diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,373 @@
+Mozilla Public License Version 2.0
+==================================
+
+1. Definitions
+--------------
+
+1.1. "Contributor"
+    means each individual or legal entity that creates, contributes to
+    the creation of, or owns Covered Software.
+
+1.2. "Contributor Version"
+    means the combination of the Contributions of others (if any) used
+    by a Contributor and that particular Contributor's Contribution.
+
+1.3. "Contribution"
+    means Covered Software of a particular Contributor.
+
+1.4. "Covered Software"
+    means Source Code Form to which the initial Contributor has attached
+    the notice in Exhibit A, the Executable Form of such Source Code
+    Form, and Modifications of such Source Code Form, in each case
+    including portions thereof.
+
+1.5. "Incompatible With Secondary Licenses"
+    means
+
+    (a) that the initial Contributor has attached the notice described
+        in Exhibit B to the Covered Software; or
+
+    (b) that the Covered Software was made available under the terms of
+        version 1.1 or earlier of the License, but not also under the
+        terms of a Secondary License.
+
+1.6. "Executable Form"
+    means any form of the work other than Source Code Form.
+
+1.7. "Larger Work"
+    means a work that combines Covered Software with other material, in
+    a separate file or files, that is not Covered Software.
+
+1.8. "License"
+    means this document.
+
+1.9. "Licensable"
+    means having the right to grant, to the maximum extent possible,
+    whether at the time of the initial grant or subsequently, any and
+    all of the rights conveyed by this License.
+
+1.10. "Modifications"
+    means any of the following:
+
+    (a) any file in Source Code Form that results from an addition to,
+        deletion from, or modification of the contents of Covered
+        Software; or
+
+    (b) any new file in Source Code Form that contains any Covered
+        Software.
+
+1.11. "Patent Claims" of a Contributor
+    means any patent claim(s), including without limitation, method,
+    process, and apparatus claims, in any patent Licensable by such
+    Contributor that would be infringed, but for the grant of the
+    License, by the making, using, selling, offering for sale, having
+    made, import, or transfer of either its Contributions or its
+    Contributor Version.
+
+1.12. "Secondary License"
+    means either the GNU General Public License, Version 2.0, the GNU
+    Lesser General Public License, Version 2.1, the GNU Affero General
+    Public License, Version 3.0, or any later versions of those
+    licenses.
+
+1.13. "Source Code Form"
+    means the form of the work preferred for making modifications.
+
+1.14. "You" (or "Your")
+    means an individual or a legal entity exercising rights under this
+    License. For legal entities, "You" includes any entity that
+    controls, is controlled by, or is under common control with You. For
+    purposes of this definition, "control" means (a) the power, direct
+    or indirect, to cause the direction or management of such entity,
+    whether by contract or otherwise, or (b) ownership of more than
+    fifty percent (50%) of the outstanding shares or beneficial
+    ownership of such entity.
+
+2. License Grants and Conditions
+--------------------------------
+
+2.1. Grants
+
+Each Contributor hereby grants You a world-wide, royalty-free,
+non-exclusive license:
+
+(a) under intellectual property rights (other than patent or trademark)
+    Licensable by such Contributor to use, reproduce, make available,
+    modify, display, perform, distribute, and otherwise exploit its
+    Contributions, either on an unmodified basis, with Modifications, or
+    as part of a Larger Work; and
+
+(b) under Patent Claims of such Contributor to make, use, sell, offer
+    for sale, have made, import, and otherwise transfer either its
+    Contributions or its Contributor Version.
+
+2.2. Effective Date
+
+The licenses granted in Section 2.1 with respect to any Contribution
+become effective for each Contribution on the date the Contributor first
+distributes such Contribution.
+
+2.3. Limitations on Grant Scope
+
+The licenses granted in this Section 2 are the only rights granted under
+this License. No additional rights or licenses will be implied from the
+distribution or licensing of Covered Software under this License.
+Notwithstanding Section 2.1(b) above, no patent license is granted by a
+Contributor:
+
+(a) for any code that a Contributor has removed from Covered Software;
+    or
+
+(b) for infringements caused by: (i) Your and any other third party's
+    modifications of Covered Software, or (ii) the combination of its
+    Contributions with other software (except as part of its Contributor
+    Version); or
+
+(c) under Patent Claims infringed by Covered Software in the absence of
+    its Contributions.
+
+This License does not grant any rights in the trademarks, service marks,
+or logos of any Contributor (except as may be necessary to comply with
+the notice requirements in Section 3.4).
+
+2.4. Subsequent Licenses
+
+No Contributor makes additional grants as a result of Your choice to
+distribute the Covered Software under a subsequent version of this
+License (see Section 10.2) or under the terms of a Secondary License (if
+permitted under the terms of Section 3.3).
+
+2.5. Representation
+
+Each Contributor represents that the Contributor believes its
+Contributions are its original creation(s) or it has sufficient rights
+to grant the rights to its Contributions conveyed by this License.
+
+2.6. Fair Use
+
+This License is not intended to limit any rights You have under
+applicable copyright doctrines of fair use, fair dealing, or other
+equivalents.
+
+2.7. Conditions
+
+Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted
+in Section 2.1.
+
+3. Responsibilities
+-------------------
+
+3.1. Distribution of Source Form
+
+All distribution of Covered Software in Source Code Form, including any
+Modifications that You create or to which You contribute, must be under
+the terms of this License. You must inform recipients that the Source
+Code Form of the Covered Software is governed by the terms of this
+License, and how they can obtain a copy of this License. You may not
+attempt to alter or restrict the recipients' rights in the Source Code
+Form.
+
+3.2. Distribution of Executable Form
+
+If You distribute Covered Software in Executable Form then:
+
+(a) such Covered Software must also be made available in Source Code
+    Form, as described in Section 3.1, and You must inform recipients of
+    the Executable Form how they can obtain a copy of such Source Code
+    Form by reasonable means in a timely manner, at a charge no more
+    than the cost of distribution to the recipient; and
+
+(b) You may distribute such Executable Form under the terms of this
+    License, or sublicense it under different terms, provided that the
+    license for the Executable Form does not attempt to limit or alter
+    the recipients' rights in the Source Code Form under this License.
+
+3.3. Distribution of a Larger Work
+
+You may create and distribute a Larger Work under terms of Your choice,
+provided that You also comply with the requirements of this License for
+the Covered Software. If the Larger Work is a combination of Covered
+Software with a work governed by one or more Secondary Licenses, and the
+Covered Software is not Incompatible With Secondary Licenses, this
+License permits You to additionally distribute such Covered Software
+under the terms of such Secondary License(s), so that the recipient of
+the Larger Work may, at their option, further distribute the Covered
+Software under the terms of either this License or such Secondary
+License(s).
+
+3.4. Notices
+
+You may not remove or alter the substance of any license notices
+(including copyright notices, patent notices, disclaimers of warranty,
+or limitations of liability) contained within the Source Code Form of
+the Covered Software, except that You may alter any license notices to
+the extent required to remedy known factual inaccuracies.
+
+3.5. Application of Additional Terms
+
+You may choose to offer, and to charge a fee for, warranty, support,
+indemnity or liability obligations to one or more recipients of Covered
+Software. However, You may do so only on Your own behalf, and not on
+behalf of any Contributor. You must make it absolutely clear that any
+such warranty, support, indemnity, or liability obligation is offered by
+You alone, and You hereby agree to indemnify every Contributor for any
+liability incurred by such Contributor as a result of warranty, support,
+indemnity or liability terms You offer. You may include additional
+disclaimers of warranty and limitations of liability specific to any
+jurisdiction.
+
+4. Inability to Comply Due to Statute or Regulation
+---------------------------------------------------
+
+If it is impossible for You to comply with any of the terms of this
+License with respect to some or all of the Covered Software due to
+statute, judicial order, or regulation then You must: (a) comply with
+the terms of this License to the maximum extent possible; and (b)
+describe the limitations and the code they affect. Such description must
+be placed in a text file included with all distributions of the Covered
+Software under this License. Except to the extent prohibited by statute
+or regulation, such description must be sufficiently detailed for a
+recipient of ordinary skill to be able to understand it.
+
+5. Termination
+--------------
+
+5.1. The rights granted under this License will terminate automatically
+if You fail to comply with any of its terms. However, if You become
+compliant, then the rights granted under this License from a particular
+Contributor are reinstated (a) provisionally, unless and until such
+Contributor explicitly and finally terminates Your grants, and (b) on an
+ongoing basis, if such Contributor fails to notify You of the
+non-compliance by some reasonable means prior to 60 days after You have
+come back into compliance. Moreover, Your grants from a particular
+Contributor are reinstated on an ongoing basis if such Contributor
+notifies You of the non-compliance by some reasonable means, this is the
+first time You have received notice of non-compliance with this License
+from such Contributor, and You become compliant prior to 30 days after
+Your receipt of the notice.
+
+5.2. If You initiate litigation against any entity by asserting a patent
+infringement claim (excluding declaratory judgment actions,
+counter-claims, and cross-claims) alleging that a Contributor Version
+directly or indirectly infringes any patent, then the rights granted to
+You by any and all Contributors for the Covered Software under Section
+2.1 of this License shall terminate.
+
+5.3. In the event of termination under Sections 5.1 or 5.2 above, all
+end user license agreements (excluding distributors and resellers) which
+have been validly granted by You or Your distributors under this License
+prior to termination shall survive termination.
+
+************************************************************************
+*                                                                      *
+*  6. Disclaimer of Warranty                                           *
+*  -------------------------                                           *
+*                                                                      *
+*  Covered Software is provided under this License on an "as is"       *
+*  basis, without warranty of any kind, either expressed, implied, or  *
+*  statutory, including, without limitation, warranties that the       *
+*  Covered Software is free of defects, merchantable, fit for a        *
+*  particular purpose or non-infringing. The entire risk as to the     *
+*  quality and performance of the Covered Software is with You.        *
+*  Should any Covered Software prove defective in any respect, You     *
+*  (not any Contributor) assume the cost of any necessary servicing,   *
+*  repair, or correction. This disclaimer of warranty constitutes an   *
+*  essential part of this License. No use of any Covered Software is   *
+*  authorized under this License except under this disclaimer.         *
+*                                                                      *
+************************************************************************
+
+************************************************************************
+*                                                                      *
+*  7. Limitation of Liability                                          *
+*  --------------------------                                          *
+*                                                                      *
+*  Under no circumstances and under no legal theory, whether tort      *
+*  (including negligence), contract, or otherwise, shall any           *
+*  Contributor, or anyone who distributes Covered Software as          *
+*  permitted above, be liable to You for any direct, indirect,         *
+*  special, incidental, or consequential damages of any character      *
+*  including, without limitation, damages for lost profits, loss of    *
+*  goodwill, work stoppage, computer failure or malfunction, or any    *
+*  and all other commercial damages or losses, even if such party      *
+*  shall have been informed of the possibility of such damages. This   *
+*  limitation of liability shall not apply to liability for death or   *
+*  personal injury resulting from such party's negligence to the       *
+*  extent applicable law prohibits such limitation. Some               *
+*  jurisdictions do not allow the exclusion or limitation of           *
+*  incidental or consequential damages, so this exclusion and          *
+*  limitation may not apply to You.                                    *
+*                                                                      *
+************************************************************************
+
+8. Litigation
+-------------
+
+Any litigation relating to this License may be brought only in the
+courts of a jurisdiction where the defendant maintains its principal
+place of business and such litigation shall be governed by laws of that
+jurisdiction, without reference to its conflict-of-law provisions.
+Nothing in this Section shall prevent a party's ability to bring
+cross-claims or counter-claims.
+
+9. Miscellaneous
+----------------
+
+This License represents the complete agreement concerning the subject
+matter hereof. If any provision of this License is held to be
+unenforceable, such provision shall be reformed only to the extent
+necessary to make it enforceable. Any law or regulation which provides
+that the language of a contract shall be construed against the drafter
+shall not be used to construe this License against a Contributor.
+
+10. Versions of the License
+---------------------------
+
+10.1. New Versions
+
+Mozilla Foundation is the license steward. Except as provided in Section
+10.3, no one other than the license steward has the right to modify or
+publish new versions of this License. Each version will be given a
+distinguishing version number.
+
+10.2. Effect of New Versions
+
+You may distribute the Covered Software under the terms of the version
+of the License under which You originally received the Covered Software,
+or under the terms of any subsequent version published by the license
+steward.
+
+10.3. Modified Versions
+
+If you create software not governed by this License, and you want to
+create a new license for such software, you may create and use a
+modified version of this License if you rename the license and remove
+any references to the name of the license steward (except to note that
+such modified license differs from this License).
+
+10.4. Distributing Source Code Form that is Incompatible With Secondary
+Licenses
+
+If You choose to distribute Source Code Form that is Incompatible With
+Secondary Licenses under the terms of this version of the License, the
+notice described in Exhibit B of this License must be attached.
+
+Exhibit A - Source Code Form License Notice
+-------------------------------------------
+
+  This Source Code Form is subject to the terms of the Mozilla Public
+  License, v. 2.0. If a copy of the MPL was not distributed with this
+  file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+If it is not possible or desirable to put the notice in a particular
+file, then You may include the notice in a location (such as a LICENSE
+file in a relevant directory) where a recipient would be likely to look
+for such a notice.
+
+You may add additional accurate notices of copyright ownership.
+
+Exhibit B - "Incompatible With Secondary Licenses" Notice
+---------------------------------------------------------
+
+  This Source Code Form is "Incompatible With Secondary Licenses", as
+  defined by the Mozilla Public License, v. 2.0.
diff --git a/README.md b/README.md
new file mode 100644
--- /dev/null
+++ b/README.md
@@ -0,0 +1,4 @@
+bytestring-conversion
+=====================
+
+Type-classes to convert values to and from `ByteString`.
diff --git a/Setup.hs b/Setup.hs
new file mode 100644
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/bench/Bench.hs b/bench/Bench.hs
new file mode 100644
--- /dev/null
+++ b/bench/Bench.hs
@@ -0,0 +1,62 @@
+-- This Source Code Form is subject to the terms of the Mozilla Public
+-- License, v. 2.0. If a copy of the MPL was not distributed with this
+-- file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+{-# LANGUAGE OverloadedStrings #-}
+
+module Main (main) where
+
+import Criterion
+import Criterion.Main
+import Data.ByteString.Conversion
+import Data.Int
+import Data.Monoid
+import Data.Text.Encoding (encodeUtf8)
+import Data.Word
+
+import qualified Data.ByteString.Char8 as B
+import qualified Data.Text             as T
+
+main :: IO ()
+main = defaultMain
+    [ bgroup "bytestring-to : int"
+        [ bench "1"  $ whnf toByteString (1 :: Int8)
+        , bench "2"  $ whnf toByteString (19 :: Int16)
+        , bench "4"  $ whnf toByteString (1234 :: Int32)
+        , bench "8"  $ whnf toByteString (12345678 :: Int64)
+        , bench "16" $ whnf toByteString (1234567812345678 :: Integer)
+        ]
+    , bgroup "pack . show : int"
+        [ bench "1"  $ whnf (B.pack . show) (1 :: Int8)
+        , bench "2"  $ whnf (B.pack . show) (19 :: Int16)
+        , bench "4"  $ whnf (B.pack . show) (1234 :: Int32)
+        , bench "8"  $ whnf (B.pack . show) (12345678 :: Int64)
+        , bench "16" $ whnf (B.pack . show) (1234567812345678 :: Integer)
+        ]
+    , bgroup "bytestring-to : word"
+        [ bench "1"  $ whnf toByteString (1 :: Word8)
+        , bench "2"  $ whnf toByteString (19 :: Word16)
+        , bench "4"  $ whnf toByteString (1234 :: Word32)
+        , bench "8"  $ whnf toByteString (12345678 :: Word64)
+        ]
+    , bgroup "pack . show : word"
+        [ bench "1"  $ whnf (B.pack . show) (1 :: Word8)
+        , bench "2"  $ whnf (B.pack . show) (19 :: Word16)
+        , bench "4"  $ whnf (B.pack . show) (1234 :: Word32)
+        , bench "8"  $ whnf (B.pack . show) (12345678 :: Word64)
+        ]
+    , bgroup "bytestring-to : text"
+        [ bench "26"  $ whnf toByteString txt26
+        , bench "78"  $ whnf toByteString txt78
+        ]
+    , bgroup "encodeUtf8 : txt"
+        [ bench "26"  $ whnf encodeUtf8 txt26
+        , bench "78"  $ whnf encodeUtf8 txt78
+        ]
+    ]
+
+txt26 :: T.Text
+txt26 = T.pack $ ['a' .. 'z']
+
+txt78 :: T.Text
+txt78 = txt26 <> txt26 <> txt26
diff --git a/bytestring-conversion.cabal b/bytestring-conversion.cabal
new file mode 100644
--- /dev/null
+++ b/bytestring-conversion.cabal
@@ -0,0 +1,77 @@
+name:                bytestring-conversion
+version:             0.1
+synopsis:            Type-classes to convert values to and from ByteString.
+license:             OtherLicense
+license-file:        LICENSE
+author:              Toralf Wittner
+maintainer:          Toralf Wittner <tw@dtex.org>
+copyright:           (c) 2014 Toralf Wittner
+homepage:            https://github.com/twittner/bytestring-conversion/
+bug-reports:         https://github.com/twittner/bytestring-conversion/issues
+stability:           experimental
+category:            Data
+build-type:          Simple
+cabal-version:       >= 1.10
+extra-source-files:  README.md
+
+description:
+    Defines the type-classes 'ToByteString' and 'FromByteString'
+    to convert values to and from ByteString.
+
+source-repository head
+    type:             git
+    location:         git://github.com/twittner/bytestring-conversion.git
+
+library
+    default-language: Haskell2010
+    hs-source-dirs:   src
+    ghc-options:      -Wall -O2 -fwarn-tabs -funbox-strict-fields
+    ghc-prof-options: -prof -auto-all
+
+    exposed-modules:
+        Data.ByteString.Conversion
+        Data.ByteString.Conversion.To
+        Data.ByteString.Conversion.From
+
+    other-modules:
+        Data.ByteString.Conversion.Internal
+
+    build-depends:
+        base              >= 4.5   && < 5.0
+      , attoparsec        >= 0.10  && < 0.13
+      , bytestring        >= 0.10  && < 0.11
+      , double-conversion == 2.0.*
+      , text              >= 0.11  && < 1.2
+
+test-suite bytestring-conversion-tests
+    type:             exitcode-stdio-1.0
+    default-language: Haskell2010
+    hs-source-dirs:   test
+    main-is:          Tests.hs
+    ghc-options:      -Wall -O2 -fwarn-tabs
+    ghc-prof-options: -prof -auto-all
+
+    other-modules:
+        Properties
+
+    build-depends:
+        base
+      , bytestring
+      , bytestring-conversion
+      , QuickCheck            >= 2.6
+      , tasty                 >= 0.8
+      , tasty-quickcheck      >= 0.8
+
+benchmark bytestring-conversion-bench
+    type:             exitcode-stdio-1.0
+    default-language: Haskell2010
+    main-is:          Bench.hs
+    hs-source-dirs:   bench
+    ghc-options:      -Wall -O2 -fwarn-tabs -with-rtsopts=-T
+    build-depends:
+        base
+      , bytestring
+      , bytestring-conversion
+      , criterion             >= 1.0.0.2 && < 1.1
+      , text
+      , transformers
diff --git a/src/Data/ByteString/Conversion.hs b/src/Data/ByteString/Conversion.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/ByteString/Conversion.hs
@@ -0,0 +1,23 @@
+-- This Source Code Form is subject to the terms of the Mozilla Public
+-- License, v. 2.0. If a copy of the MPL was not distributed with this
+-- file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+module Data.ByteString.Conversion
+    ( ToByteString   (..)
+    , FromByteString (..)
+    , Hex            (..)
+    , List           (..)
+
+    , toByteString
+    , toByteString'
+    , runBuilder
+
+    , fromByteString
+    , fromByteString'
+    , runParser
+    , runParser'
+    ) where
+
+import Data.ByteString.Conversion.To   as M
+import Data.ByteString.Conversion.From as M
+import Data.ByteString.Conversion.Internal
diff --git a/src/Data/ByteString/Conversion/From.hs b/src/Data/ByteString/Conversion/From.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/ByteString/Conversion/From.hs
@@ -0,0 +1,157 @@
+-- This Source Code Form is subject to the terms of the Mozilla Public
+-- License, v. 2.0. If a copy of the MPL was not distributed with this
+-- file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+module Data.ByteString.Conversion.From
+    ( FromByteString (..)
+    , fromByteString
+    , fromByteString'
+    , runParser
+    , runParser'
+    ) where
+
+import Control.Applicative
+import Control.Monad
+import Data.Attoparsec.ByteString
+import Data.Attoparsec.ByteString.Char8 (signed, decimal, double, hexadecimal)
+import Data.Bits (Bits)
+import Data.ByteString (ByteString, elem)
+import Data.ByteString.Conversion.Internal
+import Data.Int
+import Data.Maybe (isJust)
+import Data.Text (Text)
+import Data.Text.Encoding (decodeUtf8')
+import Data.Word
+import Prelude hiding (elem)
+
+import qualified Data.Attoparsec.ByteString.Lazy as Lazy
+import qualified Data.ByteString.Lazy            as Lazy
+import qualified Data.Text                       as T
+
+-- | Parse 'ByteString's.
+class FromByteString a where
+    parser :: Parser a
+
+fromByteString :: FromByteString a => ByteString -> Maybe a
+fromByteString = either (const Nothing) Just . runParser parser
+
+fromByteString' :: FromByteString a => Lazy.ByteString -> Maybe a
+fromByteString' = either (const Nothing) Just . runParser' parser
+
+runParser :: Parser a -> ByteString -> Either String a
+runParser p b = case feed (parse p b) "" of
+    Done ""   r -> Right r
+    Done _    _ -> Left "Trailing input"
+    Fail _ [] m -> Left m
+    Fail _ x  m -> Left (shows x . showString m $ "")
+    Partial _   -> Left "Unexpected result: Partial"
+
+runParser' :: Parser a -> Lazy.ByteString -> Either String a
+runParser' p b = case Lazy.parse p b of
+    Lazy.Done ""   r -> Right r
+    Lazy.Done _    _ -> Left "Trailing input"
+    Lazy.Fail _ [] m -> Left m
+    Lazy.Fail _ x  m -> Left (shows x . showString m $ "")
+
+-----------------------------------------------------------------------------
+-- Instances
+
+instance FromByteString ByteString where
+    parser = takeByteString
+
+instance FromByteString Lazy.ByteString where
+    parser = takeLazyByteString
+
+-- | A (flat) comma-separated list of values without spaces.
+instance FromByteString a => FromByteString (List a) where
+    parser = parseList
+
+-- | UTF-8 is assumed as encoding format.
+instance FromByteString Char where
+    parser = do
+        c <- text =<< takeByteString
+        if T.length c /= 1
+            then fail "Invalid Char"
+            else return $ T.head c
+
+-- | UTF-8 is assumed as encoding format.
+instance FromByteString [Char] where
+    parser = takeByteString >>= fmap T.unpack . text
+
+-- | UTF-8 is assumed as encoding format.
+instance FromByteString Text where
+    parser = takeByteString >>= text
+
+instance FromByteString Bool where
+    parser =
+        satisfy (`elem` "tT") *> string "rue"  *> pure True  <|>
+        satisfy (`elem` "fF") *> string "alse" *> pure False <|>
+        fail "Invalid Bool"
+
+instance FromByteString Double where
+    parser = signed double <|> fail "Invalid Double"
+
+instance FromByteString Integer where
+    parser = signed decimal <|> fail "Invalid Integer"
+
+instance FromByteString Int where
+    parser = signed decimal <|> fail "Invalid Int"
+
+instance FromByteString Int8 where
+    parser = signed decimal <|> fail "Invalid Int8"
+
+instance FromByteString Int16 where
+    parser = signed decimal <|> fail "Invalid Int16"
+
+instance FromByteString Int32 where
+    parser = signed decimal <|> fail "Invalid Int32"
+
+instance FromByteString Int64 where
+    parser = signed decimal <|> fail "Invalid Int64"
+
+instance FromByteString Word where
+    parser = signed decimal <|> fail "Invalid Word"
+
+instance FromByteString Word8 where
+    parser = signed decimal <|> fail "Invalid Word8"
+
+instance FromByteString Word16 where
+    parser = signed decimal <|> fail "Invalid Word16"
+
+instance FromByteString Word32 where
+    parser = signed decimal <|> fail "Invalid Word32"
+
+instance FromByteString Word64 where
+    parser = signed decimal <|> fail "Invalid Word64"
+
+instance (Integral a, Bits a) => FromByteString (Hex a) where
+    parser = Hex <$> signed (optional prefix *> hexadecimal)
+      where
+        prefix = word8 0x30 *> satisfy (`elem` "xX")
+
+-----------------------------------------------------------------------------
+-- Implementation Helpers
+
+parseList :: FromByteString a => Parser (List a)
+parseList = atEnd >>= \e ->
+    if e then return $ List []
+         else List . reverse <$> go []
+  where
+    go acc = do
+        x <- takeTill (== 0x2C)
+        v <- case runParser parser x of
+                Left  s -> fail s
+                Right a -> return a
+        c <- optional (word8 0x2C)
+        e <- atEnd
+        case (e, isJust c) of
+            (True,  True)  -> fail "trailing comma"
+            (True,  False) -> return (v:acc)
+            (False, True)  -> go (v:acc)
+            (False, False) -> fail "missing comma"
+
+text :: ByteString -> Parser Text
+text = either (fail . ("Invalid UTF-8: " ++) . show) return . decodeUtf8'
diff --git a/src/Data/ByteString/Conversion/Internal.hs b/src/Data/ByteString/Conversion/Internal.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/ByteString/Conversion/Internal.hs
@@ -0,0 +1,37 @@
+-- This Source Code Form is subject to the terms of the Mozilla Public
+-- License, v. 2.0. If a copy of the MPL was not distributed with this
+-- file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+
+module Data.ByteString.Conversion.Internal where
+
+import Control.Applicative
+import Data.Bits (Bits)
+import Text.Printf (PrintfArg)
+
+-- | Newtype wrapper to parse and produce integral numbers in
+-- hexadecimal format
+newtype Hex a = Hex { fromHex :: a }
+    deriving ( Eq
+             , Ord
+             , Num
+             , Read
+             , Show
+             , Bounded
+             , Integral
+             , Bits
+             , PrintfArg
+             , Enum
+             , Real
+             )
+
+-- | Newtype wrapper to parse and produce a comma separated list
+-- of values.
+newtype List a = List { fromList :: [a] }
+    deriving ( Eq
+             , Show
+             , Functor
+             , Applicative
+             , Monad
+             )
diff --git a/src/Data/ByteString/Conversion/To.hs b/src/Data/ByteString/Conversion/To.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/ByteString/Conversion/To.hs
@@ -0,0 +1,109 @@
+-- This Source Code Form is subject to the terms of the Mozilla Public
+-- License, v. 2.0. If a copy of the MPL was not distributed with this
+-- file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+{-# LANGUAGE BangPatterns      #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE FlexibleInstances #-}
+
+module Data.ByteString.Conversion.To
+    ( ToByteString (..)
+    , Builder
+    , toByteString
+    , toByteString'
+    , runBuilder
+    ) where
+
+import Data.ByteString (ByteString)
+import Data.ByteString.Conversion.Internal
+import Data.ByteString.Lazy.Builder
+import Data.ByteString.Lazy.Builder.Extras hiding (runBuilder)
+import Data.Double.Conversion.Text
+import Data.Int
+import Data.List (intersperse)
+import Data.Monoid
+import Data.Text (Text)
+import Data.Text.Encoding (encodeUtf8)
+import Data.Word
+import GHC.Float (float2Double)
+
+import qualified Data.ByteString.Lazy    as L
+import qualified Data.Text               as T
+import qualified Data.Text.Lazy          as TL
+import qualified Data.Text.Lazy.Encoding as TL
+
+class ToByteString a where
+    builder :: a -> Builder
+
+instance ToByteString Builder      where builder x = x
+instance ToByteString L.ByteString where builder x = lazyByteString x
+instance ToByteString ByteString   where builder x = byteString x
+instance ToByteString Text         where builder x = byteString $ encodeUtf8 x
+instance ToByteString TL.Text      where builder x = lazyByteString $ TL.encodeUtf8 x
+instance ToByteString Char         where builder x = builder $ T.singleton x
+instance ToByteString [Char]       where builder x = builder $ TL.pack x
+instance ToByteString Float        where builder x = builder $ toShortest $ float2Double x
+instance ToByteString Double       where builder x = builder $ toShortest x
+
+instance ToByteString Int          where builder x = intDec x
+instance ToByteString Int8         where builder x = int8Dec x
+instance ToByteString Int16        where builder x = int16Dec x
+instance ToByteString Int32        where builder x = int32Dec x
+instance ToByteString Int64        where builder x = int64Dec x
+instance ToByteString Integer      where builder x = integerDec x
+instance ToByteString Word         where builder x = wordDec x
+instance ToByteString Word8        where builder x = word8Dec x
+instance ToByteString Word16       where builder x = word16Dec x
+instance ToByteString Word32       where builder x = word32Dec x
+instance ToByteString Word64       where builder x = word64Dec x
+
+instance ToByteString (Hex Int)    where builder (Hex x) = sign x <> wordHex (toWord x)
+instance ToByteString (Hex Int8)   where builder (Hex x) = sign x <> word8Hex (toWord x)
+instance ToByteString (Hex Int16)  where builder (Hex x) = sign x <> word16Hex (toWord x)
+instance ToByteString (Hex Int32)  where builder (Hex x) = sign x <> word32Hex (toWord x)
+instance ToByteString (Hex Int64)  where builder (Hex x) = sign x <> word64Hex (toWord x)
+instance ToByteString (Hex Word)   where builder (Hex x) = wordHex x
+instance ToByteString (Hex Word8)  where builder (Hex x) = word8Hex x
+instance ToByteString (Hex Word16) where builder (Hex x) = word16Hex x
+instance ToByteString (Hex Word32) where builder (Hex x) = word32Hex x
+instance ToByteString (Hex Word64) where builder (Hex x) = word64Hex x
+
+instance ToByteString a => ToByteString (List a) where
+    builder = mconcat . intersperse comma . map builder . fromList
+
+instance ToByteString Bool where
+    builder True  = byteString "true"
+    builder False = byteString "false"
+
+toByteString :: ToByteString a => a -> L.ByteString
+toByteString = runBuilder . builder
+
+-- | Please note that this needs to convert from a lazy 'L.ByteString' to
+-- a strict one which involves copying the whole string.
+toByteString' :: ToByteString a => a -> ByteString
+toByteString' = L.toStrict . toByteString
+
+runBuilder :: Builder -> L.ByteString
+runBuilder = toLazyByteStringWith (safeStrategy 32 smallChunkSize) L.empty
+
+sign :: Integral a => a -> Builder
+sign n = if n < 0 then minus else mempty
+{-# SPECIALISE sign :: Int   -> Builder #-}
+{-# SPECIALISE sign :: Int8  -> Builder #-}
+{-# SPECIALISE sign :: Int16 -> Builder #-}
+{-# SPECIALISE sign :: Int32 -> Builder #-}
+{-# SPECIALISE sign :: Int64 -> Builder #-}
+
+toWord :: (Integral a, Integral b) => a -> b
+toWord = fromIntegral . abs
+{-# SPECIALISE toWord :: Int   -> Word   #-}
+{-# SPECIALISE toWord :: Int8  -> Word8  #-}
+{-# SPECIALISE toWord :: Int16 -> Word16 #-}
+{-# SPECIALISE toWord :: Int32 -> Word32 #-}
+{-# SPECIALISE toWord :: Int64 -> Word64 #-}
+
+comma, minus :: Builder
+comma = byteString ","
+minus = byteString "-"
+{-# INLINE comma #-}
+{-# INLINE minus #-}
diff --git a/test/Properties.hs b/test/Properties.hs
new file mode 100644
--- /dev/null
+++ b/test/Properties.hs
@@ -0,0 +1,115 @@
+-- This Source Code Form is subject to the terms of the Mozilla Public
+-- License, v. 2.0. If a copy of the MPL was not distributed with this
+-- file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+{-# LANGUAGE OverloadedStrings #-}
+
+module Properties (tests) where
+
+import Control.Applicative
+import Data.ByteString.Char8 (pack)
+import Data.ByteString.Conversion
+import Data.Int
+import Data.List (intercalate)
+import Data.Maybe (fromMaybe)
+import Data.Word
+import Test.QuickCheck
+import Test.Tasty
+import Test.Tasty.QuickCheck
+import Text.Printf
+
+tests :: TestTree
+tests = testGroup "Properties"
+    [ testGroup "Decimals"
+        [ testProperty "Int"    (\a -> Just (a :: Int)    == readBack a)
+        , testProperty "Int8"   (\a -> Just (a :: Int8)   == readBack a)
+        , testProperty "Int16"  (\a -> Just (a :: Int16)  == readBack a)
+        , testProperty "Int32"  (\a -> Just (a :: Int32)  == readBack a)
+        , testProperty "Int64"  (\a -> Just (a :: Int64)  == readBack a)
+        , testProperty "Word"   (\a -> Just (a :: Word)   == readBack a)
+        , testProperty "Word8 " (\a -> Just (a :: Word8)  == readBack a)
+        , testProperty "Word16" (\a -> Just (a :: Word16) == readBack a)
+        , testProperty "Word32" (\a -> Just (a :: Word32) == readBack a)
+        , testProperty "Word64" (\a -> Just (a :: Word64) == readBack a)
+        ]
+    , testGroup "Hexadecimals"
+        [ testProperty "Int"    (\a -> Just (a :: Hex Int)    == readBackHex a)
+        , testProperty "Int8"   (\a -> Just (a :: Hex Int8)   == readBackHex a)
+        , testProperty "Int16"  (\a -> Just (a :: Hex Int16)  == readBackHex a)
+        , testProperty "Int32"  (\a -> Just (a :: Hex Int32)  == readBackHex a)
+        , testProperty "Int64"  (\a -> Just (a :: Hex Int64)  == readBackHex a)
+        , testProperty "Word"   (\a -> Just (a :: Hex Word)   == readBackHex a)
+        , testProperty "Word8 " (\a -> Just (a :: Hex Word8)  == readBackHex a)
+        , testProperty "Word16" (\a -> Just (a :: Hex Word16) == readBackHex a)
+        , testProperty "Word32" (\a -> Just (a :: Hex Word32) == readBackHex a)
+        , testProperty "Word64" (\a -> Just (a :: Hex Word64) == readBackHex a)
+        ]
+    , testGroup "Bool"
+        [ testProperty "True"  readBackTrue
+        , testProperty "False" readBackFalse
+        ]
+    , testGroup "Double"
+        [ testProperty "Double" readBackDouble
+        ]
+    , testGroup "List"
+        [ testProperty "List Int"     (readCSV :: List Int -> Bool)
+        , testProperty "List Word"    (readCSV :: List Word -> Bool)
+        , testProperty "List Double"  (readCSV :: List Double -> Bool)
+        , testProperty "List Bool"    (readCSV :: List Bool -> Bool)
+        , testProperty "List Hex"     readHexCSV
+        , testProperty "Error"     readDoubleCSVAsInt
+        ]
+    ]
+
+readBack :: (Show a, FromByteString a) => a -> Maybe a
+readBack = fromByteString . pack . show
+
+readBackDouble :: Double -> Bool
+readBackDouble d = Just d == (fromByteString . pack . show $ d)
+
+readBackHex :: (PrintfArg i, Show i, FromByteString i, Integral i) => i -> Maybe i
+readBackHex = fromByteString . pack . printf "+0x%x"
+
+readBackTrue :: Property
+readBackTrue = forAll (elements ["True", "true"]) $
+    fromMaybe False . fromByteString
+
+readBackFalse :: Property
+readBackFalse = forAll (elements ["False", "false"]) $
+    fromMaybe False . fmap not . fromByteString
+
+readCSV :: (Eq a, Show a, FromByteString a) => List a -> Bool
+readCSV lst = Just lst == fromByteString (pack (csv lst))
+  where
+    csv = intercalate "," . map show . fromList
+
+readHexCSV :: List HexStr -> Bool
+readHexCSV lst =
+    let x = fromByteString (pack (csv lst))
+        y = map (snd . hex) (fromList lst)
+    in x == Just (List y)
+  where
+    csv = intercalate "," . map (fst . hex) . fromList
+
+readDoubleCSVAsInt :: List Double -> Bool
+readDoubleCSVAsInt (List []) = True
+readDoubleCSVAsInt lst       = Nothing == (fromByteString (pack (csv lst)) :: Maybe (List Int))
+  where
+    csv = intercalate "," . map show . fromList
+
+newtype HexStr = HexStr
+    { hex :: (String, Hex Int)
+    } deriving (Show)
+
+instance Arbitrary HexStr where
+    arbitrary = do
+        i <- arbitrary
+        x <- elements ['x', 'X']
+        return $ HexStr (printf ('+':'0':x:"%x") i, i)
+
+instance Arbitrary a => Arbitrary (Hex a) where
+    arbitrary = Hex <$> arbitrary
+
+instance Arbitrary a => Arbitrary (List a) where
+    arbitrary = List <$> arbitrary
+
diff --git a/test/Tests.hs b/test/Tests.hs
new file mode 100644
--- /dev/null
+++ b/test/Tests.hs
@@ -0,0 +1,12 @@
+-- This Source Code Form is subject to the terms of the Mozilla Public
+-- License, v. 2.0. If a copy of the MPL was not distributed with this
+-- file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+module Main where
+
+import Test.Tasty
+import qualified Properties
+
+main :: IO ()
+main = defaultMain $ testGroup "Tests" [Properties.tests]
+
