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Comment by pdimitar | Hacker News Reader

I keep hearing from people here and there to use Dhall.

Anybody has direct impressions?

Just took a quick look and the first example does that hateful thing with starting lines with commas. Even if that's just a convention thing it instantly makes me want to avoid it.

Just allow trailing commas at the end of lists. It's much less jarring and unfamiliar.

Trivial? Maybe. But my brain takes a while to adjust to new conventions and I do it way too frequently already.

You can have trailing commas just fine: https://github.com/dhall-lang/dhall-lang/pull/956

However, `dhall format` is _very_ opinionated, and will remove it.

Does dhall format have an opinion about commas at the start vs end of lines? What's the recommended style?

I formatted

  { foo = 3, bar = 4, baz = 5, verylongproperty = 6, dunnoneedsmoremore = 7, howmanytoforcealinebreak = 8 }

And it forces the comma at the beginning of the line, Haskell-style:

  { foo = 3
  , bar = 4
  , baz = 5
  , verylongproperty = 6
  , dunnoneedsmoremore = 7
  , howmanytoforcealinebreak = 8
  }

This will not diff well if you add a new row at the beginning. It's the same problem with non-trailing-commas, but moved to the front instead of the end.

IME people tend to just add stuff at the bottom. Doesn't help with ordered lists, though.

A few months ago I explored using Dhall and Jsonnet to re-write an Ansible playbook [0,1]. I wanted to like Dhall, but found the type system got in the way more than it helped, while Jsonnet was very productive and a huge improvement over YAML.

[0] https://www.kmr.me/posts/dhall_jsonnet

[1] https://github.com/retzkek/ansible-dhall-jsonnet

It's great if the system is built directly on top of it, e.g. spago. Not so much if you're trying to type yaml. Dhall is very opinionated, so trying to use it like TypeScript to type an untyped structure is... interesting.

E.g. for Kubernetes: https://github.com/dhall-lang/dhall-kubernetes

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