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