[Haskell-cafe] haskell gsoc proposal for richer numerical type classes and supporting algorithms

[Stephen Tetley]

Hi Carter

The proposal is interesting - but maybe there is not a great community
benefit to a 'covers everything' library considering Henning
Thielemann and others 'numeric prelude' already exists:

http://hackage.haskell.org/package/numeric-prelude

As a not especially mathematically inclined Haskell programmer who
delves into geometry at least, the current Num class is certainly a
problem even for me. I'd certainly welcome a small but more 'sound'
set of numeric classes - Jerzy Karczmarczuk has presented such a
library in various papers - this one (in French) lists the full code:

http://users.info.unicaen.fr/~karczma/arpap/pareseq.pdf

At the moment I use the normal Num class (ho-hum) plus Conal Elliott's
VectorSpace package to get similar.

Sectioning the Prelude would be useful (perhaps boring) work to add
onto a GSoC project that replaces some of its machinery. Currently if
one wants to avoid the Prelude's Num, one then has to import say the
monad stuff by hand. Similarly, if one wants to hide the monads, if
they have parameterized monads instead, they lose all the Num codes.
Some suitably defined import modules would be very handy e.g.:

{-# LANGUAGE NoImplicitPrelude #-}

module XYZ where

import PreludeWithoutNum

...


Best wishes

Stephen