Represent the arity of uncurried function definitions directly in the… (#7197)

* Represent the arity of uncurried function definitions directly in the AST.

* Use uncurried type for `@deriving(jsConverter)`

This goes towards making all arities explicit.

* Clean up arity in derive projector.

The arity is later overridden anyway, but being explicit can help cleaning up later on if `Function$` is removed entirely.

* Most of Untypeast is never used.

* More explicit translation for `Function$`.

Cosmetic change that will be needed later to remove `Function$`.

* Update CHANGELOG.md

Author: cristianoc

CHANGELOG.md

@@ -23,6 +23,7 @@
 - Ast cleanup: remove exp object and exp unreachable. https://github.com/rescript-lang/rescript/pull/7189
 - Ast cleanup: explicit representation for optional record fields in types. https://github.com/rescript-lang/rescript/pull/7190 https://github.com/rescript-lang/rescript/pull/7191
 - AST cleanup: first-class expression and patterns for records with optional fields. https://github.com/rescript-lang/rescript/pull/7192
+- AST cleanup: Represent the arity of uncurried function definitions directly in the AST. https://github.com/rescript-lang/rescript/pull/7197
 
 
 # 12.0.0-alpha.5

analysis/src/CompletionFrontEnd.ml

@@ -1318,7 +1318,7 @@ let completionWithParser1 ~currentFile ~debug ~offset ~path ~posCursor
             match exprToContextPath lhs with
             | Some contextPath -> setResult (Cpath (CPObj (contextPath, label)))
             | None -> ())
-        | Pexp_fun (lbl, defaultExpOpt, pat, e) ->
+        | Pexp_fun (lbl, defaultExpOpt, pat, e, _) ->
           let oldScope = !scope in
           (match (!processingFun, !currentCtxPath) with
           | None, Some ctxPath -> processingFun := Some (ctxPath, 0)