elm/exercises/grade-school/GradeSchool.example

module GradeSchool exposing (..)

import Dict exposing (..)


type alias Grade =
  Int


type alias Student =
  String


type alias School =
  Dict Int (List Student)


empty : School
empty =
  Dict.empty


addStudent : Grade -> Student -> School -> School
addStudent grade student school =
  Dict.insert grade (List.sort (student :: (studentsInGrade grade school))) school


studentsInGrade : Grade -> School -> List Student
studentsInGrade grade school =
  case (Dict.get grade school) of
    Just list ->
      list

    Nothing ->
      []


allStudents : School -> List ( Grade, List Student )
allStudents school =
  Dict.toList school |> List.sortBy fst