Simplify `case` if all branches are the same

[miniBill]

What the rule should do: Simplify case of expressions if all the branches are the same.

Example of things the rule would report:

 case err of
   Http.BadBody _ ->
    Task.fail err
  _ ->
    Task.fail err
--> Task.fail err

(this is real code, and is the result of other simplifications)

Example of things the rule would not report:

case res of
  Ok v -> v
  Err v -> v

Should this be part of the Simplify rule or should it be a new rule? Should be part of Simplify

I am looking for:

• Feedback
• Someone to implement it with/for me

[jfmengels]

This is something that we did earlier in the history of the rule and was (partially) removed in v2.0.19 (reasoning in the link). Let me know what you think.

[miniBill]

Ah, makes sense. It should have triggered though, because Http.BadBody comes from a dependency?

[jfmengels]

You're correct 🤔 I'll mark this as a bug, this will need some looking into.