Nixのprofileを5件残して後は14日過ぎてたら掃除するやつ

pgc.hs

import Data.Function ((&))
import Data.Functor ((<&>))
import Data.List
import Foreign.C.Types
import System.Directory (getDirectoryContents, removeFile)
import qualified System.Posix.Files as F
import System.Posix.Time

main = do
  let root = "/nix/var/nix/profiles/"
  paths <- getDirectoryContents root
  let oldpaths = paths & filter (isPrefixOf "system-") & sortBy (flip compare) & drop 5
  oldpaths' <- oldpaths & map (\n -> let p = root ++ n in (F.getSymbolicLinkStatus p <&> \s -> (p, (F.modificationTime s)))) & sequence
  ago14 <- epochTime <&> \now -> now - 14 * 24 * 60 * 60
  let targets = oldpaths' & filter (\(_, m) -> m < ago14) & map (\(p, _) -> p)
  mapM_ (\p -> removeFile p >>= \_ -> putStrLn p) targets