[lib] Split auxiliary libraries into Coq-specific and general.

Up to this point the `lib` directory contained two different library
archives, `clib.cma` and `lib.cma`, which a rough splitting between
Coq-specific libraries and general-purpose ones.

We know split the directory in two, as to make the distinction clear:

- `clib`: contains libraries that are not Coq specific and implement
  common data structures and programming patterns. These libraries
  could be eventually replace with external dependencies and the rest
  of the code base wouldn't notice much.

- `lib`: contains Coq-specific common libraries in widespread use
  along the codebase, but that are not considered part of other
  components. Examples are printing, error handling, or flags.

In some cases we have coupling due to utility files depending on Coq
specific flags, however this commit doesn't modify any files, but only
moves them around, further cleanup is welcome, as indeed a few files
in `lib` should likely be placed in `clib`.

Also note that `Deque` is not used ATM.

1 files changed, 58 insertions, 0 deletions

diff --git a/clib/deque.mli b/clib/deque.mli
new file mode 100644
index 000000000..23cb1e491
--- /dev/null
+++ b/clib/deque.mli
@@ -0,0 +1,58 @@
+(************************************************************************)
+(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
+(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2017     *)
+(*   \VV/  **************************************************************)
+(*    //   *      This file is distributed under the terms of the       *)
+(*         *       GNU Lesser General Public License Version 2.1        *)
+(************************************************************************)
+
+(** * Purely functional, double-ended queues *)
+
+(** This module implements the banker's deque, from Okasaki. Most operations are
+    amortized O(1). *)
+
+type +'a t
+
+exception Empty
+
+(** {5 Constructor} *)
+
+val empty : 'a t
+
+(** The empty deque. *)
+
+(** {5 Left-side operations} *)
+
+val lcons : 'a -> 'a t -> 'a t
+(** Pushes an element on the left side of the deque. *)
+
+val lhd : 'a t -> 'a
+(** Returns the leftmost element in the deque. Raises [Empty] when empty. *)
+
+val ltl : 'a t -> 'a t
+(** Returns the left-tail of the deque. Raises [Empty] when empty. *)
+
+(** {5 Right-side operations} *)
+
+val rcons : 'a -> 'a t -> 'a t
+(** Same as [lcons] but on the right side. *)
+
+val rhd : 'a t -> 'a
+(** Same as [lhd] but on the right side. *)
+
+val rtl : 'a t -> 'a t
+(** Same as [ltl] but on the right side. *)
+
+(** {5 Operations} *)
+
+val rev : 'a t -> 'a t
+(** Reverse deque. *)
+
+val length : 'a t -> int
+(** Length of a deque. *)
+
+val is_empty : 'a t -> bool
+(** Emptyness of a deque. *)
+
+val filter : ('a -> bool) -> 'a t -> 'a t
+(** Filters the deque *)