Add remaining instances for Comonad transformers

[skeate]

Description of the change

Adds ComonadAsk, ComonadEnv, and ComonadTraced instances for StoreT, EnvT, and TracedT

Closes #35

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Checklist:

• Added the change to the changelog's "Unreleased" section with a reference to this PR (e.g. "- Made a change (#0000)")
• Linked any existing issues or proposals that this pull request should close
• Updated or added relevant documentation
• Added a test for the contribution (if applicable)

[JordanMartinez]

🏓 @garyb

[garyb]

I did take a look at this, but I don't feel qualified to approve it, since I'm not that familiar with comonad patterns. Perhaps @MonoidMusician or @LiamGoodacre could chime in, I think they're more theorypilled than me? 😉

[MonoidMusician]

Yup, looks good to me! It’s doing the “obvious” thing, which is just the opposite of the usual monadic constructions.

[garyb]

Yup, looks good to me! It’s doing the “obvious” thing, which is just the opposite of the usual monadic constructions.

Ah okay. I did once implement some comonad stuff and it seemed way too trivial to be correct. I asked someone and they weren't sure if it was right either. 😄

[MonoidMusician]

Yeah, this is just lifting instances like ask = lift <<< ask in the monadic work, but it's ask = ask <<< lower here :)

[MonoidMusician]

Are we good to merge this btw?

[LiamGoodacre]

is this an implementation detail, or something to be exported? (It's currently being implicitly exported).

[skeate]

whoops, yeah this should not be exported