Re: [Haskell-cafe] question about indentation conventions

[Tom Ellis]

On Mon, Jul 01, 2013 at 05:18:39PM +1200, Richard A. O'Keefe wrote:
> On 1/07/2013, at 1:04 PM, Richard Cobbe wrote:
> > I should have been clearer in my original question: I'm curious about what
> > to do when a multi-argument function application gets split across lines.
> > That wiki page dicsusses how the layout rule interacts with various special
> > forms (let, where, if, do, case), but it doesn't seem to address function
> > applications, beyond implying that it's ok to indent the continuing lines
> > of a function application.
> 
> It looked pretty explicit to me:
> 
>   The golden rule of indentation
>   ...
>   you will do fairly well if you just remember a single rule:
>   Code which is part of some expression should be indented 
>   further in than the beginning of that expression (even if
>   the expression is not the leftmost element of the line).
> 
> This means for example that
>   f (g x
>   y
>   z)
> is OK but
>   f (g x
>   y z)
> is not.

It seems to me that this means

f x1 x2
x3 x4

is not.  The OP was initially asking about this situation.

Tom


___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] question automatic indentation (and so on)

[Joachim Breitner]

Hi,

on a related note: At HaL8 I was wondering how well Haskell would be
suited for a workflow similar to what the go programmers do: Do not
worry about code layout, but let the computer handle it! For more
rationale and examples see
http://golang.org/doc/effective_go.html#formatting

While everyone has his own style and preferences, as soon as multiple
programmers work on the same code, a consistently enforced formatting
would probably help here a lot. Also, I would be happy to give up some
bikeshedding^Wformatting freedom for not having to worry about this
aspect.

I found https://github.com/jaspervdj/stylish-haskell/ (found via
http://stackoverflow.com/q/6870148/946226) which formats just some very
few aspects of Haskell. Does anyone have a more complete solution? Or is
interested in creating one?

Greetings,
Joachim

-- 
Joachim Breitner
  e-Mail: m...@joachim-breitner.de
  Homepage: http://www.joachim-breitner.de
  ICQ#: 74513189
  Jabber-ID: nome...@joachim-breitner.de


signature.asc
Description: This is a digitally signed message part
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

[Haskell-cafe] Installing Z3 on OS X 10.8.4 ( Off topic )

[mukesh tiwari]

Hello all,
Not directly related to Haskell but I am trying to install Z3 to use SBV
package[1]. I followed the instructions[2]  to  install it.

*Mukeshs-MacBook-Pro:SMT mukeshtiwari$ git clone
https://git01.codeplex.com/z3 -b unstable
Cloning into 'z3'...
remote: Counting objects: 16070, done.
remote: Compressing objects: 100% (3928/3928), done.
remote: Total 16070 (delta 12057), reused 16070 (delta 12057)
Receiving objects: 100% (16070/16070), 7.62 MiB | 287 KiB/s, done.
Resolving deltas: 100% (12057/12057), done.*

After installing Z3
*Running python example.py in z3/examples/python gives this result.
*
*Mukeshs-MacBook-Pro:python mukeshtiwari$ python example.py
sat
[y = 4, x = 2]*

but when I am running sbv package, I am getting this error.

*Mukeshs-MacBook-Pro:site-packages mukeshtiwari$ ghci -XScopedTypeVariables
GHCi, version 7.6.1: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Prelude> :m Data.SBV.Bridge.Z3
Prelude Data.SBV.Bridge.Z3> prove $ \(x::SWord8) -> x `shiftL` 2 .== 4*x
Loading package pretty-1.1.1.0 ... linking ... done.
Loading package array-0.4.0.1 ... linking ... done.
Loading package deepseq-1.3.0.1 ... linking ... done.
Loading package filepath-1.3.0.1 ... linking ... done.
Loading package old-locale-1.0.0.5 ... linking ... done.
Loading package time-1.4.0.1 ... linking ... done.
Loading package bytestring-0.10.0.0 ... linking ... done.
Loading package unix-2.6.0.0 ... linking ... done.
Loading package directory-1.2.0.0 ... linking ... done.
Loading package process-1.1.0.2 ... linking ... done.
Loading package old-time-1.1.0.1 ... linking ... done.
Loading package containers-0.5.0.0 ... linking ... done.
Loading package random-1.0.1.1 ... linking ... done.
Loading package template-haskell ... linking ... done.
Loading package QuickCheck-2.5.1.1 ... linking ... done.
Loading package transformers-0.3.0.0 ... linking ... done.
Loading package mtl-2.1.2 ... linking ... done.
Loading package syb-0.3.7 ... linking ... done.
Loading package sbv-2.10 ... linking ... done.
*** An error occurred.
***  Unable to locate executable for z3
***  Executable specified: "z3"
Prelude Data.SBV.Bridge.Z3> *

I have posted every details on installation on pastebin[3]. The
documentation file says that[4] it will install

*2) Building Z3 using make/g++ and Python
Execute:

  autconf
  ./configure
  python scripts/mk_make.py
  cd build
  make
  sudo make install

It will install z3 executable at /usr/bin, libraries at /usr/lib, and
include files at /usr/include.*

Mukeshs-MacBook-Pro:z3 mukeshtiwari$ echo $PATH
/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Users/mukeshtiwari/Programming/GHC/ghc-7.6.1/bin:/Users/mukeshtiwari/.cabal/bin:/Users/mukeshtiwari/Erlang/bin:/Users/mukeshtiwari/Programming/Scala/scala-2.10.0/bin:/usr/local/smlnj-110.75/bin:/Users/mukeshtiwari/.rvm/bin

Could some one please tell me how to solve this problem.

Regards,
Mukesh Tiwari


[1] http://hackage.haskell.org/package/sbv
[2]
http://z3.codeplex.com/wikipage?title=Building%20the%20unstable%20%28working-in-progress%29%20branch&referringTitle=Documentation
[3] http://pastebin.com/K5rq3jCF
[4] http://z3.codeplex.com/SourceControl/latest#README
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Installing Z3 on OS X 10.8.4 ( Off topic )

[mukesh tiwari]

I also tried installing Yices[1]  but still getting same error. I followed
the instructions but still the same error. Seems like I am missing some
crucial details about path but not able to resolve it.

Mukeshs-MacBook-Pro:SMT mukeshtiwari$ cd yices-2.1.0/
Mukeshs-MacBook-Pro:yices-2.1.0 mukeshtiwari$ ls
LICENSENOTICESREADMEbindocetc
examplesincludelib
Mukeshs-MacBook-Pro:yices-2.1.0 mukeshtiwari$ ls
LICENSENOTICESREADMEbindocetc
examplesincludelib
Mukeshs-MacBook-Pro:yices-2.1.0 mukeshtiwari$ cat README
Yices SMT Solver, Copyright SRI International, 2012
===

This file is part of the Yices 2.0 binary distribution for MacOS X.
Yices is distributed free-of-charge for personal use under the terms
of the Yices license (see LICENSE).


Content
---

This distribution includes three solvers

  bin/yices   (for the Yices 2 language)
  bin/yices-smt   (for SMT-LIB 1.2)
  bin/yices-sat   (sat solver, DIMACS format)

and the Yices libraries and header files

  lib/libyices.2.0.0.dylib
  include/yices.h
  include/yices_types.h
  include/yices_limits.h
  include/yices_exit_codes.h


Examples and documentation are in the examples and doc directories.


The binaries and library were linked statically against GMP version 5.0.4,
copyright Free Software Foundation (see NOTICES).



Recommended Library Installation on MacOS X
---

The library's install name is '/usr/local/lib/libyices.2.dylib' so
the following procedure should be used to install it.

1) copy libyices.2.0.0.dylib in /usr/local/lib (this requires
   administrative privileges):

sudo  cp libyices.2.0.0.dylib /usr/local/lib
sudo  chmod 755 /usr/local/lib/libyices.2.0.0.dylib


2) add two symbolic links:

sudo  ln -sf libyices.2.0.0.dylib /usr/local/lib/libyices.dylib
sudo  ln -sf libyices.2.0.0.dylib /usr/local/lib/libyices.2.dylib




For more information, please visit http://yices.csl.sri.com.
Mukeshs-MacBook-Pro:yices-2.1.0 mukeshtiwari$ cd lib/
Mukeshs-MacBook-Pro:lib mukeshtiwari$ ls
libyices.2.1.0.dylib
Mukeshs-MacBook-Pro:lib mukeshtiwari$ sudo  cp libyices.2.1.0.dylib
/usr/local/lib
Password:
Mukeshs-MacBook-Pro:lib mukeshtiwari$ sudo  chmod 755
/usr/local/lib/libyices.2.1.0.dylib
Mukeshs-MacBook-Pro:lib mukeshtiwari$ sudo  ln -sf libyices.2.1.0.dylib
/usr/local/lib/libyices.dylib
Mukeshs-MacBook-Pro:lib mukeshtiwari$ sudo  ln -sf libyices.2.1.0.dylib
/usr/local/lib/libyices.2.dylib

Mukeshs-MacBook-Pro:~ mukeshtiwari$ ghci -XScopedTypeVariables
GHCi, version 7.6.1: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Prelude> :m Data.SBV.Bridge.Yices
Prelude Data.SBV.Bridge.Yices> prove $ \(x::SWord8) -> x `shiftL` 2 .== 4*x
Loading package pretty-1.1.1.0 ... linking ... done.
Loading package array-0.4.0.1 ... linking ... done.
Loading package deepseq-1.3.0.1 ... linking ... done.
Loading package filepath-1.3.0.1 ... linking ... done.
Loading package old-locale-1.0.0.5 ... linking ... done.
Loading package time-1.4.0.1 ... linking ... done.
Loading package bytestring-0.10.0.0 ... linking ... done.
Loading package unix-2.6.0.0 ... linking ... done.
Loading package directory-1.2.0.0 ... linking ... done.
Loading package process-1.1.0.2 ... linking ... done.
Loading package old-time-1.1.0.1 ... linking ... done.
Loading package containers-0.5.0.0 ... linking ... done.
Loading package random-1.0.1.1 ... linking ... done.
Loading package template-haskell ... linking ... done.
Loading package QuickCheck-2.5.1.1 ... linking ... done.
Loading package transformers-0.3.0.0 ... linking ... done.
Loading package mtl-2.1.2 ... linking ... done.
Loading package syb-0.3.7 ... linking ... done.
Loading package sbv-2.10 ... linking ... done.
*** An error occurred.
***  Unable to locate executable for Yices
***  Executable specified: "yices-smt"


Regards,
Mukesh Tiwari

[1] http://yices.csl.sri.com/download-yices2.shtml


On Mon, Jul 1, 2013 at 2:57 PM, mukesh tiwari
wrote:

> Hello all,
> Not directly related to Haskell but I am trying to install Z3 to use SBV
> package[1]. I followed the instructions[2]  to  install it.
>
> *Mukeshs-MacBook-Pro:SMT mukeshtiwari$ git clone
> https://git01.codeplex.com/z3 -b unstable
> Cloning into 'z3'...
> remote: Counting objects: 16070, done.
> remote: Compressing objects: 100% (3928/3928), done.
> remote: Total 16070 (delta 12057), reused 16070 (delta 12057)
> Receiving objects: 100% (16070/16070), 7.62 MiB | 287 KiB/s, done.
> Resolving deltas: 100% (12057/12057), done.*
>
> After installing Z3
> *Running python example.py in z3/examples/python gives this result.
> *
> *Mukeshs-MacBook-Pro:python mukeshtiwari$ python example.py
> sat
> [y = 4, x = 2]*
>
> but when I am running sbv pac

Re: [Haskell-cafe] Installing Z3 on OS X 10.8.4 ( Off topic )

[mukesh tiwari]

Finally I got the Yices working by adding yices-2.1.0/bin to my path. Still
looking to resolve Z3.

Regards,
Mukesh Tiwari


On Mon, Jul 1, 2013 at 3:42 PM, mukesh tiwari
wrote:

> I also tried installing Yices[1]  but still getting same error. I followed
> the instructions but still the same error. Seems like I am missing some
> crucial details about path but not able to resolve it.
>
> Mukeshs-MacBook-Pro:SMT mukeshtiwari$ cd yices-2.1.0/
> Mukeshs-MacBook-Pro:yices-2.1.0 mukeshtiwari$ ls
> LICENSENOTICESREADMEbindocetc
> examplesincludelib
> Mukeshs-MacBook-Pro:yices-2.1.0 mukeshtiwari$ ls
> LICENSENOTICESREADMEbindocetc
> examplesincludelib
> Mukeshs-MacBook-Pro:yices-2.1.0 mukeshtiwari$ cat README
> Yices SMT Solver, Copyright SRI International, 2012
> ===
>
> This file is part of the Yices 2.0 binary distribution for MacOS X.
> Yices is distributed free-of-charge for personal use under the terms
> of the Yices license (see LICENSE).
>
>
> Content
> ---
>
> This distribution includes three solvers
>
>   bin/yices   (for the Yices 2 language)
>   bin/yices-smt   (for SMT-LIB 1.2)
>   bin/yices-sat   (sat solver, DIMACS format)
>
> and the Yices libraries and header files
>
>   lib/libyices.2.0.0.dylib
>   include/yices.h
>   include/yices_types.h
>   include/yices_limits.h
>   include/yices_exit_codes.h
>
>
> Examples and documentation are in the examples and doc directories.
>
>
> The binaries and library were linked statically against GMP version 5.0.4,
> copyright Free Software Foundation (see NOTICES).
>
>
>
> Recommended Library Installation on MacOS X
> ---
>
> The library's install name is '/usr/local/lib/libyices.2.dylib' so
> the following procedure should be used to install it.
>
> 1) copy libyices.2.0.0.dylib in /usr/local/lib (this requires
>administrative privileges):
>
> sudo  cp libyices.2.0.0.dylib /usr/local/lib
> sudo  chmod 755 /usr/local/lib/libyices.2.0.0.dylib
>
>
> 2) add two symbolic links:
>
> sudo  ln -sf libyices.2.0.0.dylib /usr/local/lib/libyices.dylib
> sudo  ln -sf libyices.2.0.0.dylib /usr/local/lib/libyices.2.dylib
>
>
>
>
> For more information, please visit http://yices.csl.sri.com.
> Mukeshs-MacBook-Pro:yices-2.1.0 mukeshtiwari$ cd lib/
> Mukeshs-MacBook-Pro:lib mukeshtiwari$ ls
> libyices.2.1.0.dylib
> Mukeshs-MacBook-Pro:lib mukeshtiwari$ sudo  cp libyices.2.1.0.dylib
> /usr/local/lib
> Password:
> Mukeshs-MacBook-Pro:lib mukeshtiwari$ sudo  chmod 755
> /usr/local/lib/libyices.2.1.0.dylib
> Mukeshs-MacBook-Pro:lib mukeshtiwari$ sudo  ln -sf libyices.2.1.0.dylib
> /usr/local/lib/libyices.dylib
> Mukeshs-MacBook-Pro:lib mukeshtiwari$ sudo  ln -sf libyices.2.1.0.dylib
> /usr/local/lib/libyices.2.dylib
>
> Mukeshs-MacBook-Pro:~ mukeshtiwari$ ghci -XScopedTypeVariables
>
> GHCi, version 7.6.1: http://www.haskell.org/ghc/  :? for help
> Loading package ghc-prim ... linking ... done.
> Loading package integer-gmp ... linking ... done.
> Loading package base ... linking ... done.
> Prelude> :m Data.SBV.Bridge.Yices
> Prelude Data.SBV.Bridge.Yices> prove $ \(x::SWord8) -> x `shiftL` 2 .== 4*x
>
> Loading package pretty-1.1.1.0 ... linking ... done.
> Loading package array-0.4.0.1 ... linking ... done.
> Loading package deepseq-1.3.0.1 ... linking ... done.
> Loading package filepath-1.3.0.1 ... linking ... done.
> Loading package old-locale-1.0.0.5 ... linking ... done.
> Loading package time-1.4.0.1 ... linking ... done.
> Loading package bytestring-0.10.0.0 ... linking ... done.
> Loading package unix-2.6.0.0 ... linking ... done.
> Loading package directory-1.2.0.0 ... linking ... done.
> Loading package process-1.1.0.2 ... linking ... done.
> Loading package old-time-1.1.0.1 ... linking ... done.
> Loading package containers-0.5.0.0 ... linking ... done.
> Loading package random-1.0.1.1 ... linking ... done.
> Loading package template-haskell ... linking ... done.
> Loading package QuickCheck-2.5.1.1 ... linking ... done.
> Loading package transformers-0.3.0.0 ... linking ... done.
> Loading package mtl-2.1.2 ... linking ... done.
> Loading package syb-0.3.7 ... linking ... done.
> Loading package sbv-2.10 ... linking ... done.
> *** An error occurred.
> ***  Unable to locate executable for Yices
> ***  Executable specified: "yices-smt"
>
>
> Regards,
> Mukesh Tiwari
>
> [1] http://yices.csl.sri.com/download-yices2.shtml
>
>
> On Mon, Jul 1, 2013 at 2:57 PM, mukesh tiwari <
> mukeshtiwari.ii...@gmail.com> wrote:
>
>> Hello all,
>> Not directly related to Haskell but I am trying to install Z3 to use SBV
>> package[1]. I followed the instructions[2]  to  install it.
>>
>> *Mukeshs-MacBook-Pro:SMT mukeshtiwari$ git clone
>> https://git01.codeplex.com/z3 -b unstable
>> Cloning into 'z3'...
>> remote: Counting objects: 16070, done.
>> remote: Compress

Re: [Haskell-cafe] question about indentation conventions

[Johannes Waldmann]

>   Code which is part of some expression should be indented 
>   further in than the beginning of that expression [...]

Yes. Then the next question is "how much further in".

My answer is: it does not matter, but make it consistent (like 4 spaces),
with the implication that indentation should *not* depend
on length of identifiers in the previous line(s)

Example (bad):

foo x = do bar
   baz

Example (good):

foo x = do
bar
baz

Reason: when refactoring later changes the name "foo",
or the number or names of its arguments,
you'll have to re-indent code (in the "bad" version):
(a) this needs tool support and
(b) it creates noise in the diffs.

- J.W.



___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] question automatic indentation (and so on)

[Richard Cobbe]

On Mon, Jul 01, 2013 at 09:48:42AM +0200, Joachim Breitner wrote:



> I found https://github.com/jaspervdj/stylish-haskell/ (found via
> http://stackoverflow.com/q/6870148/946226) which formats just some very
> few aspects of Haskell. Does anyone have a more complete solution? Or is
> interested in creating one?

I'd love a fully-automatic indentation tool; it's one of the things about
the Lisp world that I miss.  But is this actually a solvable problem?  I
think that, to be fully correct, an indentation algorithm for Haskell would
have to know not only the syntactic structure of the program but also the
programmer's intent, in some cases.

Heh -- forgive the pun.  Nested CASE expressions are actually one of the
trickiest bits.  If the programmer doesn't put parens around the inner
expression (and doesn't use braces and semis), then only indentation serves
to indicate when the inner case ends and the next branch of the outer case
begins:

case x of
A -> ...
B ->
case y of
Just z -> ...
Nothing -> ...
C -> ...

Similarly (tying this back to my original question), in a do block,
applications that span multiple lines are tricky:

do f x y z
   a b c

How does the indentation tool know if (a b c) is supposed to be the next
item in the do block, or merely a continuation of the previous application
of f?

Richard

___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] question about indentation conventions

[Richard Cobbe]

On Mon, Jul 01, 2013 at 05:18:39PM +1200, Richard A. O'Keefe wrote:
>
> It looked pretty explicit to me:
>
>   The golden rule of indentation
>   ...
>   you will do fairly well if you just remember a single rule:
>   Code which is part of some expression should be indented
>   further in than the beginning of that expression (even if
>   the expression is not the leftmost element of the line).
>
> This means for example that
>   f (g x
>   y
>   z)
> is OK but
>   f (g x
>   y z)
> is not.
>

Sure.  So my first question boils down to which of the two alternatives
below does the community prefer?  (To be clear about the intended
semantics: this is the application of the function f to the arguments x, y,
and z.)

f x
y
z

or

f x
 y
 z

Both are correct, in most contexts.

And then there's the second question: if the second alternative is
preferable, is there a way to get haskell-mode to do it automatically?  As
it is, it refuses to indent y any farther to the right than in the first
alternative.  I can space it in by hand, and then haskell-mode puts z under
y, but that's annoying, and it gets in the way of reindenting large regions
of code automatically.

Richard

___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Installing Z3 on OS X 10.8.4 ( Off topic )

[Johannes Waldmann]

> Unable to locate executable for z3

well, do you really have z3 in the $PATH?  
what does 'which z3' answer?

I used this for installation of z3:
python scripts/mk_make.py --prefix=/usr/local

and note that the install script says:

Z3 shared libraries were installed at /usr/local/lib, make sure this
directory is in your LD_LIBRARY_PATH environment variable.

- J.W.



___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] question automatic indentation (and so on)

[Joachim Breitner]

Hi,

Am Montag, den 01.07.2013, 07:59 -0400 schrieb Richard Cobbe:
> How does the indentation tool know if (a b c) is supposed to be the next
> item in the do block, or merely a continuation of the previous application
> of f?

I would still expect the developer to write correctly intended Haskell,
so the the tool would have to employ a Haskell parser to get an AST
(with extra information on where comments were – probably the trickiest
part) and then pretty-prints it.

If it were not for comments, using haskell-src-exts would already
provide a first approximation to the problem, as shown in this script:
https://github.com/djv/small/blob/master/tidy.hs


Greetings,
Joachim

-- 
Joachim “nomeata” Breitner
  m...@joachim-breitner.de • http://www.joachim-breitner.de/
  Jabber: nome...@joachim-breitner.de  • GPG-Key: 0x4743206C
  Debian Developer: nome...@debian.org


signature.asc
Description: This is a digitally signed message part
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] question about indentation conventions

[Sturdy, Ian]

I always preferred (I think going back to my lisp days)

foo x y
  z

indenting subsequent arguments to the same level as the first, but I have not 
convinced haskell-mode to do that for me. (The general rule here being that 
similar things should be at the same indent, which will always result in 
subexpressions being further indented, but is somewhat more specific.)

The case I never quite know what to do with is a series of expressions 
connected with operators, e.g.

foo
<|> bar
<|> baz

Leaving operators at the beginning of lines (rather than trailing the previous 
line) seems preferable, but does one (where the layout rules apply) align the 
operator or the function? (the alternative being, if your mail client does not 
make a mess of it with a variable-width font)

foo
<|> bar
<|> baz

~IRS

From: haskell-cafe-boun...@haskell.org [haskell-cafe-boun...@haskell.org] on 
behalf of Richard Cobbe [co...@ccs.neu.edu]
Sent: Monday, July 01, 2013 8:00 AM
To: haskell-cafe@haskell.org
Subject: Re: [Haskell-cafe] question about indentation conventions

On Mon, Jul 01, 2013 at 05:18:39PM +1200, Richard A. O'Keefe wrote:
>
> It looked pretty explicit to me:
>
>   The golden rule of indentation
>   ...
>   you will do fairly well if you just remember a single rule:
>   Code which is part of some expression should be indented
>   further in than the beginning of that expression (even if
>   the expression is not the leftmost element of the line).
>
> This means for example that
>   f (g x
>   y
>   z)
> is OK but
>   f (g x
>   y z)
> is not.
>

Sure.  So my first question boils down to which of the two alternatives
below does the community prefer?  (To be clear about the intended
semantics: this is the application of the function f to the arguments x, y,
and z.)

f x
y
z

or

f x
 y
 z

Both are correct, in most contexts.

And then there's the second question: if the second alternative is
preferable, is there a way to get haskell-mode to do it automatically?  As
it is, it refuses to indent y any farther to the right than in the first
alternative.  I can space it in by hand, and then haskell-mode puts z under
y, but that's annoying, and it gets in the way of reindenting large regions
of code automatically.

Richard

___
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] Installing Z3 on OS X 10.8.4 ( Off topic )

[Brandon Allbery]

On Mon, Jul 1, 2013 at 8:34 AM, Johannes Waldmann <
waldm...@imn.htwk-leipzig.de> wrote:

> and note that the install script says:
>
> Z3 shared libraries were installed at /usr/local/lib, make sure this
> directory is in your LD_LIBRARY_PATH environment variable.
>

Only applicable on Linux (and setting the OS X equivalent of
LD_LIBRARY_PATH is an absolutely wonderful way to break your system). OS X
compiles full paths to shared objects into binaries, and provides a tool to
change them if the need arises (install_name_tool).

-- 
brandon s allbery kf8nh   sine nomine associates
allber...@gmail.com  ballb...@sinenomine.net
unix, openafs, kerberos, infrastructure, xmonadhttp://sinenomine.net
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] question about indentation conventions

[Brandon Allbery]

On Mon, Jul 1, 2013 at 3:43 AM, Tom Ellis <
tom-lists-haskell-cafe-2...@jaguarpaw.co.uk> wrote:

> > is OK but
> >   f (g x
> >   y z)
> > is not.
>
> It seems to me that this means
>
> f x1 x2
> x3 x4
>
> is not.  The OP was initially asking about this situation.
>

If you wrote that in a do, the compiler would insert a (>>) between the two
lines.

-- 
brandon s allbery kf8nh   sine nomine associates
allber...@gmail.com  ballb...@sinenomine.net
unix, openafs, kerberos, infrastructure, xmonadhttp://sinenomine.net
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] question about indentation conventions

[Tikhon Jelvis]

My current approach is not to have one rule for every case but rather to
indent however seems best for the particular code. For example, for
Parsec's <|>, I try to make the code look like a BNF grammar rather than
adhering to normal indentation conventions. Perhaps as a carry-over from my
C-style programming days, I usually have the operators at the end of the
line, but I put <|> at the beginning, several steps *left* of where it
would normally be, to get everything aligned nicely.

Similarly, I try to align things to show the structure of the code. For
example, if I have two similar function calls on top of each other, I try
to highlight the parallelism:

foo (Just $ a + b) Nothing
foo Nothing  (Just $ a + b)

The main idea is that I try to format my code not based on what the *code*
is but based on what it *means*. I don't know if this is entirely
reasonable, but I like it.

I've thought about writing an automatic indenting tool for Haskell (or,
more accurately, a pretty-printer) for another project I have, and this is
the main thing that threw me off. While automatic indentation might make
sense for less expressive languages (Google Go being an extreme example), I
think it would be too constraining for Haskell. After all, in reasonable
code, chances are that similar constructs end up meaning wildly different
things (especially with the advent of pervasive embedded DSLs), so the code
itself is a poor indicator of its own structure.

So this is really something of an aside, but I do not think that a
gofmt-style tool would be quite as useful for Haskell, and it certainly
does not replace good taste.
**


On Mon, Jul 1, 2013 at 9:34 AM, Sturdy, Ian  wrote:

> I always preferred (I think going back to my lisp days)
>
> foo x y
>   z
>
> indenting subsequent arguments to the same level as the first, but I have
> not convinced haskell-mode to do that for me. (The general rule here being
> that similar things should be at the same indent, which will always result
> in subexpressions being further indented, but is somewhat more specific.)
>
> The case I never quite know what to do with is a series of expressions
> connected with operators, e.g.
>
> foo
> <|> bar
> <|> baz
>
> Leaving operators at the beginning of lines (rather than trailing the
> previous line) seems preferable, but does one (where the layout rules
> apply) align the operator or the function? (the alternative being, if your
> mail client does not make a mess of it with a variable-width font)
>
> foo
> <|> bar
> <|> baz
>
> ~IRS
> 
> From: haskell-cafe-boun...@haskell.org [haskell-cafe-boun...@haskell.org]
> on behalf of Richard Cobbe [co...@ccs.neu.edu]
> Sent: Monday, July 01, 2013 8:00 AM
> To: haskell-cafe@haskell.org
> Subject: Re: [Haskell-cafe] question about indentation conventions
>
> On Mon, Jul 01, 2013 at 05:18:39PM +1200, Richard A. O'Keefe wrote:
> >
> > It looked pretty explicit to me:
> >
> >   The golden rule of indentation
> >   ...
> >   you will do fairly well if you just remember a single rule:
> >   Code which is part of some expression should be indented
> >   further in than the beginning of that expression (even if
> >   the expression is not the leftmost element of the line).
> >
> > This means for example that
> >   f (g x
> >   y
> >   z)
> > is OK but
> >   f (g x
> >   y z)
> > is not.
> >
>
> Sure.  So my first question boils down to which of the two alternatives
> below does the community prefer?  (To be clear about the intended
> semantics: this is the application of the function f to the arguments x, y,
> and z.)
>
> f x
> y
> z
>
> or
>
> f x
>  y
>  z
>
> Both are correct, in most contexts.
>
> And then there's the second question: if the second alternative is
> preferable, is there a way to get haskell-mode to do it automatically?  As
> it is, it refuses to indent y any farther to the right than in the first
> alternative.  I can space it in by hand, and then haskell-mode puts z under
> y, but that's annoying, and it gets in the way of reindenting large regions
> of code automatically.
>
> Richard
>
> ___
> 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
>
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] question about indentation conventions

[Brandon Allbery]

On Mon, Jul 1, 2013 at 9:56 AM, Tikhon Jelvis  wrote:

> I've thought about writing an automatic indenting tool for Haskell (or,
> more accurately, a pretty-printer) for another project I have, and this is
> the main thing that threw me off. While automatic indentation might make
> sense for less expressive languages (Google Go being an extreme example), I
> think it would be too constraining for Haskell. After all, in reasonable
> code, chances are that similar constructs end up meaning wildly different
> things (especially with the advent of pervasive embedded DSLs), so the code
> itself is a poor indicator of its own structure.
>

One might look at the history of the indentation modules for Emacs
haskell-mode. Short version: they gave up, tab iterates through the
possibilities because it's quite impossible to know which one is correct
without a *semantic*, not just syntactic, understanding of the code.
(Which, when you think about it, is pretty much par for the Haskell
language definition. See also the literally impossible brace insertion rule
of Haskell98.)

-- 
brandon s allbery kf8nh   sine nomine associates
allber...@gmail.com  ballb...@sinenomine.net
unix, openafs, kerberos, infrastructure, xmonadhttp://sinenomine.net
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] question about indentation conventions

[Tikhon Jelvis]

That's certainly true. As I mentioned, I was actually considering a
*pretty-printer* rather than an automatic indentation tool per se. The end
results are similar, but the pretty-printer is really only the latter part
of the problem: it's predicated on already having a valid AST.

My particular use case involved diffing and merging ASTs directly; this
means that I would have to somehow output the result in a human-readable
format. Moreover, the actual AST I was outputting could have been the
combination of two others, without any prior concrete syntax! I still
haven't worked out a good way to do this for Haskell (or, to be fair, any
other language).

But yeah, Haskell is pretty intractable as far as language grammars go. I
think this is a great compromise--I value language expressiveness over
tooling--but it certainly is a compromise.


On Mon, Jul 1, 2013 at 10:10 AM, Brandon Allbery wrote:

> On Mon, Jul 1, 2013 at 9:56 AM, Tikhon Jelvis  wrote:
>
>> I've thought about writing an automatic indenting tool for Haskell (or,
>> more accurately, a pretty-printer) for another project I have, and this is
>> the main thing that threw me off. While automatic indentation might make
>> sense for less expressive languages (Google Go being an extreme example), I
>> think it would be too constraining for Haskell. After all, in reasonable
>> code, chances are that similar constructs end up meaning wildly different
>> things (especially with the advent of pervasive embedded DSLs), so the code
>> itself is a poor indicator of its own structure.
>>
>
> One might look at the history of the indentation modules for Emacs
> haskell-mode. Short version: they gave up, tab iterates through the
> possibilities because it's quite impossible to know which one is correct
> without a *semantic*, not just syntactic, understanding of the code.
> (Which, when you think about it, is pretty much par for the Haskell
> language definition. See also the literally impossible brace insertion rule
> of Haskell98.)
>
> --
> brandon s allbery kf8nh   sine nomine
> associates
> allber...@gmail.com
> ballb...@sinenomine.net
> unix, openafs, kerberos, infrastructure, xmonad
> http://sinenomine.net
>
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Installing Z3 on OS X 10.8.4 ( Off topic )

[Levent Erkok]

SBV should be able to pick up Z3 from your path; make sure the "z3"
executable is in it and you can invoke it from your shell. Alternatively,
you can use the SBV_Z3 environment variable to point to the executable
itself, if adding it to your path is not desirable for whatever reason.

Let me know if you still have issues.

-Levent.


On Mon, Jul 1, 2013 at 5:34 AM, Johannes Waldmann <
waldm...@imn.htwk-leipzig.de> wrote:

> > Unable to locate executable for z3
>
> well, do you really have z3 in the $PATH?
> what does 'which z3' answer?
>
> I used this for installation of z3:
> python scripts/mk_make.py --prefix=/usr/local
>
> and note that the install script says:
>
> Z3 shared libraries were installed at /usr/local/lib, make sure this
> directory is in your LD_LIBRARY_PATH environment variable.
>
> - J.W.
>
>
>
> ___
> 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

[Haskell-cafe] "Casting" newtype to base type?

[Vlatko Basic]

Hello Cafe!

I had a (simplified) record

  data P = P {
a :: String,
b :: String,
c :: IO String
} deriving (Show, Eq)

but to get automatic deriving of 'Show' and 'Eq' for 'data P' I have created 
'newtype IOS' and its 'Show' and 'Eq' instances


  newtype IOS = IO String
  instance Show (IOS) where show _ = "(IO String) function"
  instance Eq   (IOS) where _ == _ = True

(the easiest 'instance Show (IO String) where ...' produces "orphan instance")

and changed 'data P' to

  data P = P {
a :: String,
b :: String,
c :: IOS
} deriving (Show, Eq)

but now when I try to set 'c' field in

  fun :: FilePath -> P -> IO P
  fun path p = do
b <- doesFileExist path
...
return $ p {c = readFile path}

I get error
  Couldn't match expected type `IOS' with actual type `IO String'

which is correct.

So, the question is:

  Is it possible to somehow "cast" 'IO String' to 'IOS',
  or in some other way set 'c' field to an 'IO String' function
  so that it can be later used such as 'content <- c p'.



Thanks

___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] "Casting" newtype to base type?

[Frerich Raabe]

Am 7/1/2013 5:07 PM, schrieb Vlatko Basic:

to get automatic deriving of 'Show' and 'Eq' for 'data P' I have
created 'newtype IOS' and its 'Show' and 'Eq' instances

   newtype IOS = IO String


What you really want is

  newtype IOS = IOS (IO String)

I.e. a IOS value "wraps" an IO String.


   data P = P {
 a :: String,
 b :: String,
 c :: IOS
 } deriving (Show, Eq)

but now when I try to set 'c' field in

   fun :: FilePath -> P -> IO P
   fun path p = do
 b <- doesFileExist path
 ...
 return $ p {c = readFile path}

I get error
   Couldn't match expected type `IOS' with actual type `IO String'

which is correct.

So, the question is:

   Is it possible to somehow "cast" 'IO String' to 'IOS'


With the change to your 'newtype', you could use

  return $ p {c = IOS (readFile path)}

instead.

--
Frerich Raabe - ra...@froglogic.com
www.froglogic.com - Multi-Platform GUI Testing


___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] "Casting" newtype to base type?

[Tom Ellis]

On Mon, Jul 01, 2013 at 05:07:00PM +0200, Vlatko Basic wrote:
> Hello Cafe!
> 
> I had a (simplified) record
> 
>   data P = P {
> a :: String,
> b :: String,
> c :: IO String
> } deriving (Show, Eq)
> 
> but to get automatic deriving of 'Show' and 'Eq' for 'data P' I have
> created 'newtype IOS' and its 'Show' and 'Eq' instances
> 
>   newtype IOS = IO String
>   instance Show (IOS) where show _ = "(IO String) function"
>   instance Eq   (IOS) where _ == _ = True

An Eq instance for something containing IO is bound to lead to puzzlement
somewhere down the line.  I think you're better off defining something like

data P_lesser = P_lesser {
a_lesser :: String,
b_lesser :: String
} deriving (Show, Eq)

to_lesser p = P_lesser (a p) (b p)

and just factoring everything through "to_lesser" when you want to compare
or show.

Tom

___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Spam on list??

[Tom Ellis]

Yeah I'm getting stuff from j...@eukor.com every time I post.

___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] "Casting" newtype to base type?

[Malcolm Wallace]

On 1 Jul 2013, at 16:07, Vlatko Basic wrote:

> I had a (simplified) record
> 
>  data P = P {
>a :: String,
>b :: String,
>c :: IO String
>} deriving (Show, Eq)
> 
> but to get automatic deriving of 'Show' and 'Eq' for 'data P' I have created 
> 'newtype IOS' and its 'Show' and 'Eq' instances
> 
>  newtype IOS = IO String

Not quite!  That is a newtype'd String, not a newtype's (IO String).  Try this:

newtype IOS = IOS (IO String)

> but now when I try to set 'c' field in
> 
>return $ p {c = readFile path}
> 
> I get error
>  Couldn't match expected type `IOS' with actual type `IO String'

Use the newtype constructor to convert an IO String -> IOS.

return $ p {c = IOS $ readFile path}

Regards,
Malcolm
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

[Haskell-cafe] Spam on list??

[Vlatko Basic]

Title: 인증페이지시안1

  
  
Anybody else getting this spam emails from j...@eukor.com every time
  a message is sent to Cafe?


 Original Message 
  Subject: Re: [Haskell-cafe] "Casting" newtype to base type?
  From: j...@eukor.com 
  To: me
  Date: 01.07.2013 17:07



  
  
  
  
  

  

  
 
 
  
  
 
 
 
 
  
  
 

 
 
 

  
  
 

 

  

 
  
  

  


  
  

  


  
  
 
  

  
   

  

  
  
 

  

 
  
  
 

  
  
 

  

  
 

  
  
 

  

  

 
  
  
 

 

  
  
 
 
  
  
 

  
  
 

  

  
  
 

  
  
 

 

  

 
  
  

  


  

  

  
  

  

  


  

  
  
 

  

 
  
  
 

  
  
 

  

  


  
  
 

  

  

 
  
  
 

 

  
  
 
 
  
  
 

  
  
 
  
  
 

 

 

 

 

  

  
  
  

  


___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Spam on list??

[Brandon Allbery]

On Mon, Jul 1, 2013 at 11:19 AM, Vlatko Basic wrote:

>  Anybody else getting this spam emails from j...@eukor.com every time a
> message is sent to Cafe?
>

Yes, and I'm hoping a list admin steps in soon.

The irony is, it's their *anti*spam filter. They decided to use one of
those obnoxious whitelisting systems that requires all senders to register
with it before it will pass on their mail... but didn't exclude mailing
lists from this. Mailing lists, of course, can't authenticate, so they're
sending all these image-heavy "please whitelist yourself" messages in
Korean to the list submission address *and* not seeing any actual list
traffic.

This is one of the reasons I sometimes wish that use of an active spam
whitelist like this were grounds for disabling the user's email account.
They can't even tell what kind of mess they're making.

-- 
brandon s allbery kf8nh   sine nomine associates
allber...@gmail.com  ballb...@sinenomine.net
unix, openafs, kerberos, infrastructure, xmonadhttp://sinenomine.net
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Subclass or no subclass?

[Patrick Browne]

On 30/06/13, Dan Burton   wrote:I am not trying to say "every building is a shelter", rather "anything that is a building must provide sheltering services".

Well if it walks like a shelter and quacks like a shelter... /shrugOne of the nice things about OO is the
intuitive nature of the is-a relation between class and instance 
(forgetting
hierarchies for the moment). I suggest that an intuitive interpretation of the 
Haskell
class–instance relation might be *acts-as*. For example, a car or a bus could 
afford
transport once they have a move operation. This is an intuitive view for
 design;
it does not reflect the language level function of handling ad-hoc 
polymorphism. Also it reifies the type class, which AFAIK does not exist 
at run time.
 Tá an teachtaireacht seo scanta ó thaobh ábhar agus víreas ag Seirbhís Scanta Ríomhphost de chuid Seirbhísí Faisnéise, ITBÁC agus meastar í a bheith slán.  http://www.dit.ie
This message has been scanned for content and viruses by the DIT Information Services E-Mail Scanning Service, and is believed to be clean.  http://www.dit.ie



___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Subclass or no subclass?

[Darren Grant]

Here's another thought (not my own):

Abstractions can be classified based on where responsibility lies. Popular
languages implementing interface composition expect the caller to know
almost nothing about the concrete details while the callee has to handle
all concrete permutations. Conversely, the sort of abstraction we see in
typeclasses, much like those in c++ template programming, require the
client to dictate concrete details that satisfy the callee requirements.

Cheers,
Darren
On 2013-07-01 9:08 AM, "Patrick Browne"  wrote:

> On 30/06/13, *Dan Burton *  wrote:
>
> I am not trying to say "every building is a shelter", rather "anything
>> that is a building must provide sheltering services".
>
>
> Well if it walks like a shelter and quacks like a shelter... /shrug
>
> One of the nice things about OO is the intuitive nature of the is-a
> relation between class and instance (forgetting hierarchies for the
> moment). I suggest that an intuitive interpretation of the  Haskell
> class–instance relation might be *acts-as*. For example, a car or a bus
> could afford transport once they have a move operation. This is an
> intuitive view for design; it does not reflect the language level function
> of handling ad-hoc polymorphism. Also it reifies the type class, which
> AFAIK does not exist at run time.
>
>
>
> Tá an teachtaireacht seo scanta ó thaobh ábhar agus víreas ag Seirbhís
> Scanta Ríomhphost de chuid Seirbhísí Faisnéise, ITBÁC agus meastar í a
> bheith slán. http://www.dit.ie
> This message has been scanned for content and viruses by the DIT
> Information Services E-Mail Scanning Service, and is believed to be clean.
> http://www.dit.ie
> ___
> 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] "Casting" newtype to base type?

[Vlatko Basic]

Hi Wallace,

yes, indeed. Now I see I mixed newtype with type in declaration, and forgot the 
first one is a constructor.



 Original Message  
Subject: Re: [Haskell-cafe] "Casting" newtype to base type?
From: Malcolm Wallace 
To: vlatko.ba...@gmail.com
Cc: Haskell-Cafe 
Date: 01.07.2013 17:24



On 1 Jul 2013, at 16:07, Vlatko Basic wrote:


I had a (simplified) record

  data P = P {
a :: String,
b :: String,
c :: IO String
} deriving (Show, Eq)

but to get automatic deriving of 'Show' and 'Eq' for 'data P' I have created 
'newtype IOS' and its 'Show' and 'Eq' instances

  newtype IOS = IO String


Not quite!  That is a newtype'd String, not a newtype's (IO String).  Try this:

 newtype IOS = IOS (IO String)


but now when I try to set 'c' field in

return $ p {c = readFile path}

I get error
  Couldn't match expected type `IOS' with actual type `IO String'


Use the newtype constructor to convert an IO String -> IOS.

 return $ p {c = IOS $ readFile path}

Regards,
 Malcolm



___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] "Casting" newtype to base type?

[Vlatko Basic]

I'm experimenting. The IO field is just a helper field, so it shouldn't have any 
consequences.



 Original Message  
Subject: Re: [Haskell-cafe] "Casting" newtype to base type?
From: Tom Ellis 
To: haskell-cafe@haskell.org
Date: 01.07.2013 17:24


On Mon, Jul 01, 2013 at 05:07:00PM +0200, Vlatko Basic wrote:

Hello Cafe!

I had a (simplified) record

   data P = P {
 a :: String,
 b :: String,
 c :: IO String
 } deriving (Show, Eq)

but to get automatic deriving of 'Show' and 'Eq' for 'data P' I have
created 'newtype IOS' and its 'Show' and 'Eq' instances

   newtype IOS = IO String
   instance Show (IOS) where show _ = "(IO String) function"
   instance Eq   (IOS) where _ == _ = True


An Eq instance for something containing IO is bound to lead to puzzlement
somewhere down the line.  I think you're better off defining something like

 data P_lesser = P_lesser {
 a_lesser :: String,
 b_lesser :: String
 } deriving (Show, Eq)

 to_lesser p = P_lesser (a p) (b p)

and just factoring everything through "to_lesser" when you want to compare
or show.

Tom

___
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] ANNOUNCE: module-management-0.9.3 - clean import lists, split and merge modules

[David Fox]

On Sat, Jun 29, 2013 at 12:09 PM, David Fox  wrote:
> I've just uploaded version 0.10, which corrects some formatting bugs
> and incorporates most of the changes suggested in this thread.  Please
> give it a try!

Version 0.10.1 is now available - it should build with GHC 7.4.1,
fixes more formatting bugs, includes the unit test input data and
debian/changelog.  The next release will address people's concerns
about the signature of the splitModule function.  It will take a
function defining how to map symbols to module names, so people can
define their own splits.  It will also return a set of values
describing what it did.

Should I keep posting updates in this thread?

___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] ANNOUNCE: module-management-0.9.3 - clean import lists, split and merge modules

[Oliver Charles]

On 07/01/2013 08:38 PM, David Fox wrote:
> Should I keep posting updates in this thread?

Yes please, I'm interested in following this development! That, or get
yourself a blog and let us all know where to point our RSS readers.

- Ollie




signature.asc
Description: OpenPGP digital signature
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

[Haskell-cafe] cabal-dev: installing/running with profiling enabled

[Ömer Sinan Ağacan]

Hi all,

I want to profile a Haskell program. I have tons of libraries
installed without profiling enabled, and some of them are installed
with my Linux distribution's package mangaer.

So I tried installing the program in a fresh cabal-dev environment
with profiling enabled, so that all dependencies would be also
installed with profiling enabled. But for some reason even after
installing with `cabal-dev install --enable-executable-profiling
-prof` I still can't run this program with `caba-dev/bin/program +RTS
-p`, it fails with 'program: the flag -p requires the program to be
built with -prof'.

Can anyone help me on installing/running in cabal-dev with profiling enabled?


---
Ömer Sinan Ağacan
http://osa1.net

___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] some questions about Template Haskell

[TP]

John Lato wrote:

> The problem isn't the output of nameBase, it's the input parameter 'n'. 
> In your example, you've created a function that takes input (a Name) and
> generates code based upon that input.  In order to lift a value (n) from
> an ordinary context into a quote, it needs a Lift instance.

Thanks John.
Ok I can understand that a Lift instance is needed, but to use the lift 
function below, we also need a Lift instance for the return of (nameBase n), 
because lift is a function that operates on instances of the Lift typeclass:

> :i lift
class Lift t where
  lift :: t -> Q Exp

And it is indeed the case:
> :i Lift
[...]
instance Lift a => Lift [a]
instance Lift Char

And as I have shown on a small example, lift and [||] return about the same 
result:

> runQ $ lift "u"
ListE [LitE (CharL 'u')
> runQ $ [| "u" |]
LitE (StringL "u")

So what is the difference between lift and [||]?
Although I feel stupid, I cannot lie and claim I have understood.

> Perhaps it helps if you think about what a quote does: it allows you to
> write essentially a string of Haskell code that is converted into an AST.
>  For this to work, the quote parser needs to know how to generate the AST
> for an identifier.  Like much of Haskell, it's type-driven.  For
> identifiers in scope from imports, TH simply generates a variable with the
> correct name.  But for data, the parser needs a way to generate an AST
> representation, which is what Lift is for.

Ok, I think I understand that (we need some method to transform a value at 
data level in a token of an AST), but it seems to me it does not answer my 
question above. But I am probably wrong.

Thanks

TP


___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] cabal-dev: installing/running with profiling enabled

[Rogan Creswick]

Hi Ömer,

I've replied in-line below.

On Mon, Jul 1, 2013 at 2:34 PM, Ömer Sinan Ağacan wrote:

> So I tried installing the program in a fresh cabal-dev environment
> with profiling enabled, so that all dependencies would be also
> installed with profiling enabled. But for some reason even after
> installing with `cabal-dev install --enable-executable-profiling
> -prof` I still can't run this program with `caba-dev/bin/program +RTS
> -p`, it fails with 'program: the flag -p requires the program to be
> built with -prof'.
>

Because you're installing libraries (into the cabal-dev sandbox) you'll
also need to add the --enable-library-profiling flag, in addition to the
--enable-executable-profiling flag.  Cabal-dev could infer the former from
the later, but we haven't done that (this doesn't seem to come up very
often).

I don'th think the -prof flag is necessary; but if it is, then it may also
be misinterpreted by cabal-dev; generally, you need to pass flags that only
use a single leading "-" to cabal-dev with the --flags=... option. (eg:
'cabal-dev install --enable-library-profiling --enable-executable-profiling
--flags=-prof'


This command worked for me:

$ cabal-dev install --enable-library-profiling --enable-executable-profiling

Note that you must remove the existing cabal-dev sandbox directory before
running that command (or the installed dependencies that were built without
library profiling can cause the build to fail.

--Rogan
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] question about indentation conventions

[Richard A. O'Keefe]

On 2/07/2013, at 12:00 AM, Richard Cobbe wrote:

> Sure.  So my first question boils down to which of the two alternatives
> below does the community prefer?  (To be clear about the intended
> semantics: this is the application of the function f to the arguments x, y,
> and z.)
> 
>f x
>y
>z

This (a) clearly violates the Golden Rule of Indentation
 and (b) Goes out of its way to confuse human readers.
I do not know any indenting program that would tolerate
such a layout for C or Lisp.

> or
> 
>f x
> y
> z
> 
> Both are correct, in most contexts.

What part of "y and z are PARTS of f x y z and so SHOULD BE INDENTED
relative to the whole expression" is hard to understand?

If by "correct" you mean "will not confuse a Haskell parser",
you're right.  If you mean "will not dangerously mislead human
readers", only the second form is acceptable.

I do not trust any program to do my indentation.
And let's face it, if your Haskell functions are big
enough that manual indentation is a big issue, they
are too big.



___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] question about indentation conventions

[Richard Cobbe]

On Sun, Jun 30, 2013 at 07:53:08PM -0400, Richard Cobbe wrote:

> Two questions:

And what I've concluded by reading this thread:

> 1) Are there wide-spread conventions in the Haskell community for how to
> indent an application expression that's split across multiple lines?

Well, there's general consensus in favor of indenting the continuing lines,
but not a lot of consensus on how much, etc.  Not surprising, and that's
OK.  Infix operators are more complicated.

> 2) If there is such a convention, how do I make Emacs's haskell-mode do it?

Doesn't seem to be possible, unless you're in a "do" block.

To be clear: I wasn't asking how to make Emacs do all of my indentation
automatically, as it can in Lisp and C modes.  I realize that isn't
possible.

But since haskell-mode doesn't have very good support for the style I
personally prefer (which is, in fact, consistent with Richard O'Keefe's
favorite rule), I wondered if that might indicate that the community
prefers a different style.  Apparently not.

Thanks to all who responded; it's been an interesting (if occasionally
overly excited) discussion.

Richard

___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] some questions about Template Haskell

[adam vogt]

On Mon, Jul 1, 2013 at 5:42 PM, TP  wrote:
> So what is the difference between lift and [||]?
> Although I feel stupid, I cannot lie and claim I have understood.

Hi TP,

Sometimes [| |] does need to call lift. If for some reason the
original lift wasn't exported, you could define:

myLift x = [| x |]

But if you have enough $( ) splices to balance out the [| |], there is
no lift involved:

myId1 x = $( [| x |] )
myId2 x = [| $(x) |]


I think your first example is supposed to do:

*Pr> let x = 5 in $(pr 'x)
x = 5

That's possible if you had defined pr as:

pr n = [| putStrLn $ $(lift (nameBase n)) ++ " = " ++ show $(varE n) |]

If there were no [| |] quotes, but still the ' syntax for getting a
Name, it would still be possible to define pr:

pr2 n
  = varE 'putStrLn `appE`
  (infixE (Just (lift (nameBase n))) (varE '(++))
 (Just
(infixE (Just (lift " = ")) (varE '(++))
   (Just (appE (varE 'show) (varE n))

--
Adam

___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] question about indentation conventions

[Patrick Mylund Nielsen]

I prefer the other style--as do others, evidently (see the example in my
first reply.) I agree that this was a good discussion, but let's not
conclude so easily that the entire community is in favor of one thing or
the other.


On Mon, Jul 1, 2013 at 8:24 PM, Richard Cobbe  wrote:

> On Sun, Jun 30, 2013 at 07:53:08PM -0400, Richard Cobbe wrote:
>
> > Two questions:
>
> And what I've concluded by reading this thread:
>
> > 1) Are there wide-spread conventions in the Haskell community for how to
> > indent an application expression that's split across multiple lines?
>
> Well, there's general consensus in favor of indenting the continuing lines,
> but not a lot of consensus on how much, etc.  Not surprising, and that's
> OK.  Infix operators are more complicated.
>
> > 2) If there is such a convention, how do I make Emacs's haskell-mode do
> it?
>
> Doesn't seem to be possible, unless you're in a "do" block.
>
> To be clear: I wasn't asking how to make Emacs do all of my indentation
> automatically, as it can in Lisp and C modes.  I realize that isn't
> possible.
>
> But since haskell-mode doesn't have very good support for the style I
> personally prefer (which is, in fact, consistent with Richard O'Keefe's
> favorite rule), I wondered if that might indicate that the community
> prefers a different style.  Apparently not.
>
> Thanks to all who responded; it's been an interesting (if occasionally
> overly excited) discussion.
>
> Richard
>
> ___
> 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] cabal-dev: installing/running with profiling enabled

[Ömer Sinan Ağacan]

Hi Rogan,

Thanks for your reply.

> I don'th think the -prof flag is necessary; but if it is, then it may also
> be misinterpreted by cabal-dev; generally, you need to pass flags that only
> use a single leading "-" to cabal-dev with the --flags=... option. (eg:
> 'cabal-dev install --enable-library-profiling --enable-executable-profiling
> --flags=-prof'
>
>
> This command worked for me:
>
> $ cabal-dev install --enable-library-profiling --enable-executable-profiling

OK, so I removed `cabal-dev` directory, and installed again with this
command. But it still failed with same error message("the flag -p
requires the program to be built with -prof").

Then I also tried removing cabal-dev again and installing again but
this time with extra `--flags=-prof` parameter. Failed with same
error.

Just to be sure I created a new cabal project with only one file:
'Hello.hs' with contents 'main = putStrLn "hello"' and tried to
install it with cabal-dev. And `./cabal-dev-/bin/Hello +RTS -p` failed
with same error again.

Maybe something wrong with my system? My first thought was maybe
cabal-dev is using some pre-installed library, and it's not
recompiling the whole world for each sandbox. But I don't know how to
check this.

Any ideas on that?

Thanks,

---
Ömer Sinan Ağacan
http://osa1.net

___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Installing Z3 on OS X 10.8.4 ( Off topic )

[mukesh tiwari]

Thank you for your response. Now it's working.

-Mukesh Tiwari


On Mon, Jul 1, 2013 at 8:32 PM, Levent Erkok  wrote:

> SBV should be able to pick up Z3 from your path; make sure the "z3"
> executable is in it and you can invoke it from your shell. Alternatively,
> you can use the SBV_Z3 environment variable to point to the executable
> itself, if adding it to your path is not desirable for whatever reason.
>
> Let me know if you still have issues.
>
> -Levent.
>
>
> On Mon, Jul 1, 2013 at 5:34 AM, Johannes Waldmann <
> waldm...@imn.htwk-leipzig.de> wrote:
>
>> > Unable to locate executable for z3
>>
>> well, do you really have z3 in the $PATH?
>> what does 'which z3' answer?
>>
>> I used this for installation of z3:
>> python scripts/mk_make.py --prefix=/usr/local
>>
>> and note that the install script says:
>>
>> Z3 shared libraries were installed at /usr/local/lib, make sure this
>> directory is in your LD_LIBRARY_PATH environment variable.
>>
>> - J.W.
>>
>>
>>
>> ___
>> 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
>
>
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe