString -> [Symbol] -> Bool
bs `represents` symbols =
isRight $ parseOnly ((sequenceA_ symbols) *> endOfInput) bs
It seems that in
"AA" `represents` [x, y]
x consumes all the 'A's, leaving none for y.
Is it possible to solve this with attoparsec or are there other parsing
libraries that I could use instead?
Cheers,
Simon
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Message: 4
Date: Sun, 24 Jan 2016 20:19:42 +0100
From: Francesco Ariis <fa...@ariis.it>
To: beginners@haskell.org
Subject: Re: [Haskell-beginners] Parsing 'A's and then ('A's or 'B's)
Message-ID: <20160124191942.ga1...@casa.casa>
Content-Type: text/plain; charset=utf-8
On Sun, Jan 24, 2016 at 07:11:08PM +0100, Simon Jakobi wrote:
> I want to test whether a sequence of the characters 'A' and 'B' can
> represent a sequence of the symbols x and y where x may be represented by
> one or more 'A's and y may be represented by one or more 'A's or one or
> more 'B's.
>
> In code, I would like to see the following:
>
> ?> "AABB" `represents` [x, y]
> True
> ?> "AA" `represents` [x, y]
> True
Hello Simon,
if I understood your specification correctly, there would be multiple
ways to parse the string "AAA":
- 3 'x' elements ("A", "A", "A")
- 2 'x' elements ("AA", "A")
- 2 'x' elements again (first one shorter) ("A", "AA")
- 1 'x' element ("AAA")
Which of these four should we choose? Maybe "parse as many As as possible
without consuming the A followed by a series of B"? If so, a useful
combinator is `notFollowedBy` (present in parsec, pretty sure is in
attoparsec too, if not it can be easily replicated).
Does that help?
------------------------------
Message: 5
Date: Sun, 24 Jan 2016 22:56:31 +0100
From: Simon Jakobi <simon.jak...@googlemail.com>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <beginners@haskell.org>
Subject: Re: [Haskell-beginners] Parsing 'A's and then ('A's or 'B's)
Message-ID:
<cagtp2shvdbslft-wwk+6tpzrha-g50bvbkfhavvfdau-zcy...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hi Francesco,
Thanks for your response!
> if I understood your specification correctly, there would be multiple
> ways to parse the string "AAA":
>
> - 3 'x' elements ("A", "A", "A")
> - 2 'x' elements ("AA", "A")
> - 2 'x' elements again (first one shorter) ("A", "AA")
> - 1 'x' element ("AAA")
>
There would be even more ways because 'y', too, can represent one or more
'A's.
Which of these four should we choose?Maybe "parse as many As as possible
> without consuming the A followed by a series of B"?
I don't think that there could be a general rule.
For the string "AABB" and the sequence of symbols [x, y, y] there would be
two possible parses:
[x: "AA", y: "B", y: "B"]
or
[x: "A", y: "A", y: "BB"].
I only care whether there are any valid parses.
I've just tried to solve the problem with regular expressions (using
pcre-light) and didn't come across the same problem. Is this due to
attoparsec not being able to "backtrack" (not sure if this is the right
term)? Is backtracking something that parsers generally are incapable of?
Cheers,
Simon
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Message: 6
Date: Sun, 24 Jan 2016 23:35:01 +0100
From: ?ystein Kolsrud <kols...@gmail.com>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <beginners@haskell.org>
Subject: Re: [Haskell-beginners] Functional Programming for the Object
Oriented
Message-ID:
<CAH_oh=wq34gNn+hZ-fid3z-iDoewQLW2rC09gEDaGHGB27=u...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Great! I hope it was useful to you.
Best regards, ?ystein Kolsrud
On Tue, Dec 8, 2015 at 12:45 PM, David Moberg <kaddk...@gmail.com> wrote:
> Thanks I liked this video! :)
>
> 2015-11-18 20:35 GMT+01:00 ?ystein Kolsrud <kols...@gmail.com>:
>>
>> I gave a presentation on functional programming a couple of weeks ago
>> that I thought might be of interest to this community as well:
>>
>> https://www.youtube.com/watch?v=I2tMmsZC1ZU
>>
>> It's target audience is programmers familiar with object oriented
>> programming, and it presents how concepts from the functional paradigm
>> are relevant also in most modern OO languages.
>>
>> For more information about the presentation, please refer to the following
>> site:
>>
>>
>> http://www.foocafe.org/previous_event/functional-programming-for-the-object-oriented
>>
------------------------------
Message: 7
Date: Mon, 25 Jan 2016 01:10:09 -0500
From: Alex Belanger <i.caught....@gmail.com>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <beginners@haskell.org>
Subject: Re: [Haskell-beginners] Parsing 'A's and then ('A's or 'B's)
Message-ID:
<cadsky2xwlkhar7k5jpgfc5ybo+r-qph7xxvij_jurmatzfy...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
If I understood properly,
Have you considered breaking the input into some sort of pattern mask then
validating it?
map (length . group) "AAABB" === [3,2]. Then you can do the same thing
grouping with the target [x, x, y] into [2, 1]. Then you can zip the lists
and ensure the numbers are all smaller than the other respectively. Also,
the lists themselves have the right lengths and order for their elements.
Examples of successful patterns:
[1,1]
AAA,BB
[1, 2]
AAA,B,B
[2,1]
A,AA,BB
AA,A,BB
[2,2]
A,AA,B,B
AA,A,B,B
Try with other examples I think this would work.
On Jan 24, 2016 4:57 PM, "Simon Jakobi" <simon.jak...@googlemail.com> wrote:
> Hi Francesco,
>
> Thanks for your response!
>
>
>> if I understood your specification correctly, there would be multiple
>> ways to parse the string "AAA":
>>
>> - 3 'x' elements ("A", "A", "A")
>> - 2 'x' elements ("AA", "A")
>> - 2 'x' elements again (first one shorter) ("A", "AA")
>> - 1 'x' element ("AAA")
>>
>
> There would be even more ways because 'y', too, can represent one or more
> 'A's.
>
> Which of these four should we choose?Maybe "parse as many As as possible
>> without consuming the A followed by a series of B"?
>
>
> I don't think that there could be a general rule.
>
> For the string "AABB" and the sequence of symbols [x, y, y] there would be
> two possible parses:
>
> [x: "AA", y: "B", y: "B"]
> or
> [x: "A", y: "A", y: "BB"].
>
> I only care whether there are any valid parses.
>
> I've just tried to solve the problem with regular expressions (using
> pcre-light) and didn't come across the same problem. Is this due to
> attoparsec not being able to "backtrack" (not sure if this is the right
> term)? Is backtracking something that parsers generally are incapable of?
>
> Cheers,
> Simon
>
> _______________________________________________
> Beginners mailing list
> Beginners@haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
>
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