Rationale for not aligning map values/let bindings

[jacobobryant]

(Continuing from #173 in a new issue)

I asked you at the conj about map value alignment and you said it could be done but you weren't planning to implement it. Also the readme says:

• vertical alignment of let forms and map literals are allowed
  • the choice is up to the author
  • [cljfmt option] :remove-multiple-non-indenting-spaces? = false
  • I have seen too many code examples where vertical alignment adds clarity

i.e. the formatter allows alignment, but it doesn't enforce alignment. SCS allows this snippet to go through formatting unchanged, for example:

{:first-key  1
 :second-key 2
 :third-key 3}

This is the other large benefit I've had from zprint. Most of the other Clojure devs in my company have used Cursive with settings enabled for aligning map values (don't remember about let bindings/don't know if Cursive supports that). However I use Vim, which doesn't have any reliable plugin support for doing that. So either I align the values manually (a constant source of friction), or we end up with maps that have partially aligned values (very ugly). zprint's been great since I can just let it do the alignment for me via pre-commit.

So similar to the other issue--obviously I'd love it if you'd be open to implementing map value/let binding alignment, but if not, I'd appreciate an expanded rationale + recommendations for what we should be doing. Should we just allow partially-aligned maps into the codebase? Should we have everyone disable their auto-align-map-forms settings?

[oakmac]

Sometimes vertically aligning map values improves readability, sometimes it does not. Standard Clojure Style leaves that choice up to the author.

In the early stages of this project I had some code that enforced one space between map literal values and I ran the formatter over several codebases to review the diff. I saw many changes to maps that did not improve readability and realized "this is never going to fly for all codebases, all the time."

It would be great if vertically-aligned maps were always good, or always bad. But I think it's just not the case for Clojure code.

I mentioned this on my comment on Issue #173: if this is a hard requirement for your team, zprint may be the better choice for you.

[oakmac]

Should we just allow partially-aligned maps into the codebase?

It might be possible for Standard Clojure Style to support "maps must use a single space between key/value pairs, or all values must be vertically aligned" (enforcing either / or - but not "partially aligned").

This would still leave the choice up to the author, but enforce consistency within the context of each map or let binding.

Off the top of my head, I am not sure how difficult this might be to program. Or if it would conflict with other rules. This idea is probably worth exploring to see how feasible it is.

[jacobobryant]

It might be possible for Standard Clojure Style to support "maps must use a single space between key/value pairs, or all values must be vertically aligned" (enforcing either / or - but not "partially aligned").

That would be really interesting. Definitely drop another comment here if you do experiment with that.