[Agda] Impossible proofs about where blocks?

[Andreas Abel]

So it seems easiest to patch the std.lib. and put the local functions to 
Data.Digit.toDigit into a module as Ulf described.

On 6/16/11 1:26 AM, Daniel Peebles wrote:
> Let's say I'm writing a proof with a goal type of:
>
> Goal: (fromℕ
>         (peanoInduction (λ {x'} _ → ℕ) 0 (λ {.x} {.m} → Nsuc)
>          (toPeano (x ∷ xs)))
>         | (.Data.Digit._.helper 0
>            (peanoInduction (λ {x'} _ → ℕ) 0 (λ {.x} {.m} → Nsuc)
>             (toPeano (x ∷ xs)))
>            (peanoInduction (λ {x'} _ → ℕ) 0 (λ {.x} {.m} → Nsuc)
>             (toPeano (x ∷ xs)))
>    ...
>
> Note that it will not proceed in normalizing the goal type unless I can
> match on the result of the expression after the pipe. Unfortunately,
> said expression lives within a where block in a module that's out of my
> control, so I can't see it at all, to proceed on the proof. As far as I
> can understand, assuming there aren't completely different approaches to
> the proof, this makes my proof actually impossible. Am I correct?
>
> Now, the ._.helper notation looks like the helper is secretly living
> inside an anonymous module that the where block created. Given the
> recent change that made datatypes into modules, would it be worthwhile
> or problematic to make all value declarations with where blocks into
> explicit modules as well, so that we can open them and prove things
> about whatever happened inside? Would this cause problems in other ways?
>
> Even if my suggestion isn't valid, it seems like it'd be good to have a
> good answer for this kind of situation. Or is there already some
> solution that I'm missing?
>
> Thanks,
> Dan
>
>
>
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