Text.Playlist

Playlist Types

data Track

A single music file or streaming URL.

Constructors

Track

Fields

• trackURL :: Text

  URL for a file or streaming resource.

• trackTitle :: Maybe Text

  Optional title.

• trackDuration :: Maybe Float

  Optional duration in seconds.

Instances

Eq Track

Defined in Text.Playlist.Types

Methods

(==) :: Track -> Track -> Bool

(/=) :: Track -> Track -> Bool

Show Track

Defined in Text.Playlist.Types

Methods

showsPrec :: Int -> Track -> ShowS

show :: Track -> String

showList :: [Track] -> ShowS

type Playlist = [Track]

A list of Tracks.

Playlist Formats

data Format

Playlist formats.

Constructors

PLS

http://en.wikipedia.org/wiki/PLS_(file_format)

M3U

M3U and M3U8. http://en.wikipedia.org/wiki/M3U

Instances

Eq Format

Defined in Text.Playlist.Types

Methods

(==) :: Format -> Format -> Bool

(/=) :: Format -> Format -> Bool

Read Format

Defined in Text.Playlist.Types

Methods

readsPrec :: Int -> ReadS Format

readList :: ReadS [Format]

readPrec :: ReadPrec Format

readListPrec :: ReadPrec [Format]

Show Format

Defined in Text.Playlist.Types

Methods

showsPrec :: Int -> Format -> ShowS

show :: Format -> String

showList :: [Format] -> ShowS

Parsing and Generating

parsePlaylist :: Format -> ByteString -> Either String Playlist

Parse a playlist from a ByteString. Parsing may fail in which case an error message is returned in Left.

content <- BS.getContents
case parsePlaylist M3U content of
 Left err -> fail $ "failed to parse playlist: " ++ err
 Right x  -> return x

parserForFormat :: Format -> Parser Playlist

Return the appropriate attoparsec parser for the given playlist format.

generatePlaylist :: Format -> Playlist -> ByteString

Generate a lazy ByteString containing playlist data from the given playlist and in the given format.

BL.putStr $ generatePlaylist M3U somePlaylist

Utility Functions

fileNameToFormat :: FilePath -> Maybe Format

Try to figure out a file's format from it's file extension.

>>> fileNameToFormat "foo.m3u"
Just M3U

>>> fileNameToFormat "foo.M3U"
Just M3U

>>> fileNameToFormat "foo.txt"
Nothing

appendExtension :: Format -> FilePath -> FilePath

Given a file name that does not have a file extension, return a file name with the appropriate extension included based on the given format.

>>> appendExtension M3U "foo"
"foo.m3u"

resolve

Arguments

:: forall m. Monad m

=> Playlist

A Playlist that may contain references to other playlists.

-> (Text -> m Playlist)

Downloading function. This function should take a URL and return a parsed playlist.

It's expected that the URL points to another playlist that needs to be parsed and possibly resolved.

-> m Playlist

A fully resolved Playlist. (All tracks should be files and not links to other playlists.)

If the given Playlist contains tracks that reference remote playlists, this function will recursively download and process these playlists. Returns a flattened playlist that should not contain any references to other playlists.

You supply the downloading function as the second argument. Use whichever HTTP library that makes you happy.

There are two error conditions that are ignored by this function:

1. The nesting of playlists exceeds a (hard-coded) limit. In this case no playlists beyond the limit are processed. Open a pull request if you'd like to have a resolveN function that allows you to specific the depth limit or one that returns an error.
2. A downloaded playlist contains a syntax error. In this case the playlist is consider to have no tracks and is ignored. Open a pull request if you want a version of this function that returns some sort of an error instead of ignoring bad playlists.