Data.Ascii now uses convertible

[time-http.git] / Data / Time / Asctime.hs

diff --git a/Data/Time/Asctime.hs b/Data/Time/Asctime.hs
index 39d9961a8f68b0cd2c62641c464e964d13a02d8d..f7d7bddaa64114ad20728428119d6d38b6ae2e49 100644 (file)
--- a/Data/Time/Asctime.hs
+++ b/Data/Time/Asctime.hs
@@ -1,5 +1,7 @@
 {-# LANGUAGE
-    OverloadedStrings
+    FlexibleInstances
+  , MultiParamTypeClasses
+  , OverloadedStrings
   , UnicodeSyntax
   #-}
 -- |This module provides functions for ANSI C's asctime() format.
@@ -23,36 +25,45 @@
 -- As you can see, it has no time zone info. "Data.Time.HTTP" will
 -- treat it as UTC.
 module Data.Time.Asctime
-    ( -- * Formatting
-      toAscii
-    , toAsciiBuilder
-
-      -- * Parsing
-    , fromAscii
+    ( Asctime
     , asctime
     )
     where
+import Control.Applicative
 import Data.Ascii (Ascii, AsciiBuilder)
 import qualified Data.Ascii as A
 import Data.Attoparsec.Char8
+import Data.Convertible.Base
 import Data.Monoid.Unicode
+import Data.Tagged
 import Data.Time
 import Data.Time.Calendar.WeekDate
 import Data.Time.HTTP.Common
 import Prelude.Unicode
 
--- |Convert a 'LocalTime' to ANSI C's @asctime()@ string.
-toAscii ∷ LocalTime → Ascii
-toAscii = A.fromAsciiBuilder ∘ toAsciiBuilder
+-- |The phantom type for conversion between ANSI C's @asctime()@
+-- string and 'LocalTime'.
+data Asctime
 
--- |Parse an ANSI C's @asctime()@ string. When the string can't be
--- parsed, it returns @'Left' err@.
-fromAscii ∷ Ascii → Either String LocalTime
-fromAscii = parseOnly p ∘ A.toByteString
-    where
-      p = do zt ← asctime
-             endOfInput
-             return zt
+instance ConvertSuccess LocalTime (Tagged Asctime Ascii) where
+    {-# INLINE convertSuccess #-}
+    convertSuccess = (A.fromAsciiBuilder <$>) ∘ cs
+
+instance ConvertAttempt LocalTime (Tagged Asctime Ascii) where
+    {-# INLINE convertAttempt #-}
+    convertAttempt = return ∘ cs
+
+instance ConvertSuccess LocalTime (Tagged Asctime AsciiBuilder) where
+    {-# INLINE convertSuccess #-}
+    convertSuccess = Tagged ∘ toAsciiBuilder
+
+instance ConvertAttempt LocalTime (Tagged Asctime AsciiBuilder) where
+    {-# INLINE convertAttempt #-}
+    convertAttempt = return ∘ cs
+
+instance ConvertAttempt (Tagged Asctime Ascii) LocalTime where
+    {-# INLINE convertAttempt #-}
+    convertAttempt = parseAttempt' asctime ∘ untag
 
 -- |Parse an ANSI C's @asctime()@ string.
 asctime ∷ Parser LocalTime
@@ -76,7 +87,6 @@ asctime = do weekDay ← shortWeekDayNameP
 
              return (LocalTime gregDay tod)
 
--- |Convert a 'LocalTime' to ANSI C's @asctime()@ string.
 toAsciiBuilder ∷ LocalTime → AsciiBuilder
 toAsciiBuilder localTime
     = let (year, month, day) = toGregorian (localDay localTime)