Cond indentation/readabliity, continuation syntax proposal for expr

Questions & Help General Questions
11

Sorry for resurrecting an old thread, but I was excited to see @didibus mention using commas here. I do exactly this. These days I’m an engineering team of one at CollBox, so I don’t yet know how this will go over with other engineers, but I’ve been test-driving this for a few months now and I’m pretty happy with it.

I actually use commas whenever I want to violate the normal Clojure indentation standards. Typically that comes in three cases:

  1. The cond example described above:
(cond
  (extremely-long-condition with some lengthy args)
  , :foo
  (another-extremely-long-condition here)
  , :bar)

But that’s probably my rarest usage of it. More commonly I use this with…

  1. Datomic queries with multiple :where clauses that I want to align, but I like having them indented after the :where keyword like the rest of the key-value “pairs”:
(datomic.api/q '[:find ?user
                 :in $ ?email
                 :where [?user :user/email ?email]
                 ,      [?user :user/role :user.role/admin]]
               db email)

(And yes, I am aware of the map syntax for q.)

  1. Compactly-aligned let bindings where I have one or two lengthy names I’m binding and I don’t want to shift all of the values annoyingly far right:
(let [name       "Bilbo Baggins"
      email      "bilbo@shire.org"
      confirmed? false
      something-annoyingly-long
      ,          42]
  ; ...
  )

I’m sure somebody will say this is the worst thing ever, but I firmly believe that indentation impacts readability, and while the comma trick isn’t exactly beautiful, it lets me express the patterns in the code that I want a reader to notice, without making me fight my editor’s indentation features, and it calls out the non-standard indentation as being intentional.

1 Like