Haskell implementation of a addressbook

addressbook

import Text.CSV

type FirstName = String
type LastName = String
type MiddleName = String
type FullName = String
type PhoneNumber = String

data Contact =  Contact 
    { firstname :: FirstName
    , middlename :: MiddleName
    , lastname :: LastName
    , fullname :: FullName
    , phonenumber :: PhoneNumber } deriving (Show, Eq)

type AdressBook = [Contact]

changePhone :: Contact -> PhoneNumber -> Contact
changePhone contact p = Contact fin mn  ln fn p
    where
        fin = firstname contact
        mn = middlename contact
        ln = lastname contact
        fn = fullname contact

addContact :: AdressBook -> Contact -> AdressBook
addContact book con = con:book

isContact :: Contact -> Contact -> Bool
isContact con econ = con == econ

removeContact :: AdressBook -> Contact -> AdressBook
removeContact book con = filter (\x -> not (isContact con x)) book

getContact :: AdressBook -> Contact -> Contact
getContact book con = head list
    where
        list = filter (\x  -> isContact con x) book

nrOfContacts :: AdressBook -> Int
nrOfContacts book = length book

loadAddressBook :: String -> AdressBook
loadAddressBook path = do
    csvFile <- parseCSVFromFile path 
    return (map createContact (fromCSV csvFile))

fromCSV (Left parseError) = error (show parseError)
fromCSV (Right rows) = rows

createContact [ln,mdn,fn,gsm] =
  Contact ln mdn fn gsm