diff --git a/Calculator.hs b/Calculator.hs
deleted file mode 100644
--- a/Calculator.hs
+++ /dev/null
@@ -1,155 +0,0 @@
----------------------------------------------------------
---
--- Module        : Caclulator
--- Copyright     : Bartosz Wójcik (2012)
--- License       : BSD3
---
--- Maintainer    : bartek@sudety.it
--- Stability     : Unstable
--- Portability   : portable
---
--- Module is part of Wojcik Tool Kit package.
--- | Simple calculator. Evaluates arithmetic formulas.
----------------------------------------------------------
-{-# LANGUAGE TypeSynonymInstances, FlexibleInstances, NoMonomorphismRestriction #-}
-module Calculator (
-       evaluate     -- Evaluates arithmetic formula.       
-      ,evaluateInt  -- Evaluates arithmetic formula on @Integer@s.
-                  )
-where
-
-import Control.Monad
-import Control.Monad.Trans.Error
-import Control.Monad.Trans.State
-import Control.Monad.Trans.Class
-import Data.Char
-import Data.Either
-import Text.WtkParser
-
-
-
--- | State contains just operator
-type State1 a = (a -> a -> a)
-
--- | Only limited operators are available, 
---   they are shown using some trick.
-instance (Num a) => Show (State1 a) where
-   show f | 3 `f` 2 == 6 = "*"
-          | 3 `f` 2 == 5 = "+"
-          | 3 `f` 2 == 1 = "-"
-          | 3 `f` 2 == 8 = "^"
-          | otherwise    = "/"
-
--- | Calculator parser is just simple wtk parser with added state.
---   State keeps not yet consumed operator.
-type Parser1 a = StateT (State1 a) Parser a
-
-runParser1 :: (Num a) => State1 a -> Parser1 a -> String -> Either String (String, (a, (State1 a)))
-runParser1 st e = runParser $ runStateT e st
-
--- | Evaluates arithmetic formula. In case formula cannot be parsed
---   returns error message.
-evaluate :: (Floating a, RealFrac a, Ord a) => String -> Either String a
-evaluate x = case runParser1 (+) arithmetic x of
-             Left err          -> Left err
-             Right (_,(res,_)) -> Right res
-
--- | Integer version of @evaluate@.
-evaluateInt :: String -> Either String Integer
-evaluateInt x = case runParser1 (+) arithmeticInt x of
-                     Left err          -> Left err
-                     Right (_,(res,_)) -> Right res
-
-char1  = lift . lexeme . char
-
-finito n = (char1 '=' >> lift eof) `mplus` lift eof >> return n
-
-arithmetic = lift skipSpaces >> expression1 >>= finito
-arithmeticInt = lift skipSpaces >> expressionInt >>= finito
-
--- "runStateT p f" transforms "Parser1 a" to "Parser (a,s)"
--- "liftM fst" changes it to "Parser a" which gives us proper type
--- for manyF function. Then in turn we lift result of manyF from "Parser a"
--- to "Parser1 a".
-manyF11 :: (Num a) => Parser1 a -> a -> Parser1 a
-manyF11 p n = do
-         f <- get
-         lift $ manyF f (liftM fst (runStateT p f)) n
-
-manyF1 :: (Num a) => Parser1 a -> a -> Parser1 a
-manyF1 p n = StateT many'
-   where many' f = Parser many''
-         many'' x =
-            case runParser1 (-) p x of
-               Left err -> Right (x,(n,(-)))
-               Right (x',(a,f)) -> do
-                  let Right (x'',(rest,_)) = many'' x'
-                  Right (x'',(rest `f` a,f))
-
-myPut :: (Monad m) => s -> a -> StateT s m a
-myPut s a = StateT $ \_ -> return (a, s)
-
-expression1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
-expression1 = term1 >>= manyF1 (tMinus1 `mplus` tPlus1)
-
-tMinus1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
-tMinus1 = char1 '-' >> term1 >>= myPut (-)
-
-tPlus1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
-tPlus1 = char1 '+' >> term1 >>= myPut (+)
-
-term1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
-term1 = tPower1 >>= manyF1 (tMult1 `mplus` tDiv1)
-
-tMult1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
-tMult1 = char1 '*' >> tPower1 >>= myPut (*)
-
-tDiv1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
-tDiv1 = char1 '/' >> tPower1 >>= myPut (/)
-
-tPower1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
-tPower1 = tFactorial1 >>= manyF1 tPow1
-
-tPow1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
-tPow1 = char1 '^' >> tFactorial1 >>= myPut (**)
-
-tFactorial1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
-tFactorial1 = phrase1 >>= manyF1 tFact1
-
-tFact1 :: (RealFrac a, Ord a) => Parser1 a
-tFact1 = char1 '!' >> return 1 >>= myPut (\a b -> fromIntegral (product [1 .. round a]))
-
-phrase1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
-phrase1 = (do
-            char1 '('
-            v <- expression1
-            char1 ')'
-            return v)
-         `mplus` lift (lexeme real)
-
-expressionInt = termInt >>= manyF1 (tMinusInt `mplus` tPlusInt)
-
-tMinusInt = char1 '-' >> termInt >>= myPut (-)
-
-tPlusInt = char1 '+' >> termInt >>= myPut (+)
-
-termInt = tPowerInt >>= manyF1 (tMultInt `mplus` tDivInt)
-
-tMultInt = char1 '*' >> tPowerInt >>= myPut (*)
-
-tDivInt = char1 '/' >> tPowerInt >>= myPut div
-
-tPowerInt = tFactorialInt >>= manyF1 tPowInt
-
-tPowInt = char1 '^' >> tFactorialInt >>= myPut (^)
-
-tFactorialInt = phraseInt >>= manyF1 tFactInt
-
-tFactInt = char1 '!' >> return 1 >>= myPut (\a b -> product [1 .. a])
-
-phraseInt = (do
-            char1 '('
-            v <- expressionInt
-            char1 ')'
-            return v)
-         `mplus` lift (lexeme intSigned)
diff --git a/ReadEither.hs b/ReadEither.hs
deleted file mode 100644
--- a/ReadEither.hs
+++ /dev/null
@@ -1,123 +0,0 @@
----------------------------------------------------------
---
--- Module        : ReadEither
--- Copyright     : Bartosz Wójcik (2012)
--- License       : BSD3
---
--- Maintainer    : bartek@sudety.it
--- Stability     : Unstable
--- Portability   : portable
---
--- Module is part of Wojcik Tool Kit package.
--- | Safe version of Read with human friendly error messages.
----------------------------------------------------------
-
-
-{-# LANGUAGE TypeSynonymInstances #-}
-
-module ReadEither
-where
-
-import Control.Monad (liftM)
-import Control.Monad.Trans.Error
-import Data.Char
-import Data.Maybe
-import Data.Time
-import System.Locale
-import Text.WtkParser
-import Calculator
-
-
--- | Type class providing simple input parsing
-class (Show a) => ReadEither a where
-      readEither :: String -> Either String a  -- ^ Parses String to given readEither or returns error message.
-
-instance ReadEither () where
-         readEither _ = Right ()
-
-instance ReadEither Char where
-         readEither [] = Left "Empty string"
-         readEither x  = Right $ head x
-         
-instance ReadEither String where
-         readEither = Right
-
-instance ReadEither Bool where
-         readEither " " = Right False
-         readEither "0" = Right False
-         readEither "False" = Right False
-         readEither _   = Right True
-
-instance ReadEither Integer where
-         readEither = eval intSigned
-
-instance ReadEither Int where
-         readEither x = eval intSigned x >>= return . fromIntegral  
-
-instance ReadEither Double where
-         readEither = eval real 
-
-instance ReadEither Float where
-         readEither x = eval real x >>= return . realToFrac 
-
--- | Parsing to Day can be done on many ways. For details see the source code.
-instance ReadEither Day where
-         readEither x = readEither' localeList
-            where readEither' [] = Left "Date doesn't fit to the expected format" 
-                  readEither' (l:ls) = case parseTime defaultTimeLocale l x of
-                                       Just d  -> Right d
-                                       Nothing -> readEither' ls
-
---  List of all parsable formats.
---  Month name only in english due to usage of @defaultTimeLocale@.
-localeList = ["%Y %m %d"  -- 2000 11 10
-             ,"%Y %b %d"  -- 2000 Nov 10
-             ,"%Y-%m-%d"  -- 2000-11-10
-             ,"%d %m %Y"  -- 10 11 2000
-             ,"%d %b %Y"  -- 10 Nov 2000
-             ,"%d.%m.%Y"  -- 10.11.2000
-             ,"%Y.%m.%d"  -- 2000.11.10
-             ,"%d-%m-%Y"  -- 10-11-2000
-             ,"%Y/%m/%d"  -- 2000/11/10
-             ,"%d/%m/%Y"  -- 10/11/2000
-             ,"%d/%m/%y"  -- 10/11/00
-             ,"%y %m %d"  -- 00 11 10
-             ,"%d%m%y"    -- 101100
-             ,"%d%m%Y"    -- 10112000
-             ,"%y%m%d"    -- 0011210
-             ,"%Y%m%d"    -- 200011210
-             ]
-
-instance ReadEither a => ReadEither (Maybe a) where
-   readEither "" = Right Nothing
-   readEither x  = liftM Just $ readEither x
-
-
--- | Type class providing input parsing with additional features.
-class (ReadEither a) => ReadEitherPlus a where
-      readEitherPlus :: String -> Either String a  -- ^ Parses String to given readEither or returns error message.
-
--- | Strips out all control charaters
-instance ReadEitherPlus String where
-         readEitherPlus = Right . filter (\x -> ord x >= 32)
-
--- | Parses arithmetic formula
-instance ReadEitherPlus Double where
-         readEitherPlus = evaluate
-
--- | Parses arithmetic formula
-instance ReadEitherPlus Float where
-         readEitherPlus = liftM realToFrac . evaluate
-
--- | Parses arithmetic formula
-instance ReadEitherPlus Integer where
-         readEitherPlus = evaluateInt
-
--- | Parses arithmetic formula
-instance ReadEitherPlus Int where
-         readEitherPlus = liftM fromIntegral . evaluateInt
-
-instance ReadEitherPlus a => ReadEitherPlus (Maybe a) where
-   readEitherPlus "" = Right Nothing
-   readEitherPlus x  = liftM Just $ readEitherPlus x
-
diff --git a/Text/Calculator.hs b/Text/Calculator.hs
new file mode 100644
--- /dev/null
+++ b/Text/Calculator.hs
@@ -0,0 +1,155 @@
+---------------------------------------------------------
+--
+-- Module        : Caclulator
+-- Copyright     : Bartosz Wójcik (2012)
+-- License       : BSD3
+--
+-- Maintainer    : bartek@sudety.it
+-- Stability     : Unstable
+-- Portability   : portable
+--
+-- Module is part of Wojcik Tool Kit package.
+-- | Simple calculator. Evaluates arithmetic formulas.
+---------------------------------------------------------
+{-# LANGUAGE TypeSynonymInstances, FlexibleInstances, NoMonomorphismRestriction #-}
+module Text.Calculator (
+       evaluate     -- Evaluates arithmetic formula.       
+      ,evaluateInt  -- Evaluates arithmetic formula on @Integer@s.
+                  )
+where
+
+import Control.Monad
+import Control.Monad.Trans.Error
+import Control.Monad.Trans.State
+import Control.Monad.Trans.Class
+import Data.Char
+import Data.Either
+import Text.WtkParser
+
+
+
+-- | State contains just operator
+type State1 a = (a -> a -> a)
+
+-- | Only limited operators are available, 
+--   they are shown using some trick.
+instance (Num a) => Show (State1 a) where
+   show f | 3 `f` 2 == 6 = "*"
+          | 3 `f` 2 == 5 = "+"
+          | 3 `f` 2 == 1 = "-"
+          | 3 `f` 2 == 8 = "^"
+          | otherwise    = "/"
+
+-- | Calculator parser is just simple wtk parser with added state.
+--   State keeps not yet consumed operator.
+type Parser1 a = StateT (State1 a) Parser a
+
+runParser1 :: (Num a) => State1 a -> Parser1 a -> String -> Either String (String, (a, (State1 a)))
+runParser1 st e = runParser $ runStateT e st
+
+-- | Evaluates arithmetic formula. In case formula cannot be parsed
+--   returns error message.
+evaluate :: (Floating a, RealFrac a, Ord a) => String -> Either String a
+evaluate x = case runParser1 (+) arithmetic x of
+             Left err          -> Left err
+             Right (_,(res,_)) -> Right res
+
+-- | Integer version of @evaluate@.
+evaluateInt :: String -> Either String Integer
+evaluateInt x = case runParser1 (+) arithmeticInt x of
+                     Left err          -> Left err
+                     Right (_,(res,_)) -> Right res
+
+char1  = lift . lexeme . char
+
+finito n = (char1 '=' >> lift eof) `mplus` lift eof >> return n
+
+arithmetic = lift skipSpaces >> expression1 >>= finito
+arithmeticInt = lift skipSpaces >> expressionInt >>= finito
+
+-- "runStateT p f" transforms "Parser1 a" to "Parser (a,s)"
+-- "liftM fst" changes it to "Parser a" which gives us proper type
+-- for manyF function. Then in turn we lift result of manyF from "Parser a"
+-- to "Parser1 a".
+manyF11 :: (Num a) => Parser1 a -> a -> Parser1 a
+manyF11 p n = do
+         f <- get
+         lift $ manyF f (liftM fst (runStateT p f)) n
+
+manyF1 :: (Num a) => Parser1 a -> a -> Parser1 a
+manyF1 p n = StateT many'
+   where many' f = Parser many''
+         many'' x =
+            case runParser1 (-) p x of
+               Left err -> Right (x,(n,(-)))
+               Right (x',(a,f)) -> do
+                  let Right (x'',(rest,_)) = many'' x'
+                  Right (x'',(rest `f` a,f))
+
+myPut :: (Monad m) => s -> a -> StateT s m a
+myPut s a = StateT $ \_ -> return (a, s)
+
+expression1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
+expression1 = term1 >>= manyF1 (tMinus1 `mplus` tPlus1)
+
+tMinus1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
+tMinus1 = char1 '-' >> term1 >>= myPut (-)
+
+tPlus1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
+tPlus1 = char1 '+' >> term1 >>= myPut (+)
+
+term1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
+term1 = tPower1 >>= manyF1 (tMult1 `mplus` tDiv1)
+
+tMult1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
+tMult1 = char1 '*' >> tPower1 >>= myPut (*)
+
+tDiv1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
+tDiv1 = char1 '/' >> tPower1 >>= myPut (/)
+
+tPower1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
+tPower1 = tFactorial1 >>= manyF1 tPow1
+
+tPow1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
+tPow1 = char1 '^' >> tFactorial1 >>= myPut (**)
+
+tFactorial1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
+tFactorial1 = phrase1 >>= manyF1 tFact1
+
+tFact1 :: (RealFrac a, Ord a) => Parser1 a
+tFact1 = char1 '!' >> return 1 >>= myPut (\a b -> fromIntegral (product [1 .. round a]))
+
+phrase1 :: (Floating a, RealFrac a, Ord a) => Parser1 a
+phrase1 = (do
+            char1 '('
+            v <- expression1
+            char1 ')'
+            return v)
+         `mplus` lift (lexeme real)
+
+expressionInt = termInt >>= manyF1 (tMinusInt `mplus` tPlusInt)
+
+tMinusInt = char1 '-' >> termInt >>= myPut (-)
+
+tPlusInt = char1 '+' >> termInt >>= myPut (+)
+
+termInt = tPowerInt >>= manyF1 (tMultInt `mplus` tDivInt)
+
+tMultInt = char1 '*' >> tPowerInt >>= myPut (*)
+
+tDivInt = char1 '/' >> tPowerInt >>= myPut div
+
+tPowerInt = tFactorialInt >>= manyF1 tPowInt
+
+tPowInt = char1 '^' >> tFactorialInt >>= myPut (^)
+
+tFactorialInt = phraseInt >>= manyF1 tFactInt
+
+tFactInt = char1 '!' >> return 1 >>= myPut (\a b -> product [1 .. a])
+
+phraseInt = (do
+            char1 '('
+            v <- expressionInt
+            char1 ')'
+            return v)
+         `mplus` lift (lexeme intSigned)
diff --git a/Text/PrettyShow.hs b/Text/PrettyShow.hs
--- a/Text/PrettyShow.hs
+++ b/Text/PrettyShow.hs
@@ -11,7 +11,7 @@
 -- | Type class Show-like formating numbers for humans.
 ---------------------------------------------------------
 
-{-# LANGUAGE TypeSynonymInstances #-}
+{-# LANGUAGE TypeSynonymInstances,FlexibleInstances #-}
 
 module Text.PrettyShow
    (PrettyShow             -- type class providing following functions
diff --git a/Text/ReadEither.hs b/Text/ReadEither.hs
new file mode 100644
--- /dev/null
+++ b/Text/ReadEither.hs
@@ -0,0 +1,123 @@
+---------------------------------------------------------
+--
+-- Module        : ReadEither
+-- Copyright     : Bartosz Wójcik (2012)
+-- License       : BSD3
+--
+-- Maintainer    : bartek@sudety.it
+-- Stability     : Unstable
+-- Portability   : portable
+--
+-- Module is part of Wojcik Tool Kit package.
+-- | Safe version of Read with human friendly error messages.
+---------------------------------------------------------
+
+
+{-# LANGUAGE TypeSynonymInstances, FlexibleInstances #-}
+
+module Text.ReadEither
+where
+
+import Control.Monad (liftM)
+import Control.Monad.Trans.Error
+import Data.Char
+import Data.Maybe
+import Data.Time
+import System.Locale
+import Text.WtkParser
+import Text.Calculator
+
+
+-- | Type class providing simple input parsing
+class (Show a) => ReadEither a where
+      readEither :: String -> Either String a  -- ^ Parses String to given readEither or returns error message.
+
+instance ReadEither () where
+         readEither _ = Right ()
+
+instance ReadEither Char where
+         readEither [] = Left "Empty string"
+         readEither x  = Right $ head x
+         
+instance ReadEither String where
+         readEither = Right
+
+instance ReadEither Bool where
+         readEither " " = Right False
+         readEither "0" = Right False
+         readEither "False" = Right False
+         readEither _   = Right True
+
+instance ReadEither Integer where
+         readEither = eval intSigned
+
+instance ReadEither Int where
+         readEither x = eval intSigned x >>= return . fromIntegral  
+
+instance ReadEither Double where
+         readEither = eval real 
+
+instance ReadEither Float where
+         readEither x = eval real x >>= return . realToFrac 
+
+-- | Parsing to Day can be done on many ways. For details see the source code.
+instance ReadEither Day where
+         readEither x = readEither' localeList
+            where readEither' [] = Left "Date doesn't fit to the expected format" 
+                  readEither' (l:ls) = case parseTime defaultTimeLocale l x of
+                                       Just d  -> Right d
+                                       Nothing -> readEither' ls
+
+--  List of all parsable formats.
+--  Month name only in english due to usage of @defaultTimeLocale@.
+localeList = ["%Y %m %d"  -- 2000 11 10
+             ,"%Y %b %d"  -- 2000 Nov 10
+             ,"%Y-%m-%d"  -- 2000-11-10
+             ,"%d %m %Y"  -- 10 11 2000
+             ,"%d %b %Y"  -- 10 Nov 2000
+             ,"%d.%m.%Y"  -- 10.11.2000
+             ,"%Y.%m.%d"  -- 2000.11.10
+             ,"%d-%m-%Y"  -- 10-11-2000
+             ,"%Y/%m/%d"  -- 2000/11/10
+             ,"%d/%m/%Y"  -- 10/11/2000
+             ,"%d/%m/%y"  -- 10/11/00
+             ,"%y %m %d"  -- 00 11 10
+             ,"%d%m%y"    -- 101100
+             ,"%d%m%Y"    -- 10112000
+             ,"%y%m%d"    -- 0011210
+             ,"%Y%m%d"    -- 200011210
+             ]
+
+instance ReadEither a => ReadEither (Maybe a) where
+   readEither "" = Right Nothing
+   readEither x  = liftM Just $ readEither x
+
+
+-- | Type class providing input parsing with additional features.
+class (ReadEither a) => ReadEitherPlus a where
+      readEitherPlus :: String -> Either String a  -- ^ Parses String to given readEither or returns error message.
+
+-- | Strips out all control charaters
+instance ReadEitherPlus String where
+         readEitherPlus = Right . filter (\x -> ord x >= 32)
+
+-- | Parses arithmetic formula
+instance ReadEitherPlus Double where
+         readEitherPlus = evaluate
+
+-- | Parses arithmetic formula
+instance ReadEitherPlus Float where
+         readEitherPlus = liftM realToFrac . evaluate
+
+-- | Parses arithmetic formula
+instance ReadEitherPlus Integer where
+         readEitherPlus = evaluateInt
+
+-- | Parses arithmetic formula
+instance ReadEitherPlus Int where
+         readEitherPlus = liftM fromIntegral . evaluateInt
+
+instance ReadEitherPlus a => ReadEitherPlus (Maybe a) where
+   readEitherPlus "" = Right Nothing
+   readEitherPlus x  = liftM Just $ readEitherPlus x
+
diff --git a/wtk.cabal b/wtk.cabal
--- a/wtk.cabal
+++ b/wtk.cabal
@@ -1,11 +1,11 @@
 Name:		wtk
-Version:	0.1
-License:	BSD3
+Version:	0.2
+License:	BSD3
 License-file: license
 Author:		Bartosz Wojcik
 Maintainer:	Bartosz Wojcik <bartoszmwojcik@gmail.com>
 Copyright:  Copyright (c) 2012 Bartosz Wojcik
-Category:	Tool Kit
+Category:	Utils
 Synopsis:	Wojcik Tool Kit
 Stability:  experimental
 Build-type:	Simple
@@ -15,8 +15,8 @@
 
 library
   Build-Depends:	base >= 3 && < 5, old-locale, time, transformers
-  Exposed-Modules: ReadEither
-                   Calculator
+  Exposed-Modules: Text.ReadEither
+                   Text.Calculator
                    Text.PrettyShow
   Other-Modules: Text.WtkParser