PhoneBook.purs

module Data.PhoneBook where

import Data.List
import Data.Maybe

import Control.Plus (empty)


type Entry = { firstName :: String, lastName :: String, phone :: String }
type PhoneBook = List Entry


showEntry :: Entry -> String
showEntry entry = entry.lastName ++ ", " ++
                  entry.firstName ++ ": " ++
                  entry.phone


emptyBook :: PhoneBook
emptyBook = empty

insertEntry :: Entry -> PhoneBook -> PhoneBook
insertEntry = Cons


findEntry :: String -> String -> PhoneBook -> Maybe Entry
findEntry firstName lastName = filter filterEntry >>> head
    where
      filterEntry :: Entry -> Boolean
      filterEntry entry = entry.firstName == firstName && entry.lastName == lastName

-- examples
exampleEntry = { firstName: "John", lastName: "Smith", phone: "555-555-5555" }
exampleBook = insertEntry exampleEntry emptyBook

printEntry firstName lastName book = showEntry <$> findEntry firstName lastName book

book3 = insertEntry {firstName: "chris", lastName: "mcd", phone: "999"} exampleBook