diff --git a/library/Text/Builder.hs b/library/Text/Builder.hs
--- a/library/Text/Builder.hs
+++ b/library/Text/Builder.hs
@@ -1,9 +1,11 @@
 module Text.Builder
 (
   Builder,
+  -- * Accessors
   run,
   length,
   null,
+  -- * Constructors
   intercalate,
   char,
   text,
@@ -18,10 +20,13 @@
   utf8CodeUnits4,
   decimal,
   unsignedDecimal,
+  thousandSeparatedDecimal,
+  thousandSeparatedUnsignedDecimal,
   decimalDigit,
   hexadecimal,
   unsignedHexadecimal,
   hexadecimalDigit,
+  padFromLeft,
 )
 where
 
@@ -32,28 +37,32 @@
 import qualified Data.Text.Encoding.Error as E
 import qualified Text.Builder.UTF16 as D
 import qualified Data.ByteString as ByteString
+import qualified DeferredFolds.Unfoldr as Unfoldr
+import qualified Data.Text as Text
 
 
 newtype Action =
   Action (forall s. B.MArray s -> Int -> ST s ())
 
 data Builder =
-  Builder !Action !Int
+  Builder !Action !Int !Int
 
 instance Monoid Builder where
   {-# INLINE mempty #-}
   mempty =
-    Builder (Action (\_ _ -> return ())) 0
+    Builder (Action (\_ _ -> return ())) 0 0
   {-# INLINABLE mappend #-}
-  mappend (Builder (Action action1) size1) (Builder (Action action2) size2) =
-    Builder action size
+  mappend (Builder (Action action1) arraySize1 charsAmount1) (Builder (Action action2) arraySize2 charsAmount2) =
+    Builder action arraySize charsAmount
     where
       action =
         Action $ \array offset -> do
           action1 array offset
-          action2 array (offset + size1)
-      size =
-        size1 + size2
+          action2 array (offset + arraySize1)
+      arraySize =
+        arraySize1 + arraySize2
+      charsAmount =
+        charsAmount1 + charsAmount2
 
 instance Semigroup Builder where
   (<>) = mappend
@@ -61,6 +70,32 @@
 instance IsString Builder where
   fromString = string
 
+
+-- * Accessors
+-------------------------
+
+{-# INLINE length #-}
+length :: Builder -> Int
+length (Builder _ _ x) = x
+
+{-# INLINE null #-}
+null :: Builder -> Bool
+null = (== 0) . length
+
+run :: Builder -> Text
+run (Builder (Action action) arraySize _) =
+  C.text array 0 arraySize
+  where
+    array =
+      runST $ do
+        array <- B.new arraySize
+        action array 0
+        B.unsafeFreeze array
+
+
+-- * Constructors
+-------------------------
+
 {-# INLINE char #-}
 char :: Char -> Builder
 char x =
@@ -74,7 +109,7 @@
 {-# INLINABLE utf16CodeUnits1 #-}
 utf16CodeUnits1 :: Word16 -> Builder
 utf16CodeUnits1 unit =
-  Builder action 1
+  Builder action 1 1
   where
     action =
       Action $ \array offset -> B.unsafeWrite array offset unit
@@ -82,7 +117,7 @@
 {-# INLINABLE utf16CodeUnits2 #-}
 utf16CodeUnits2 :: Word16 -> Word16 -> Builder
 utf16CodeUnits2 unit1 unit2 =
-  Builder action 2
+  Builder action 2 1
   where
     action =
       Action $ \array offset -> do
@@ -112,8 +147,9 @@
 {-# INLINABLE asciiByteString #-}
 asciiByteString :: ByteString -> Builder
 asciiByteString byteString =
-  Builder action (ByteString.length byteString)
+  Builder action length length
   where
+    length = ByteString.length byteString
     action =
       Action $ \array -> let
         step byte next index = do
@@ -123,8 +159,8 @@
 
 {-# INLINABLE text #-}
 text :: Text -> Builder
-text (C.Text array offset length) =
-  Builder action length
+text text@(C.Text array offset length) =
+  Builder action length (Text.length text)
   where
     action =
       Action $ \builderArray builderOffset -> do
@@ -145,17 +181,24 @@
 {-# INLINABLE unsignedDecimal #-}
 unsignedDecimal :: Integral a => a -> Builder
 unsignedDecimal =
-  loop mempty
-  where
-    loop builder !i =
-      case quotRem i 10 of
-        (quot, !rem) ->
-          case hexadecimalDigit rem <> builder of
-            newBuilder ->
-              if quot /= 0
-                then loop newBuilder quot
-                else newBuilder
+  foldMap decimalDigit . Unfoldr.digits
 
+{-# INLINABLE thousandSeparatedDecimal #-}
+thousandSeparatedDecimal :: Integral a => Char -> a -> Builder
+thousandSeparatedDecimal separatorChar a =
+  if a >= 0
+    then thousandSeparatedUnsignedDecimal separatorChar a
+    else unicodeCodePoint 45 <> thousandSeparatedUnsignedDecimal separatorChar (negate a)
+
+{-# INLINABLE thousandSeparatedUnsignedDecimal #-}
+thousandSeparatedUnsignedDecimal :: Integral a => Char -> a -> Builder
+thousandSeparatedUnsignedDecimal separatorChar a =
+  fold $ do
+    (index, digit) <- Unfoldr.zipWithReverseIndex $ Unfoldr.digits a
+    if mod index 3 == 0 && index /= 0
+      then return (decimalDigit digit <> char separatorChar)
+      else return (decimalDigit digit)
+
 {-# INLINE hexadecimal #-}
 hexadecimal :: Integral a => a -> Builder
 hexadecimal i =
@@ -189,14 +232,6 @@
     then unicodeCodePoint (fromIntegral n + 48)
     else unicodeCodePoint (fromIntegral n + 87)
 
-{-# INLINE length #-}
-length :: Builder -> Int
-length (Builder _ x) = x
-
-{-# INLINE null #-}
-null :: Builder -> Bool
-null = (== 0) . length
-
 {-# INLINE intercalate #-}
 intercalate :: Foldable foldable => Builder -> foldable Builder -> Builder
 intercalate separator = extract . foldl' step init where
@@ -206,12 +241,10 @@
     else element
   extract (Product2 _ builder) = builder
 
-run :: Builder -> Text
-run (Builder (Action action) size) =
-  C.text array 0 size
-  where
-    array =
-      runST $ do
-        array <- B.new size
-        action array 0
-        B.unsafeFreeze array
+{-# INLINABLE padFromLeft #-}
+padFromLeft :: Int -> Char -> Builder -> Builder
+padFromLeft paddedLength paddingChar builder = let
+  builderLength = length builder
+  in if paddedLength <= builderLength
+    then builder
+    else foldMap char (replicate (paddedLength - builderLength) paddingChar) <> builder
diff --git a/library/Text/Builder/Prelude.hs b/library/Text/Builder/Prelude.hs
--- a/library/Text/Builder/Prelude.hs
+++ b/library/Text/Builder/Prelude.hs
@@ -81,4 +81,8 @@
 -------------------------
 import Data.Text as Exports (Text)
 
+-- deferred-folds
+-------------------------
+import DeferredFolds.Unfoldr as Exports (Unfoldr(..))
+
 data Product2 a b = Product2 !a !b
diff --git a/test/Main.hs b/test/Main.hs
--- a/test/Main.hs
+++ b/test/Main.hs
@@ -57,6 +57,19 @@
     testProperty "Hexadecimal vs std show" $ \ (x :: Integer) -> x >= 0 ==>
     (fromString . showHex x) "" === (B.run . B.hexadecimal) x
     ,
+    testCase "Separated thousands" $ do
+      assertEqual "" "0" (B.run (B.thousandSeparatedUnsignedDecimal ',' 0))
+      assertEqual "" "123" (B.run (B.thousandSeparatedUnsignedDecimal ',' 123))
+      assertEqual "" "1,234" (B.run (B.thousandSeparatedUnsignedDecimal ',' 1234))
+      assertEqual "" "1,234,567" (B.run (B.thousandSeparatedUnsignedDecimal ',' 1234567))
+    ,
+    testCase "Pad from left" $ do
+      assertEqual "" "00" (B.run (B.padFromLeft 2 '0' ""))
+      assertEqual "" "00" (B.run (B.padFromLeft 2 '0' "0"))
+      assertEqual "" "01" (B.run (B.padFromLeft 2 '0' "1"))
+      assertEqual "" "12" (B.run (B.padFromLeft 2 '0' "12"))
+      assertEqual "" "123" (B.run (B.padFromLeft 2 '0' "123"))
+    ,
     testCase "Hexadecimal" $
     assertEqual "" "1f23" (B.run (B.hexadecimal 0x01f23))
     ,
diff --git a/text-builder.cabal b/text-builder.cabal
--- a/text-builder.cabal
+++ b/text-builder.cabal
@@ -1,5 +1,5 @@
 name: text-builder
-version: 0.5.4.3
+version: 0.6
 category: Text
 synopsis: An efficient strict text builder
 homepage: https://github.com/nikita-volkov/text-builder
@@ -25,6 +25,7 @@
     base >=4.9 && <5,
     base-prelude <2,
     bytestring >=0.10 && <0.11,
+    deferred-folds >=0.8 && <0.9,
     semigroups >=0.18 && <0.19,
     text >=1 && <2