Re: [Haskell-cafe] Arrows for invertible programming: Notation, question

2005-12-29 Thread Alexey Rodriguez Yakushev 


On Dec 23, 2005, at 11:53, Arjen wrote:


On Fri, 23 Dec 2005, Joel Reymont wrote:

 Folks,

 I have been looking at the code for the Arrows for invertible
 programming paper (http://www.cs.ru.nl/A.vanWeelden/bi-arrows/) and
 I have a question about syntax. ghci surely does not like it.

I've updated the web page to say that is does not work with Hugs, GHCi 
or GHC -fgenerics, sorry for the confusion.
It really requires Generic Haskell (GH) 1.42. I never got GH working 
with GHC 6.4, so you also really need GHC 6.2.2. I think you can run 
the result of the GH preprocessor (using the right command line 
options) in GHCi or Hugs, but I'm not sure.


Once you have compiled your GH program (.ghs) into a haskell program 
(.hs), you can load it into ghci using the wrapper provided in 
build/bin/gh-ghci .




If anyone got GH working with GHC 6.4(+), please tell me how you did 
it.


To build GH with the 6.4 series of GHC you need to check out the 
sources from the subversion repository:


svn co 
https://svn.cs.uu.nl:12443/repos/Generic-Haskell/trunk/Generic-Haskell/



Cheers,

Alexey

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[Haskell-cafe] Arrows for invertible programming: Notation question

2005-12-23 Thread Joel Reymont 

Folks,

I have been looking at the code for the Arrows for invertible  
programming paper (http://www.cs.ru.nl/A.vanWeelden/bi-arrows/) and  
I have a question about syntax. ghci surely does not like it.


What does this mean and how do I make it compile?

mapl{|a, b|arr|} :: (mapl{|a, b|arr|}, ArrowChoice arr, BiArrow arr)  
= arr a b


Thanks, Joel

--
http://wagerlabs.com/


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Re: [Haskell-cafe] Arrows for invertible programming: Notation question

2005-12-23 Thread Ralf Hinze 
 What does this mean and how do I make it compile?
 
 mapl{|a, b|arr|} :: (mapl{|a, b|arr|}, ArrowChoice arr, BiArrow arr) = arr a 
 b

It's Generic Haskell source code, see

http://www.generic-haskell.org/

Generic Haskell is an extension of Haskell that supports generic programming.

Cheers, Ralf
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Re: [Haskell-cafe] Arrows for invertible programming: Notation question

2005-12-23 Thread Joel Reymont 
Is this something that can be compiled with GHC right now? I noticed - 
fgenerics but I think it does something else entirely.


On Dec 23, 2005, at 8:52 AM, Ralf Hinze wrote:


It's Generic Haskell source code, see

http://www.generic-haskell.org/

Generic Haskell is an extension of Haskell that supports generic  
programming.


--
http://wagerlabs.com/





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Re: [Haskell-cafe] Arrows for invertible programming: Notation question

2005-12-23 Thread Ralf Hinze 
 Is this something that can be compiled with GHC right now? I noticed - 
 fgenerics but I think it does something else entirely.

GH is a pre-compiler that takes GH code to Haskell code,
so this is a two-step process. -fgenerics turns derivable
type classes on (see Derivable type classes, Ralf Hinze
and Simon Peyton Jones, Haskell Workshop 2000, pp94-105).
The two are different but related ...

Cheers, Ralf
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Re: [Haskell-cafe] Arrows for invertible programming: Notation, question

2005-12-23 Thread Arjen 

On Fri, 23 Dec 2005, Joel Reymont wrote:

 Folks,

 I have been looking at the code for the Arrows for invertible
 programming paper (http://www.cs.ru.nl/A.vanWeelden/bi-arrows/) and
 I have a question about syntax. ghci surely does not like it.

I've updated the web page to say that is does not work with Hugs, GHCi 
or GHC -fgenerics, sorry for the confusion.
It really requires Generic Haskell (GH) 1.42. I never got GH working 
with GHC 6.4, so you also really need GHC 6.2.2. I think you can run the 
result of the GH preprocessor (using the right command line options) in 
GHCi or Hugs, but I'm not sure.


If anyone got GH working with GHC 6.4(+), please tell me how you did it.

 What does this mean and how do I make it compile?

 mapl{|a, b|arr|} :: (mapl{|a, b|arr|}, ArrowChoice arr, BiArrow arr)
 = arr a b

In GH this means: mapl is a polytypic (type-indexed in a and b) function 
that yields an arr(ow) from a to b. It is overloaded in ArrowChoice and 
BiArrow on the arr(ow). Because it is polytypic, it is also overloaded 
`in itself'. Most of the time GH does not require the last part 
explicitly, but sometimes it triggers a bug if you don't specify it.

The semantics of mapl can be found in the paper.

regards,
Arjen

   Thanks, Joel

 --
 http://wagerlabs.com/

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