Unboxed Rationals?

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Victor Miller

11 Jan 2012 11 Jan '12

11:38 a.m.

I have a program which does a lot of computations with Array's of rationals. In order to get better performance I'd like to use unboxed arrays, but, since (Ratio Int) isn't a primitive type this doesn't work. It occured to me that I could rewrite this using -fglasgow-exts where I represent a rational by (# Int, Int #). It isn't too hard to do this, but I'd like to know it it's already in some library out there, so that I can use something already existing. This is a more general problem that I have (I'm pretty new to Haskell) of finding a library to "do X". Victor

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Artyom Kazak

11 Jan 11 Jan

12:51 p.m.

You can use Data.Vector.Unboxed. There isn't an instance for Ratio a, but it is easy to write one, since it would be very similar to Complex a. http://hackage.haskell.org/packages/archive/vector/0.9.1/doc/html/Data-Vecto...

Artyom Kazak

noon

Also, uvector already supports unboxed Ratios: http://hackage.haskell.org/package/uvector In fact, I am surprised that Data.Vector doesn't have a Ratio instance, but has a Complex instance. Any ideas, why?

Roman Leshchinskiy

5:17 p.m.

On 11/01/2012, at 17:00, Artyom Kazak wrote:

...

In fact, I am surprised that Data.Vector doesn't have a Ratio instance, but has a Complex instance. Any ideas, why?

Nobody has asked for it so far. Roman

Yves Parès

12 Jan 12 Jan

6:14 a.m.

uvector is deprecated, its functionnalities has been ported into vector. 2012/1/11 Artyom Kazak

...

Also, uvector already supports unboxed Ratios: http://hackage.haskell.org/package/uvector

In fact, I am surprised that Data.Vector doesn't have a Ratio instance, but has a Complex instance. Any ideas, why?

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Artyom Kazak

4:01 p.m.

Yves Parès писал(а) в своём письме Thu, 12 Jan 2012 13:14:16 +0200:

...

uvector is deprecated, its functionnalities has been ported into vector.

Yes, but a Ratio a instance hasn't been ported. I admit that I have overlooked the “deprecated” warning, and agree that it is better to write an instance by yourself than use a deprecated package. Dead things should stay dead.

Roman Leshchinskiy

5:36 p.m.

On 12/01/2012, at 21:01, Artyom Kazak wrote:

...

Yves Parès писал(а) в своём письме Thu, 12 Jan 2012 13:14:16 +0200:

...
uvector is deprecated, its functionnalities has been ported into vector.

Yes, but a Ratio a instance hasn't been ported.

FWIW, vector isn't a port of uvector in any sense, shape or form. Rather, uvector was a fork of a very old version of an internal DPH package, whereas vector is a from-scratch implementation of arrays based on the experience gained while working on DPH. Vector is an open-source project and has a trac. If you need something, open a ticket or better yet, send me patches! Emails sometimes work, too :-) Roman

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Artyom Kazak
Roman Leshchinskiy
Victor Miller
Yves Parès