[Haskell-cafe] vector-space and standard API for vectors

wren ng thornton wren at freegeek.org
Sat Oct 23 19:57:08 EDT 2010

On 10/23/10 7:52 PM, wren ng thornton wrote:
> I'd argue that neither usage is "primary", and therefore the best
> solution is actually to have three classes (neutral, additive, and
> multiplicative) with two functors (additive->neutral,
> multiplicative->neutral) to connect them[1].[...]
> [1] the Exp/Log isomorphism between additive and multiplicative are not
> considered here, as there are good arguments both for using newtypes and
> for not using them.

Of course, I mean "functor" in the category theoretic sense (monoid 
homomorphisms, in this case). Not in the type class sense, per se 
(though all newtypes are/can be Functors).

Live well,

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