Stdlib functional iterators (#1002)

* add `Seq` module, expose iterator conversions in most containers

* small typo

* typo

* change order of arguments for `{Map,Set}.add_seq`

* watch for max string length in `Bytes.of_seq`

* wip: make it build again

* Fix dependency

Sys needs to be linked before Bytes in stdlib.

* Update threads/stdlib.ml

* Update stdlib_no_prefixed/.depend

* fix inconsistencies with label modules

* update testsuite to work with seq

* update change file

* small change in `Hashtbl.to_seq`, capturing only the underlying array

* add some documentation to seq.mli

* revert to good ol' module type names for hashtables

* fix test

* change style of comments in seq.mli

* follow some demands in review of GPR #1002

* some fixes for #1002

* add Seq-related functions to Ephemeron

* add some comments on `Hashtbl.of_seq`

* add more tests for `Hashtbl.{to,of}_seq`

* fix bug in `Ephemeron.to_seq`

* Update Changes

1 files changed, 17 insertions, 0 deletions

diff --git a/stdlib/map.mli b/stdlib/map.mli
index 7552c480a5..531fb8fe6c 100644
--- a/stdlib/map.mli
+++ b/stdlib/map.mli
@@ -306,7 +306,24 @@ module type S =
     (** Same as {!Map.S.map}, but the function receives as arguments both the
        key and the associated value for each binding of the map. *)
 
+    (** {6 Iterators} *)
 
+    val to_seq : 'a t -> (key * 'a) Seq.t
+    (** Iterate on the whole map, in ascending order
+        @since 4.07 *)
+
+    val to_seq_from : key -> 'a t -> (key * 'a) Seq.t
+    (** [to_seq_from k m] iterates on a subset of the bindings of [m],
+        in ascending order, from key [k] or above.
+        @since 4.07 *)
+
+    val add_seq : (key * 'a) Seq.t -> 'a t -> 'a t
+    (** Add the given bindings to the map, in order.
+        @since 4.07 *)
+
+    val of_seq : (key * 'a) Seq.t -> 'a t
+    (** Build a map from the given bindings
+        @since 4.07 *)
   end
 (** Output signature of the functor {!Map.Make}. *)