[Agda] Levels and Containers

[Andreas Abel]

Don't know (but I am not a user of Container).  Let's see if there is 
strong arguments for the current situation, and if not, please submit a 
pull request.

On 27.01.2017 20:50, Manuel Bärenz wrote:
> Dear Agda people, especially stdlib people,
>
> In the definition of Data.Container, is there a reason why the level of
> the container is the same as the level of the functor argument?
>
> The definition is:
>
> -- stdlib code
>
> record Container (ℓ : Level) : Set (suc ℓ) where
>   constructor _▷_
>   field
>     Shape    : Set ℓ
>     Position : Shape → Set ℓ
>
> open Container public
>
> -- The semantics ("extension") of a container.
>
> ⟦_⟧ : ∀ {ℓ} → Container ℓ → Set ℓ → Set ℓ
> ⟦ C ⟧ X = Σ[ s ∈ Shape C ] (Position C s → X)
>
> -- stlib code ends
>
> It's possible to generalise the last two lines to:
>
> ⟦_⟧ : ∀ {ℓ₁ ℓ₂} → Container ℓ₁ → Set ℓ₂ → Set (ℓ₁ ⊔ ℓ₂)
> ⟦ C ⟧ X = Σ[ s ∈ Shape C ] (Position C s → X)
>
> For my project, this would be great. (I've done that change in my local
> copy.) You have to make some type signatures slightly more verbose,
> otherwise there are unsolved metas, but it's not a big deal.
>
> Is there any deeper reason why the stdlib type signature is so special?
>
> Manuel
>
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-- 
Andreas Abel  <><      Du bist der geliebte Mensch.

Department of Computer Science and Engineering
Chalmers and Gothenburg University, Sweden

andreas.abel at gu.se
http://www.cse.chalmers.se/~abela/