diff --git a/Data/Dates.hs b/Data/Dates.hs
--- a/Data/Dates.hs
+++ b/Data/Dates.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE UnicodeSyntax, DeriveDataTypeable #-}
+{-# LANGUAGE UnicodeSyntax, DeriveDataTypeable, FlexibleContexts #-}
 -- | Operations with dates
 module Data.Dates
   (DateTime (..),
@@ -30,7 +30,6 @@
 import Data.Time.Calendar.WeekDate
 import Data.Time.LocalTime
 import Text.Parsec
-import Text.Parsec.String
 import Data.Generics
 import Data.Char (toLower)
 
@@ -121,7 +120,7 @@
                  minute = tMinute t + minute dt,
                  second = tSecond t + second dt }
 
-euroNumDate ∷ Parsec String st DateTime
+euroNumDate ∷ Stream s m Char => ParsecT s st m DateTime
 euroNumDate = do
   d ← pDay
   char '.'
@@ -130,7 +129,7 @@
   y ← pYear
   return $ date y m d
 
-americanDate ∷ Parsec String st DateTime
+americanDate ∷ Stream s m Char => ParsecT s st m DateTime
 americanDate = do
   y ← pYear
   char '/'
@@ -139,21 +138,21 @@
   d ← pDay
   return $ date y m d
 
-euroNumDate' ∷ Int → Parsec String st DateTime
+euroNumDate' ∷ Stream s m Char => Int → ParsecT s st m DateTime
 euroNumDate' year = do
   d ← pDay
   char '.'
   m ← pMonth
   return $ date year m d
 
-americanDate' ∷ Int → Parsec String st DateTime
+americanDate' ∷ Stream s m Char => Int → ParsecT s st m DateTime
 americanDate' year = do
   m ← pMonth
   char '/'
   d ← pDay
   return $ date year m d
 
-strDate ∷ Parsec String st DateTime
+strDate ∷ Stream s m Char => ParsecT s st m DateTime
 strDate = do
   d ← pDay
   space
@@ -166,7 +165,7 @@
       notFollowedBy $ char ':'
       return $ date y m d
 
-strDate' ∷ Int → Parsec String st DateTime
+strDate' ∷ Stream s m Char => Int → ParsecT s st m DateTime
 strDate' year = do
   d ← pDay
   space
@@ -175,7 +174,7 @@
     Nothing → fail $ "unknown month: "++ms
     Just m  → return $ date year m d
 
-time24 ∷ Parsec String st Time
+time24 ∷ Stream s m Char => ParsecT s st m Time
 time24 = do
   h ← number 2 23
   char ':'
@@ -188,7 +187,7 @@
       notFollowedBy letter
       return $ Time h m s
 
-ampm ∷ Parsec String st Int
+ampm ∷ Stream s m Char => ParsecT s st m Int
 ampm = do
   s ← many1 letter
   case map toUpper s of
@@ -196,7 +195,7 @@
     "PM" → return 12
     _ → fail "AM/PM expected"
 
-time12 ∷ Parsec String st Time
+time12 ∷ Stream s m Char => ParsecT s st m Time
 time12 = do
   h ← number 2 12
   char ':'
@@ -209,10 +208,10 @@
   hd ← ampm
   return $ Time (h+hd) m s
 
-pTime ∷ Parsec String st Time
+pTime ∷ Stream s m Char => ParsecT s st m Time
 pTime = choice $ map try [time12, time24]
 
-pAbsDateTime ∷ Int → Parsec String st DateTime
+pAbsDateTime ∷ Stream s m Char => Int → ParsecT s st m DateTime
 pAbsDateTime year = do
   date ← choice $ map try $ map ($ year) $ [
                               const euroNumDate,
@@ -229,7 +228,7 @@
       t ← pTime
       return $ date `addTime` t
 
-pAbsDate ∷ Int → Parsec String st DateTime
+pAbsDate ∷ Stream s m Char => Int → ParsecT s st m DateTime
 pAbsDate year =
   choice $ map try $ map ($ year) $ [
                           const euroNumDate,
@@ -251,7 +250,11 @@
 
 -- | Modify DateTime with pure function on Day
 modifyDate ∷  (t → Day → Day) → t → DateTime → DateTime
-modifyDate fn x dt = dayToDateTime $ fn x $ dateTimeToDay dt
+modifyDate fn x dt =
+  let date = dayToDateTime $ fn x $ dateTimeToDay dt
+  in  date {hour   = hour   dt,
+            minute = minute dt,
+            second = second dt}
 
 -- | Add date interval to DateTime
 addInterval ∷  DateTime → DateInterval → DateTime
@@ -277,13 +280,13 @@
   abs $ toModifiedJulianDay (dateTimeToDay d1) -
         toModifiedJulianDay (dateTimeToDay d2)
 
-maybePlural ∷ String → Parsec String st String
+maybePlural ∷ Stream s m Char => String → ParsecT s st m String
 maybePlural str = do
   r ← string str
   optional $ char 's'
   return (capitalize r)
 
-pDateIntervalType ∷ Parsec String st DateIntervalType
+pDateIntervalType ∷ Stream s m Char => ParsecT s st m DateIntervalType
 pDateIntervalType = do
   s ← choice $ map maybePlural ["day", "week", "month", "year"]
   case toLower (head s) of
@@ -293,7 +296,7 @@
     'y' → return Year
     _ → fail $ "Unknown date interval type: " ++ s
 
-pDateInterval ∷ Parsec String st DateInterval
+pDateInterval ∷ Stream s m Char => ParsecT s st m DateInterval
 pDateInterval = do
   n ← many1 digit
   spaces
@@ -304,7 +307,7 @@
     Month → Months `fmap` tryReadInt n
     Year →  Years  `fmap` tryReadInt n
 
-pRelDate ∷ DateTime → Parsec String st DateTime
+pRelDate ∷ Stream s m Char => DateTime → ParsecT s st m DateTime
 pRelDate date = do
   offs ← try futureDate
      <|> try passDate
@@ -313,7 +316,7 @@
      <|> yesterday
   return $ date `addInterval` offs
 
-lastDate ∷ DateTime → Parsec String st DateTime
+lastDate ∷ Stream s m Char => DateTime → ParsecT s st m DateTime
 lastDate now = do
     string "last"
     spaces
@@ -335,7 +338,7 @@
       string "year"
       return $ now {month = 1, day = 1}
 
-nextDate ∷ DateTime → Parsec String st DateTime
+nextDate ∷ Stream s m Char => DateTime → ParsecT s st m DateTime
 nextDate now = do
     string "next"
     spaces
@@ -357,7 +360,7 @@
       string "year"
       return (now `addInterval` Years 1) {month = 1, day = 1}
 
-pWeekDay ∷ Parsec String st WeekDay
+pWeekDay ∷ Stream s m Char => ParsecT s st m WeekDay
 pWeekDay = do
   w ← many1 (oneOf "mondaytueswnhrfi")
   case map toLower w of
@@ -370,7 +373,7 @@
     "sunday"    → return Sunday
     _           → fail $ "Unknown weekday: " ++ w
 
-futureDate ∷ Parsec String st DateInterval
+futureDate ∷ Stream s m Char => ParsecT s st m DateInterval
 futureDate = do
   string "in "
   n ← many1 digit
@@ -382,7 +385,7 @@
     Month → Months `fmap` tryReadInt n
     Year →  Years  `fmap` tryReadInt n
 
-passDate ∷ Parsec String st DateInterval
+passDate ∷ Stream s m Char => ParsecT s st m DateInterval
 passDate = do
   n ← many1 digit
   char ' '
@@ -394,36 +397,36 @@
     Month → (Months . negate) `fmap` tryReadInt n
     Year →  (Years  . negate) `fmap` tryReadInt n
 
-today ∷ Parsec String st DateInterval
+today ∷ Stream s m Char => ParsecT s st m DateInterval
 today = do
   string "today" <|> string "now"
   return $ Days 0
 
-tomorrow ∷ Parsec String st DateInterval
+tomorrow ∷ Stream s m Char => ParsecT s st m DateInterval
 tomorrow = do
   string "tomorrow"
   return $ Days 1
 
-yesterday ∷ Parsec String st DateInterval
+yesterday ∷ Stream s m Char => ParsecT s st m DateInterval
 yesterday = do
   string "yesterday"
   return $ Days (-1)
 
-pByWeek ∷ DateTime → Parsec String st DateTime
+pByWeek ∷ Stream s m Char => DateTime → ParsecT s st m DateTime
 pByWeek date =
   try (lastDate date) <|> nextDate date
 
 -- | Parsec parser for DateTime.
-pDateTime ∷ DateTime       -- ^ Current date / time, to use as base for relative dates
-          → Parsec String st DateTime
+pDateTime ∷ Stream s m Char => DateTime       -- ^ Current date / time, to use as base for relative dates
+          → ParsecT s st m DateTime
 pDateTime date =
       (try $ pRelDate date)
   <|> (try $ pByWeek date)
   <|> (try $ pAbsDateTime $ year date)
 
 -- | Parsec parser for Date only.
-pDate ∷ DateTime       -- ^ Current date / time, to use as base for relative dates
-          → Parsec String st DateTime
+pDate ∷ Stream s m Char => DateTime       -- ^ Current date / time, to use as base for relative dates
+          → ParsecT s st m DateTime
 pDate date =
       (try $ pRelDate date)
   <|> (try $ pByWeek date)
diff --git a/Data/Dates/Formats.hs b/Data/Dates/Formats.hs
--- a/Data/Dates/Formats.hs
+++ b/Data/Dates/Formats.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE UnicodeSyntax, DeriveDataTypeable #-}
+{-# LANGUAGE UnicodeSyntax, DeriveDataTypeable, FlexibleContexts, FlexibleInstances #-}
 -- | This module allows to parse arbitrary date formats.
 -- Date formats are specified as strings:
 --
@@ -8,11 +8,14 @@
 --
 --  * "DD\/MM\/YYYY, HH:mm:SS"
 --
+--  * "YY.MM.DD[, HH:mm:SS]"
+--
 --  * and so on.
 --
 module Data.Dates.Formats
   (FormatElement (..), Format,
-   pFormat, formatParser,
+   FormatParser,
+   parseFormat, pFormat, formatParser,
    parseDateFormat
   ) where
 
@@ -25,86 +28,118 @@
 
 -- | Date\/time format element
 data FormatElement =
-    YEAR   Int
-  | MONTH  Int
-  | DAY    Int
-  | HOUR   Int
-  | MINUTE Int
-  | SECOND Int
-  | Fixed String
+    YEAR   Bool Int
+  | MONTH  Bool Int
+  | DAY    Bool Int
+  | HOUR   Bool Int
+  | MINUTE Bool Int
+  | SECOND Bool Int
+  | Whitespace Bool
+  | Fixed  Bool String
   deriving (Eq, Show)
 
+type FormatParser a = Parsec String Bool a
+
 -- | Date\/time format
 type Format = [FormatElement]
 
-nchars ∷ Char → Parsec String st Int
+nchars ∷ Char → FormatParser Int
 nchars c = do
   s ← many1 $ char c
   return $ length s
 
--- | Parser for date\/time format.
-pFormat ∷ Parsec String st Format
-pFormat = many1 $ choice $ map try [pYear, pMonth, pDay,
-                                    pHour, pMinute, pSecond,
-                                    pFixed]
+brackets :: FormatParser a -> FormatParser a
+brackets p = do
+  char '['
+  setState False
+  result <- p
+  char ']'
+  setState True
+  return result
+
+pFormat :: FormatParser Format
+pFormat = do
+    elems <- many1 $ try (brackets format) <|> format
+    return $ concat elems
+
   where
-    pYear   = YEAR   <$> nchars 'Y'
-    pMonth  = MONTH  <$> nchars 'M'
-    pDay    = DAY    <$> nchars 'D'
-    pHour   = HOUR   <$> nchars 'H'
-    pMinute = MINUTE <$> nchars 'm'
-    pSecond = SECOND <$> nchars 'S'
-    pFixed  = Fixed <$> (many1 $ noneOf "YMDHmS")
+    format :: FormatParser Format
+    format =
+      many1 $ choice $ map try [element YEAR 'Y', element MONTH 'M',
+                                         element DAY  'D', element HOUR  'H',
+                                         element MINUTE 'm', element SECOND 'S',
+                                         whitespaces, fixed]
 
-pYear ∷ Int → Parsec String st DateTime
+    element constr c = do
+      mandatory <- getState
+      constr mandatory <$> nchars c
+
+    whitespaces = do
+      many1 $ oneOf " \r\n\t"
+      mandatory <- getState
+      return $ Whitespace mandatory
+
+    fixed = do
+      mandatory <- getState
+      Fixed mandatory <$> (many1 $ noneOf "YMDHmS[] \t\r\n")
+
+pYear ∷ Stream s m Char => Int → ParsecT s st m DateTime
 pYear n = do
   y ← number n 10000
   if y < 2000
     then return $ mempty {year = y+2000}
     else return $ mempty {year = y}
 
-pMonth ∷ Int → Parsec String st DateTime
+pMonth ∷ Stream s m Char => Int → ParsecT s st m DateTime
 pMonth n = do
   m ← number n 12
   return $ mempty {month = m}
 
-pDay ∷ Int → Parsec String st DateTime
+pDay ∷ Stream s m Char => Int → ParsecT s st m DateTime
 pDay n = do
   d ← number n 31
   return $ mempty {day = d}
 
-pHour ∷ Int → Parsec String st DateTime
+pHour ∷ Stream s m Char => Int → ParsecT s st m DateTime
 pHour n = do
   h ← number n 23
   return $ mempty {hour = h}
 
-pMinute ∷ Int → Parsec String st DateTime
+pMinute ∷ Stream s m Char => Int → ParsecT s st m DateTime
 pMinute n = do
   m ← number n 59
   return $ mempty {minute = m}
 
-pSecond ∷ Int → Parsec String st DateTime
+pSecond ∷ Stream s m Char => Int → ParsecT s st m DateTime
 pSecond n = do
   s ← number n 59
   return $ mempty {second = s}
 
+opt :: Stream s m Char => Monoid a => Bool -> ParsecT s st m a -> ParsecT s st m a
+opt True  p = p
+opt False p = option mempty p
+
+parseFormat :: String -> Either ParseError Format
+parseFormat formatStr = runParser pFormat True "(date format string)" formatStr
+
 -- | Make Parser for specified date format.
-formatParser ∷ Format → Parsec String st DateTime
+formatParser ∷ Stream s m Char => Format → ParsecT s st m DateTime
 formatParser format = mconcat <$> mapM parser format
   where
-    parser (YEAR   n) = pYear n
-    parser (MONTH  n) = pMonth n
-    parser (DAY    n) = pDay n
-    parser (HOUR   n) = pHour n
-    parser (MINUTE n) = pMinute n
-    parser (SECOND n) = pSecond n
-    parser (Fixed s) = string s >> return mempty
+    parser (YEAR   m n) = opt m $ pYear n
+    parser (MONTH  m n) = opt m $ pMonth n
+    parser (DAY    m n) = opt m $ pDay n
+    parser (HOUR   m n) = opt m $ pHour n
+    parser (MINUTE m n) = opt m $ pMinute n
+    parser (SECOND m n) = opt m $ pSecond n
+    parser (Whitespace m) = opt m ((many1 $ oneOf " \t\r\n") >> return mempty)
+    parser (Fixed  m s) = opt m ( string s >> return mempty )
 
 -- | Parse date\/time in specified format.
 parseDateFormat :: String  -- ^ Format string, i.e. "DD.MM.YY"
                 -> String  -- ^ String to parse
                 -> Either ParseError DateTime
 parseDateFormat formatStr str = do
-  format <- runParser pFormat () "(date format string)" formatStr
+  format <- parseFormat formatStr 
   runParser (formatParser format) () "(date)" str
 
diff --git a/Data/Dates/Internal.hs b/Data/Dates/Internal.hs
--- a/Data/Dates/Internal.hs
+++ b/Data/Dates/Internal.hs
@@ -1,29 +1,29 @@
-{-# LANGUAGE UnicodeSyntax, DeriveDataTypeable #-}
+{-# LANGUAGE UnicodeSyntax, DeriveDataTypeable, FlexibleContexts #-}
 
 module Data.Dates.Internal where
 
 import Data.Char
 
 import Text.Parsec
-import Text.Parsec.String
 
 -- | Parser version of Prelude.read
-tryRead :: Read a => String -> Parsec String st a
+tryRead :: (Read a, Stream s m Char) => String -> ParsecT s st m a
 tryRead str =
   case reads str of
     [(res, "")] -> return res
     _ -> fail $ "Cannot read: " ++ str
 
-tryReadInt ∷ Num a ⇒ String → Parsec String st a
+tryReadInt ∷ (Stream s m Char, Num a) ⇒ String → ParsecT s st m a
 tryReadInt str =
   if all isDigit str
     then return $ fromIntegral $ foldl (\a b → 10*a+b) 0 $ map digitToInt str
     else fail $ "Cannot read: " ++ str
 
 -- | Apply parser N times
-times ∷ Int
-     → Parsec String st t
-     → Parsec String st [t]
+times ∷ (Stream s m Char)
+     ⇒ Int
+     → ParsecT s st m t
+     → ParsecT s st m [t]
 times 0 _ = return []
 times n p = do
   ts ← times (n-1) p
@@ -34,25 +34,26 @@
                                
 -- | Parse natural number of N digits
 -- which is not greater than M
-number ∷ Int   -- ^ Number of digits
+number ∷ Stream s m Char
+       ⇒ Int   -- ^ Number of digits
        → Int   -- ^ Maximum value
-       → Parsec String st Int
+       → ParsecT s st m Int
 number n m = do
   t ← tryReadInt =<< (n `times` digit)
   if t > m
     then fail "number too large"
     else return t
 
-pYear ∷ Parsec String st Int
+pYear ∷ Stream s m Char => ParsecT s st m Int
 pYear = do
   y ← number 4 10000
   if y < 2000
     then return (y+2000)
     else return y
 
-pMonth ∷ Parsec String st Int
+pMonth ∷ Stream s m Char => ParsecT s st m Int
 pMonth = number 2 12
 
-pDay ∷ Parsec String st Int
+pDay ∷ Stream s m Char => ParsecT s st m Int
 pDay = number 2 31
 
diff --git a/dates.cabal b/dates.cabal
--- a/dates.cabal
+++ b/dates.cabal
@@ -1,5 +1,5 @@
 name:                dates
-version:             0.2.1.2
+version:             0.2.2.0
 synopsis:            Small library for parsing different dates formats.
 description:         This package allows to parse many different formats
                      of dates. Both absolute and relative dates are supported.