RFC5646

A parser of RFC5646 in Haskell.

Features

• Lens-enabled
• instance of Read class
  • use readMaby

• instance of Eq class
  • case insensitive equality
• support for common convention formatting
• check if a tag is valid
• check if a tag is private

Basic usage :

   >>> read "de" :: LanguageTag
   Normal (Langtag {_language = ISO639 {_primary = "de", _extended = []}, _script = Nothing, _region = Nothing, _variant = [], _extension = [], _privateuse = []})
   

   >>> read "DE" :: LanguageTag
   Normal (Langtag {_language = ISO639 {_primary = "DE", _extended = []}, _script = Nothing, _region = Nothing, _variant = [], _extension = [], _privateuse = []})
   

Equality :

   >>> let l1 =read "de" :: LanguageTag
   
   >>> let l2 =read "DE" :: LanguageTag
   
   >>> l1 == l2
   True
   

Tag Access :

zh-Hant (Chinese written using the Traditional Chinese script)

   >>> let c1 = read "zh-Hant" :: LanguageTag
   
   >>> c1 ^. (_Normal . language . primary)
   "zh"
   
   >>> c1 ^. (_Normal . language . extended)
   []
   
   >>> c1 ^. (_Normal . script)
   Just "Hant"
   
   >>> c1 ^. (_Normal . region)
   Nothing
   
   >>> c1 ^. (_Normal . variant)
   []
   
   >>> c1 ^. (_Normal . extension)
   []
   
   >>> c1 ^. (_Normal . privateuse )
   []
   

zh-cmn-Hans-CN (Chinese, Mandarin, Simplified script, as used in China)

   >>> let c2 = read "zh-cmn-Hans-CN" :: LanguageTag
   
   >>> c2 ^. (_Normal . language . primary)
   "zh"
   
   >>> c2 ^. (_Normal . language . extended)
   ["cmn"]
   
   >>> c2 ^. (_Normal . script)
   Just "Hans"
   
   >>> c2 ^. (_Normal . region)
   Just "CN"
   
   >>> c2 ^. (_Normal . variant)
   []
   
   >>> c2 ^. (_Normal . extension)
   []
   
   >>> c2 ^. (_Normal . privateuse)
   []
   

sl-rozaj-biske (San Giorgio dialect of Resian dialect of Slovenian)

   >>> let c3 = read "sl-rozaj-biske" :: LanguageTag
   
   >>> c3 ^. (_Normal . language . primary)
   "sl"
   
   >>> c3 ^. (_Normal . language . extended)
   []
   
   >>> c3 ^. (_Normal . script)
   Nothing
   
   >>> c3 ^. (_Normal . region)
   Nothing
   
   >>> c3 ^. (_Normal . variant)
   ["rozaj","biske"]
   
   >>> c3 ^. (_Normal . extension)
   []
   
   >>> c3 ^. (_Normal . privateuse)
   []
   

az-Arab-x-AZE-derbend (Private use subtags)

   >>> let c4 = read "az-Arab-x-AZE-derbend" :: LanguageTag
   
   >>> c4
   Normal (Langtag {_language = ISO639 {_primary = "az", _extended = []}, _script = Just "Arab", _region = Nothing, _variant = [], _extension = [], _privateuse = ["x","AZE","derbend"]})
   
   >>> c4 ^. (_Normal . language . primary)
   "az"
   
   >>> c4 ^. (_Normal . language . extended)
   []
   
   >>> c4 ^. (_Normal . script)
   Just "Arab"
   
   >>> c4 ^. (_Normal . region)
   Nothing
   
   >>> c4 ^. (_Normal . variant)
   []
   
   >>> c4 ^. (_Normal . extension)
   []
   
   >>> c4 ^. (_Normal . privateuse)
   ["x","AZE","derbend"]
   

Privateness :

qaa-Qaaa-QM-x-southern (all private tags)

   >>> let c5 = read "qaa-Qaaa-QM-x-southern" :: LanguageTag
   
   >>> c5 & previews _Normal isPrivateOfPrimaryLanguageSubtag
   Just True
   
   >>> c5 & previews _Normal isPrivateOfScript
   Just True
   
   >>> c5 & previews _Normal isPrivateOfPrimaryLanguageSubtag
   Just True
   

Shortcut :

When you know that you don't use a grandfathered tag nor a private tag at the beginning, use Langtag type insted of LanguageTag.

   >>> let c2' = read "zh-cmn-Hans-CN" :: Langtag
   
   >>> c2'
   Langtag {_language = ISO639 {_primary = "zh", _extended = ["cmn"]}, _script = Just "Hans", _region = Just "CN", _variant = [], _extension = [], _privateuse = []}
   
   >>> c2' ^. (language . primary)
   "zh"
   
   >>> c2' ^. (language . extended)
   ["cmn"]
   
   >>> c2' ^. script
   Just "Hans"
   
   >>> c2' ^. region
   Just "CN"
   

Safety :

The read function is not safe, so use readMaybe

   >>> import Text.Read
   
   >>> readMaybe "qaa-Qaaa-QM-x-southern" :: Maybe LanguageTag
   Just (Normal (Langtag {_language = ISO639 {_primary = "qaa", _extended = []}, _script = Just "Qaaa", _region = Just "QM", _variant = [], _extension = [], _privateuse = ["x","southern"]}))
   

   >>> readMaybe "abcdefg" :: Maybe LanguageTag
   Nothing
   

Validity :

   >>> eitherValid "a-b-c"
   Left "parse error : a-b-c"
   

duplication check

   >>> isValid $ read "xxx-xxxxx"
   True
   
   >>> isValid $ read "xxx-xxxxx-xxxxx"
   False
   

   >>> isValid $ read "xxx-a-xxxxx-b-xxxxx"
   True
   
   >>> isValid $ read "xxx-a-xxxxx-a-xxxxx"
   False