Integrate build and documentation of Ltac2

Since Ltac2 cannot be put under the stdlib logical root (some file names
would clash), we move it to the `user-contrib` directory, to avoid adding
another hardcoded path in `coqinit.ml`, following a suggestion by @ejgallego.

Thanks to @Zimmi48 for the thorough documentation review and the
numerous suggestions.

1 files changed, 27 insertions, 0 deletions

diff --git a/test-suite/ltac2/example1.v b/test-suite/ltac2/example1.v
new file mode 100644
index 0000000000..023791050f
--- /dev/null
+++ b/test-suite/ltac2/example1.v
@@ -0,0 +1,27 @@
+Require Import Ltac2.Ltac2.
+
+Import Ltac2.Control.
+
+(** Alternative implementation of the hyp primitive *)
+Ltac2 get_hyp_by_name x :=
+  let h := hyps () in
+  let rec find x l := match l with
+  | [] => zero Not_found
+  | p :: l =>
+    match p with
+    | (id, _, t) =>
+      match Ident.equal x id with
+      | true => t
+      | false => find x l
+      end
+    end
+  end in
+  find x h.
+
+Print Ltac2 get_hyp_by_name.
+
+Goal forall n m, n + m = 0 -> n = 0.
+Proof.
+refine (fun () => '(fun n m H => _)).
+let t := get_hyp_by_name @H in Message.print (Message.of_constr t).
+Abort.