From: Stefano Zacchiroli <zack@upsilon.cc>
Date: Tue, 11 Oct 2005 08:24:33 +0000 (+0000)
Subject: added list_concat
X-Git-Tag: V_0_7_2_3~223
X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=commitdiff_plain;h=ca6abc9a3c4e7b5ab614dfa097f87996a6383d68;p=helm.git

added list_concat
---

diff --git a/helm/ocaml/extlib/hExtlib.ml b/helm/ocaml/extlib/hExtlib.ml
index 31cf86a75..ceb9c8d8b 100644
--- a/helm/ocaml/extlib/hExtlib.ml
+++ b/helm/ocaml/extlib/hExtlib.ml
@@ -104,6 +104,15 @@ let rec filter_map f =
       | None -> filter_map f tl
       | Some v -> v :: filter_map f tl)
 
+let list_concat ?(sep = []) =
+  let rec aux acc =
+    function
+    | [] -> []
+    | [ last ] -> List.flatten (List.rev (last :: acc))
+    | hd :: tl -> aux ([sep; hd] @ acc) tl
+  in
+  aux []
+
 (** {2 File predicates} *)
 
 let is_dir fname =
diff --git a/helm/ocaml/extlib/hExtlib.mli b/helm/ocaml/extlib/hExtlib.mli
index 46ea0b9ce..e40920350 100644
--- a/helm/ocaml/extlib/hExtlib.mli
+++ b/helm/ocaml/extlib/hExtlib.mli
@@ -54,8 +54,9 @@ val trim_blanks: string -> string (** strip heading and trailing blanks *)
 
 (** {2 List processing} *)
 
-val list_uniq: 'a list -> 'a list (* uniq unix filter on lists *)
-val filter_map: ('a -> 'b option) -> 'a list -> 'b list (* filter + map *)
+val list_uniq: 'a list -> 'a list (** uniq unix filter on lists *)
+val filter_map: ('a -> 'b option) -> 'a list -> 'b list (** filter + map *)
+val list_concat: ?sep:'a list -> 'a list list -> 'a list (**String.concat-like*)
 
 (** {2 Debugging & Profiling} *)