(.module:
  [library
   [lux {"-" [Module]}
    [abstract
     ["[0]" monad {"+" [Monad do]}]]
    [control
     ["[0]" try {"+" [Try]}]
     ["[0]" exception {"+" [exception:]}]
     [concurrency
      ["[0]" async {"+" [Async]} ("[1]\[0]" monad)]]
     ["<>" parser
      ["<[0]>" binary]]]
    [data
     [binary {"+" [Binary]}]
     ["[0]" text
      ["%" format {"+" [format]}]]
     [collection
      ["[0]" dictionary {"+" [Dictionary]}]
      ["[0]" row]]
     [format
      ["[0]" tar]]]
    [tool
     [compiler
      [meta
       [archive
        [descriptor {"+" [Module]}]]]]]
    [world
     ["[0]" file]]]]
  [//
   [cli {"+" [Library]}]])

(def: Action
  (type (All (_ a) (Async (Try a)))))

(exception: .public useless_tar_entry)

(exception: .public (duplicate [library Library
                                module Module])
  (exception.report
   ["Module" (%.text module)]
   ["Library" (%.text library)]))

(type: .public Import
  (Dictionary file.Path Binary))

(def: (import_library system library import)
  (-> (file.System Async) Library Import (Action Import))
  (let [! async.monad]
    (|> library
        (\ system read)
        (\ ! each (let [! try.monad]
                    (|>> (\ ! each (<binary>.result tar.parser))
                         (\ ! conjoint)
                         (\ ! each (|>> row.list
                                        (monad.mix ! (function (_ entry import)
                                                       (case entry
                                                         (#tar.Normal [path instant mode ownership content])
                                                         (let [path (tar.from_path path)]
                                                           (case (dictionary.has' path (tar.data content) import)
                                                             (#try.Failure error)
                                                             (exception.except ..duplicate [library path])

                                                             import'
                                                             import'))
                                                         
                                                         _
                                                         (exception.except ..useless_tar_entry [])))
                                                   import)))
                         (\ ! conjoint)))))))

(def: .public (import system libraries)
  (-> (file.System Async) (List Library) (Action Import))
  (monad.mix (: (Monad Action)
                (try.with async.monad))
             (..import_library system)
             (dictionary.empty text.hash)
             libraries))