Coq: Fixing a recursive notation

Question

Below is a half-working simple recursive notation:

Universe ARG. Definition ARG := Type@{ARG}.
Parameter X: ARG.
Notation A := (fun x:ARG->ARG => fun y:x X => y).
Parameter P: ARG -> ARG.
Parameter s: P X.
Notation "[ x .. z u ]" := (x P .. (z P u) .. ) (at level 5, z, u at next level).
Check (A P (A P (A P s))). (* [A A A s]: P X *)
Print Grammar constr.
(*| "5" RIGHTA
  [ "["; NEXT; LIST1 NEXT; NEXT; "]"
  | "["; NEXT; NEXT; "]" ]*)
Check [A A A s]. (* Syntax error: [constr:operconstr] or [constr:operconstr] expected (in [constr:operconstr]). *)

As you see, Coq recognizes A P (A P (A P s)) as [A A A s]: P X but cannot parse [A A A s]. Where is the problem, what's the fix?

EDIT: Coq seems to require some "parsing aids" here. For example, the following works:

Notation "( x .. z [ u ] )" := (x P .. (z P u) .. ) (at level 5, z at next level).
Check (A A A [s]): P X.

As I'd like to get rid of the inner notation, the question remains open

Answer 1

The problem is that Coq <= 8.7 does not support recursive notations of the form x .. y z very well, and the fix is to download Coq master, or wait for Coq 8.8. Hugo Herbelin's fix, entitled Adding support for recursive notations of the form "x , .. , y , z", was merged on Aug 1, 2017.