Create from inferred usage

[dillonkearns]

For reference, here's the work-in-progress from our live stream today. I'll update this thread as I finish these todos.

Current State

Todos

• Don't suggest for unresolved type references - only for value functions (for this PR, revisit in the future)
• Don't suggest fix for qualified references
• Make sure cursor focus goes through argument names so you can tab through to change them
  • Make declaration fix does it
  • It's called a Template (see TemplateManager)
• Add newline for proper formatting for creating function
• Location - insert it right below call site function body, not at bottom

Maybe now, maybe defer?

• Infer types based on values passed in?
• Use argument template names based on types, like create from declaration?

[dillonkearns]

A fun reference, Kolja shared this PR with me where he implements the same functionality for the Elm languages server:

elm-tooling/elm-language-server#319

[ajalt]

You can generate type-based parameter names like this:

val inference = element.findInference() ?: return
val callExpr = element.parent as? ElmFunctionCallExpr ?: return
val argsTys = callExpr.arguments.map { inference.elementType(it) }
val parameters = argsTys.joinToString(" ") { it.renderParam() }

And then, if argsTys isn't empty, you can generate a type annotation the way the MakeAnnotationIntention does.

"$s : ${TyFunction(args, TyUnknown()).renderedText(elmFile = element.elmFile).replace("→", "->")}"

[klazuka]

This will fix #661

[cies]

Hi @dillonkearns ! I took over the stewardship of this repo. I find this PR nice to merge. Do you want to address the point @ajalt made and extend on this feature before you take it out of "draft" and I merge it? Or would you also promote this PR in it's current shape from draft to ready-to-merge?