(.module:
  [library
   [lux {"-" [Name]}
    [abstract
     [equivalence {"+" [Equivalence]}]
     [monoid {"+" [Monoid]}]
     ["[0]" monad {"+" [do]}]]
    [control
     ["[0]" try {"+" [Try]}]
     ["[0]" exception {"+" [exception:]}]]
    [data
     ["[0]" text
      ["%" format {"+" [format]}]]
     [collection
      ["[0]" dictionary {"+" [Dictionary]}]
      ["[0]" set {"+" [Set]}]
      ["[0]" list ("[1]\[0]" mix)]]]]]
  ["[0]" // "_"
   ["[1]" profile {"+" [Name Profile]}]])

(def: .public file
  "project.lux")

(type: .public Project
  (Dictionary Name Profile))

(def: .public (project name profile)
  (-> Name Profile Project)
  (dictionary.of_list text.hash (list [name profile])))

(def: .public equivalence
  (Equivalence Project)
  (dictionary.equivalence //.equivalence))

(implementation: .public monoid
  (Monoid Project)

  (def: identity
    (dictionary.empty text.hash))

  (def: composite
    (dictionary.merged_with (\ //.monoid composite))))

(exception: .public (unknown_profile [name Name])
  (exception.report
   ["Name" (%.text name)]))

(exception: .public (circular_dependency [dependee Name
                                          dependent Name])
  (exception.report
   ["Dependent" (%.text dependent)]
   ["Dependee" (%.text dependee)]))

(def: (profile' lineage project name)
  (-> (Set Name) Project Name (Try Profile))
  (case (dictionary.value name project)
    {#.Some profile}
    (case (list.example (set.member? lineage)
                        (value@ #//.parents profile))
      {#.Some ouroboros}
      (exception.except ..circular_dependency [ouroboros name])
      
      #.None
      (do [! try.monad]
        [parents (monad.each ! (profile' (set.has name lineage) project)
                             (value@ #//.parents profile))]
        (in (list\mix (function (_ parent child)
                        (\ //.monoid composite child parent))
                      (with@ #//.parents (list) profile)
                      parents))))
    
    #.None
    (exception.except ..unknown_profile [name])))

(def: .public profile
  (-> Project Name (Try Profile))
  (..profile' (set.empty text.hash)))