Safe Haskell	Safe-Inferred
Language	GHC2021

Streamly.FSNotify

Description

Example

Here is a program which watches /home/georgefst/c-project and any of its subdirectories for added or modified C source files (which we take to be anything with a .c extension). This program then writes that the event occurred, to what file, and when, forever.


import Data.Functor.Contravariant (Predicate (Predicate))
import Streamly.Data.Fold qualified as SF
import Streamly.Data.Stream.Prelude qualified as SP
import System.FilePath (isExtensionOf, (</>))

import Streamly.FSNotify

isCSourceFile :: Predicate Event
isCSourceFile = Predicate \e ->
    "c" `isExtensionOf` eventPath e && eventIsDirectory e == IsFile

notDeletion :: Predicate Event
notDeletion = Predicate \case
    Removed{} -> False
    _ -> True

srcPath :: FilePath
srcPath = "/" </> "home" </> "gthomas" </> "c-project"

main :: IO ()
main = SP.fold (SF.drainMapM go) $ watchTree srcPath $ isCSourceFile <> notDeletion
  where
    go = \case
        Added p t _ -> putStrLn $ "Created: " ++ show p ++ " at " ++ show t
        Modified p t _ -> putStrLn $ "Modified: " ++ show p ++ " at " ++ show t
        _ -> pure ()

Synopsis

data Event
- = Added {
  - eventPath :: FilePath
  - eventTime :: UTCTime
  - eventIsDirectory :: EventIsDirectory
  }
- | Modified {
  - eventPath :: FilePath
  - eventTime :: UTCTime
  - eventIsDirectory :: EventIsDirectory
  }
- | ModifiedAttributes {
  - eventPath :: FilePath
  - eventTime :: UTCTime
  - eventIsDirectory :: EventIsDirectory
  }
- | Removed {
  - eventPath :: FilePath
  - eventTime :: UTCTime
  - eventIsDirectory :: EventIsDirectory
  }
- | WatchedDirectoryRemoved {
  - eventPath :: FilePath
  - eventTime :: UTCTime
  - eventIsDirectory :: EventIsDirectory
  }
- | CloseWrite {
  - eventPath :: FilePath
  - eventTime :: UTCTime
  - eventIsDirectory :: EventIsDirectory
  }
- | Unknown {
  - eventPath :: FilePath
  - eventTime :: UTCTime
  - eventIsDirectory :: EventIsDirectory
  - eventString :: String
  }
data EventIsDirectory
- = IsFile
- | IsDirectory
watchDir :: (MonadAsync m, MonadCatch m) => FilePath -> Predicate Event -> Stream m Event
watchTree :: (MonadAsync m, MonadCatch m) => FilePath -> Predicate Event -> Stream m Event

Documentation

data Event #

A file event reported by a file watcher. Each event contains the canonical path for the file and a timestamp guaranteed to be after the event occurred (timestamps represent current time when FSEvents receives it from the OS and/or platform-specific Haskell modules).

Constructors

Added
Fields eventPath :: FilePath eventTime :: UTCTime eventIsDirectory :: EventIsDirectory
Modified
Fields eventPath :: FilePath eventTime :: UTCTime eventIsDirectory :: EventIsDirectory
ModifiedAttributes
Fields eventPath :: FilePath eventTime :: UTCTime eventIsDirectory :: EventIsDirectory
Removed
Fields eventPath :: FilePath eventTime :: UTCTime eventIsDirectory :: EventIsDirectory
WatchedDirectoryRemoved	Note: Linux-only
Fields eventPath :: FilePath eventTime :: UTCTime eventIsDirectory :: EventIsDirectory
CloseWrite	Note: Linux-only
Fields eventPath :: FilePath eventTime :: UTCTime eventIsDirectory :: EventIsDirectory
Unknown	Note: Linux-only
Fields eventPath :: FilePath eventTime :: UTCTime eventIsDirectory :: EventIsDirectory eventString :: String

Instances

Instances details

Show Event
Instance details Defined in System.FSNotify.Types Methods showsPrec :: Int -> Event -> ShowS # show :: Event -> String # showList :: [Event] -> ShowS #
Eq Event
Instance details Defined in System.FSNotify.Types Methods (==) :: Event -> Event -> Bool # (/=) :: Event -> Event -> Bool #

data EventIsDirectory #

Constructors

IsFile
IsDirectory

Instances

Instances details

Show EventIsDirectory
Instance details Defined in System.FSNotify.Types Methods showsPrec :: Int -> EventIsDirectory -> ShowS # show :: EventIsDirectory -> String # showList :: [EventIsDirectory] -> ShowS #
Eq EventIsDirectory
Instance details Defined in System.FSNotify.Types Methods (==) :: EventIsDirectory -> EventIsDirectory -> Bool # (/=) :: EventIsDirectory -> EventIsDirectory -> Bool #

watchDir :: (MonadAsync m, MonadCatch m) => FilePath -> Predicate Event -> Stream m Event Source #

Watch a given directory, but only at one level (thus, subdirectories will not be watched recursively).

watchTree :: (MonadAsync m, MonadCatch m) => FilePath -> Predicate Event -> Stream m Event Source #

Watch a given directory recursively (thus, subdirectories will also have their contents watched).