Re: [Caml-list] howto: recursively iterate over filesystem

["Daniel Bünzli" <daniel.buenzli@erratique.ch>]

Hello, 

The book on Unix system programming in OCaml shows how to write a `find` function. 

    http://ocamlunix.forge.ocamlcore.org/files.html#htoc11

But if you don't need tight control over the process and don't want to link against the Unix module, just roll your own with the functions in Sys. 

That's what I usually use (note that it does follow symlinks). 

    val fold_files_rec : string list -> ('a -> string -> 'a) -> 'a -> 'a
    (** [fold_files_rec dirs f acc] lists the files in [dirs], recursively
         in depth first order and folds the function [f] over the file names. *)

    let fold_files_rec dirs f acc = 
      let readdir d = try Array.to_list (Sys.readdir d) with Sys_error _ -> [] in
      let is_dir d = try Sys.is_directory d with Sys_error _ -> false in
      let rec loop f acc = function
      | (d :: ds) :: up -> 
         let files = List.rev (List.rev_map (Filename.concat d) (readdir d)) in
         let dirs, files = List.partition is_dir files in
         let acc = List.fold_left f acc files in 
         loop f acc (dirs :: ds :: up)
      | [] :: [] -> acc
      | [] :: up -> loop f acc up
      | _ -> assert false
      in
      loop f acc (dirs :: []) 

Best,

Daniel