fetch a list of depends from _oasis file

gistfile1.ml

#use "topfind"
#require "oasis.base"

open OASISTypes
open OASISVersion

let (|>) x f = f x

let find_all_depends =
  let rec inner acc = function
    | [] -> acc
    | Library    (_, { bs_build_depends; _ }, _) :: sections
    | Executable (_, { bs_build_depends; _ }, _) :: sections ->
      let findlib_depends = List.fold_left
        (fun acc -> function
           | FindlibPackage (name, Some v) ->
             Printf.sprintf "%s(%s)" name (string_of_comparator v) :: acc
           | FindlibPackage (name, None) ->
             name :: acc
           | _ -> acc
        ) [] bs_build_depends
      in inner (acc @ findlib_depends) sections
    | _ :: sections -> inner acc sections
  in inner []

let is_library =
  List.exists (function Library _ -> true | _ -> false)

let is_executable =
  List.exists (function Executable _ -> true | _ -> false)

let () =
  let oasis_fn = Sys.argv.(1) in
  let { sections; _ } = OASISParse.from_file
      ~ctxt:{!BaseContext.default with OASISContext.ignore_plugins = true}
      oasis_fn
  in

  List.iter (fun name -> print_endline name) (find_all_depends sections);
  print_endline (if is_executable sections then "is executable" else "is not executable");
  print_endline (if is_library sections then "is library" else "is not library")