feat(compiler)!: Labeled and default arguments (#1623)

* feat(compiler)!: Labeled and default arguments

* graindocs

* remove formatting fixme

* make loc required

* Use helper for argument types

* impossible case instead of assert false

* use label name for generated options

* use more standard user unaccessible name

* standardize around call over apply

* rework error messages

* Add out of order use of argument in default value test

* add order test

Author: ospencer

compiler/graindoc/docblock.re

@@ -207,7 +207,10 @@ let output_for_throws = throws => {
 
 let types_for_function = (~ident, vd: Types.value_description) => {
   switch (Ctype.repr(vd.val_type).desc) {
-  | TTyArrow(args, returns, _) => (Some(args), Some(returns))
+  | TTyArrow(args, returns, _) => (
+      Some(List.map(snd, args)),
+      Some(returns),
+    )
   | _ => (None, None)
   };
 };