Truth isn’t Truth

#! /usr/bin/haskell
import Data.List
statementList :: [String]
statementList =
  ["Truth isn’t truth."
  ["Truth isn’t truth."
  ["Truth isn’t truth."
  ,"1+1=2."
  ,"Even Carroll doesn’t know the solution of his riddle."
  ,"Even Carroll doesn’t know the solution of his riddle."
  ,"Even Carroll doesn’t know the solution of his riddle."
  ]
atLeastThrice :: [String] -> [String]
atLeastThrice sL =
  [head grp | grp <-
    group $ sort sL, length grp >= 3]

Result (if loaded and executed in GHCi):

*Main> atLeastThrice statementList
["Even Carroll doesn’t know the solution of his riddle.","Truth isn’t truth."]