diff --git a/Data/Text/Format/Heavy/Instances.hs b/Data/Text/Format/Heavy/Instances.hs
--- a/Data/Text/Format/Heavy/Instances.hs
+++ b/Data/Text/Format/Heavy/Instances.hs
@@ -3,6 +3,9 @@
 module Data.Text.Format.Heavy.Instances
   (-- * Utility data types
    Single (..), Several (..), Shown (..),
+   -- * Combinators
+   DefaultValue (..), ThenCheck (..),
+   withDefault, optional,
    -- * Generic formatters
    genericIntFormat, genericFloatFormat
   ) where
@@ -12,6 +15,7 @@
 import Data.Default
 import Data.Word
 import Data.Int
+import Data.Maybe
 import qualified Data.Map as M
 import qualified Data.Text as T
 import qualified Data.Text.Encoding as TE
@@ -271,4 +275,26 @@
 
 instance Formatable x => VarContainer (M.Map TL.Text x) where
   lookupVar name pairs = Variable `fmap` M.lookup name pairs
+
+-- | Variable container which contains fixed value for any variable name.
+data DefaultValue = DefaultValue Variable
+
+instance VarContainer DefaultValue where
+  lookupVar _ (DefaultValue var) = Just var
+
+-- | Combiled variable container, which uses parameters from @c1@,
+-- and if variable is not found there it will check in @c2@.
+data ThenCheck c1 c2 = ThenCheck c1 c2
+
+instance (VarContainer c1, VarContainer c2) => VarContainer (ThenCheck c1 c2) where
+  lookupVar name (ThenCheck c1 c2) =
+    case lookupVar name c1 of
+      Just result -> Just result
+      Nothing -> lookupVar name c2
+
+withDefault :: VarContainer c => c -> Variable -> ThenCheck c DefaultValue
+withDefault c value = c `ThenCheck` DefaultValue value
+
+optional :: VarContainer c => c -> ThenCheck c DefaultValue
+optional c = c `withDefault` (Variable TL.empty)
 
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -20,6 +20,17 @@
 parsed from lazy Text, or can be entered as string literals, since `Format`
 implements `IsString`.
 
+There are two syntaxes of formatting strings defined by this package:
+
+* Default Python-like syntax, which is generally described as "anything in
+  braces is a variable substitution". `instance IsString Format` uses this
+  syntax.
+* Alternative Shell-like syntax, which is generally described as "anything
+  after dollar sign is a variable substitution".
+
+It is possible to implement custom syntaxes of format strings: you just need to
+parse instances of `Format` type from some sort of strings.
+
 The `format` function takes a `Format` specification and a container with
 variables. Container types are generalized by `VarContainer` type class.
 Standard container implementations include:
@@ -37,9 +48,9 @@
 integers, floats and strings, python-like syntax is used. Standard set of
 variable types includes:
 
- * Integers (`Int` and `Integer`, others can be easily added);
+ * Integers (`Int`, `Integer`, `Int8..64`, `Word8..64`, others can be easily added);
  * Floats (`Float` and `Double`);
- * Strings (`String`, lazy and strict `Text`);
+ * Strings (`String`, lazy and strict `ByteString`, lazy and strict `Text`);
  * Booleans;
  * Time/date values from Data.Time.
  * Any instance of `Show` type class can be used by packing it into `Shown`
@@ -47,9 +58,10 @@
 
 One can implement custom variable types.
 
-For examples, please refer to [GitHub
-wiki](https://github.com/portnov/text-format-heavy/wiki) and `examples/`
+For examples, please refer to [GitHub wiki][1] and `examples/`
 directory in this repo. There are also some examples in haddock documentation.
 
 License: BSD3.
+
+[1]: https://github.com/portnov/text-format-heavy/wiki
 
diff --git a/text-format-heavy.cabal b/text-format-heavy.cabal
--- a/text-format-heavy.cabal
+++ b/text-format-heavy.cabal
@@ -1,5 +1,5 @@
 name:                text-format-heavy
-version:             0.1.3.0
+version:             0.1.4.0
 synopsis:            Full-weight string formatting library, analog of Python's string.format
 description:         This package contains full-featured string formatting function, similar to
                      Python's string.format. Features include: