diff --git a/Hascal.hs b/Hascal.hs
--- a/Hascal.hs
+++ b/Hascal.hs
@@ -1,26 +1,67 @@
-module Hascal (operators,eval,hascal) where
+-- |'Hascal' is both a simple but extendable calculator library for Haskell
+-- and a command-line program using it.
+-- 
+-- Also, its source code is a nice example for a minimalistic Haskell project.
+module Hascal (
+  -- * Functions
+  -- ** Operators
+  operators,
+  -- ** Evaluators
+  eval,
+  hascal
+  ) where
 
 import           Control.Arrow     (second)
 import           Data.Function     (on)
 import           Data.Number.CReal
 
 
-hascal :: String -> CReal
-hascal = eval operators
-
-
+-- |'operators' is the default list of operators.
+-- 
+-- An operator consists of one character and a function with of type
+-- @CReal -> CReal -> CReal@.
+-- 
+-- 'operators' includes:
+-- 
+-- * addition, represented by @\'+\'@
+-- 
+-- * subtraction, represented by @\'-\'@
+-- 
+-- * multiplication, represented by @\'c\'@
+-- 
+-- * division, represented by @\'\/\'@
+-- 
+-- * exponentiation, represented by @\'^\'@
+-- 
+-- * logarithming (with flipped arguments, see below), represented by @\'?\'@
+-- 
+-- such that these laws are held:
+-- 
+-- > (a - b == c) == (a == b + c)
+-- > (a / b == c) == (a == b * c)
+-- > (a ? b == c) == (a == b ^ c)
 operators :: [(Char, CReal -> CReal -> CReal)]
 operators = [ ('+', (+))
             , ('-', (-))
             , ('/', (/))
             , ('*', (*))
             , ('^', (**))
+            , ('?', flip logBase)
             ]-- Respecting operator precedence,
              -- you can add custom infix operators.
 
-
+-- |'eval' gets a list of operators and a string containing a mathematical
+-- expression/term which only uses those operators listed in the first
+-- argument, and returns the result of that term.
 eval :: [(Char, CReal -> CReal -> CReal)] -> String -> CReal
 eval []          a = read a
 eval l@((c,f):s) a | z /= ""   = on f (eval l.($m)) fst snd
                    | otherwise = eval s a
                    where m@(_,z) = second (drop 1) $ break (==c) a
+
+
+-- |'hascal' is the default evaluator:
+-- 
+-- > hascal = eval operators
+hascal :: String -> CReal
+hascal = eval operators
diff --git a/hascal.cabal b/hascal.cabal
--- a/hascal.cabal
+++ b/hascal.cabal
@@ -1,9 +1,10 @@
 name:                hascal
-version:             1
+version:             1.1
 synopsis:            a minimal, extensible and precise calculator
 description:         Hascal is a minimal calculator with infix-operations
-                     supporting addition, subtraction, division, multiplication
-		     and exponentiation. Brackets are not supported yet.
+                     supporting addition, subtraction, division, multiplication,
+		     exponentiation and logarithming. Brackets are not supported
+		     yet.
 		     Futhermore, it's easy to add custom operators.
 stability:           provisional
 category:            Math, Console, Tools, Utility, Utils, Parsing