Constraints on definition of `length` should be strengthened

[dominic at steinitz.org]

I am not sure what to make of the “documentation” to which you refer. For example, a type Tensor seems to be defined. Now you can tensor lots of things with some algebraic structure but most commonly vector fields and modules (modules in the mathematical sense that is). The type Tensor seems to have no relation to these and there is no prose giving an indication of the author’s intent. Perhaps we should be cautious about adducing other parts of the package as evidence?

> Already done mate.
> 
> https://hackage.haskell.org/package/hask-0/docs/Hask-Category.html#t:Either
> https://hackage.haskell.org/package/hask-0/docs/Hask-Category.html#t:Functor
> 
> Note the multiple Functor instances for Either and Coproduct. e.g.
> 
> - Functor * (* -> *) Either
> - Functor * * (Either a)
> etc etc
> 
> On 09/04/17 10:29, Henrik Nilsson wrote:
>> And of course, if, in a hypothetical future version of Haskell
>> where we could make all possible functor instances for tuples,
>> the question becomes: which one do we pick? The answer might well
>> be "none" (in the prelude, at least).

Dominic Steinitz
dominic at steinitz.org
http://idontgetoutmuch.wordpress.com