diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,22 @@
+Copyright (c) 2020 Nikita Volkov
+
+Permission is hereby granted, free of charge, to any person
+obtaining a copy of this software and associated documentation
+files (the "Software"), to deal in the Software without
+restriction, including without limitation the rights to use,
+copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
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/domain-core.cabal b/domain-core.cabal
new file mode 100644
--- /dev/null
+++ b/domain-core.cabal
@@ -0,0 +1,38 @@
+name: domain-core
+version: 0.1
+synopsis: Low-level API of "domain"
+description:
+  Use this package for defining extensions to \"domain\".
+  Primarily derivers.
+homepage: https://github.com/nikita-volkov/domain-core
+bug-reports: https://github.com/nikita-volkov/domain-core/issues
+author: Nikita Volkov <nikita.y.volkov@mail.ru>
+maintainer: Nikita Volkov <nikita.y.volkov@mail.ru>
+copyright: (c) 2020 Nikita Volkov
+license: MIT
+license-file: LICENSE
+build-type: Simple
+cabal-version: >=1.10
+
+source-repository head
+  type: git
+  location: git://github.com/nikita-volkov/domain-core.git
+
+library
+  hs-source-dirs: library
+  default-extensions: BangPatterns, BlockArguments, ConstraintKinds, DataKinds, DefaultSignatures, DeriveDataTypeable, DeriveFoldable, DeriveFunctor, DeriveGeneric, DeriveLift, DerivingVia, DeriveTraversable, EmptyDataDecls, FlexibleContexts, FlexibleInstances, FunctionalDependencies, GADTs, GeneralizedNewtypeDeriving, InstanceSigs, LambdaCase, LiberalTypeSynonyms, MagicHash, MultiParamTypeClasses, MultiWayIf, NoImplicitPrelude, NoMonomorphismRestriction, OverloadedLabels, OverloadedStrings, PatternGuards, ParallelListComp, QuasiQuotes, RankNTypes, RecordWildCards, ScopedTypeVariables, StandaloneDeriving, StrictData, TemplateHaskell, TupleSections, TypeApplications, TypeFamilies, TypeOperators
+  default-language: Haskell2010
+  exposed-modules:
+    DomainCore.Deriver
+    DomainCore.Model
+    DomainCore.TH
+  other-modules:
+    DomainCore.Prelude
+    DomainCore.Text
+  build-depends:
+    base >=4.12 && <5,
+    text >=1 && <2,
+    template-haskell >=2.13 && <3,
+    template-haskell-compat-v0208 >=0.1.5 && <0.2,
+    th-lego >=0.2.3 && <0.3,
+    th-lift-instances >=0.1.17 && <0.2
diff --git a/library/DomainCore/Deriver.hs b/library/DomainCore/Deriver.hs
new file mode 100644
--- /dev/null
+++ b/library/DomainCore/Deriver.hs
@@ -0,0 +1,36 @@
+{-|
+Toolkit for definition of instance derivers for Domain specs.
+-}
+module DomainCore.Deriver
+(
+  -- * Deriver definitions
+  Deriver(..),
+  effectless,
+)
+where
+
+import DomainCore.Prelude
+import DomainCore.Model
+import qualified Language.Haskell.TH as TH (Q, Dec)
+
+
+{-|
+Specification of which instances to automatically derive for all the
+supported types in the model and how.
+
+You can combine derivers using Monoid and Semigroup.
+-}
+newtype Deriver =
+  {-|
+  Function from the type declaration in this package\'s own AST
+  to a list of Template Haskell declarations in its quotation monad.
+  -}
+  Deriver (TypeDec -> TH.Q [TH.Dec])
+  deriving (Semigroup, Monoid)
+    via ((->) TypeDec (Ap TH.Q [TH.Dec]))
+
+{-|
+Lift a pure function, which doesn't require the context of 'TH.Q'.
+-}
+effectless f =
+  Deriver (pure . f)
diff --git a/library/DomainCore/Model.hs b/library/DomainCore/Model.hs
new file mode 100644
--- /dev/null
+++ b/library/DomainCore/Model.hs
@@ -0,0 +1,59 @@
+{-|
+High-level model of schema.
+-}
+module DomainCore.Model
+where
+
+import DomainCore.Prelude
+
+
+{-|
+Declaration of a type.
+-}
+data TypeDec =
+  {-|
+  Name of the type and its definition.
+  -}
+  TypeDec Text TypeDef
+  deriving (Generic, Show, Eq, Ord, Lift)
+
+{-|
+Definition of a type.
+-}
+data TypeDef =
+  {-|
+  Sum.
+  A list of pairs of names of its members
+  (which will be mapped to constructors) and
+  types which will populate the according constructors.
+  -}
+  SumTypeDef [(Text, [Type])] |
+  {-|
+  Product.
+  Think of it as a record.
+  Carries a list of associations of field names with types.
+  -}
+  ProductTypeDef [(Text, Type)] 
+  deriving (Generic, Show, Eq, Ord, Lift)
+
+{-|
+Type.
+-}
+data Type =
+  {-|
+  Fully applied tuple of the listed types.
+  -}
+  TupleType [Type] |
+  {-|
+  List of type applications.
+  -}
+  AppType (NonEmpty Type) |
+  {-|
+  List type with the type of its element.
+  -}
+  ListType Type |
+  {-|
+  Possibly qualified reference to another type.
+  -}
+  RefType Text
+  deriving (Generic, Show, Eq, Ord, Lift)
diff --git a/library/DomainCore/Prelude.hs b/library/DomainCore/Prelude.hs
new file mode 100644
--- /dev/null
+++ b/library/DomainCore/Prelude.hs
@@ -0,0 +1,93 @@
+module DomainCore.Prelude
+( 
+  module Exports,
+  showAsText,
+)
+where
+
+-- base
+-------------------------
+import Control.Applicative as Exports hiding (WrappedArrow(..))
+import Control.Arrow as Exports hiding (first, second)
+import Control.Category as Exports
+import Control.Concurrent as Exports
+import Control.Exception as Exports
+import Control.Monad as Exports hiding (fail, mapM_, sequence_, forM_, msum, mapM, sequence, forM)
+import Control.Monad.IO.Class as Exports
+import Control.Monad.Fail as Exports
+import Control.Monad.Fix as Exports hiding (fix)
+import Control.Monad.ST as Exports
+import Data.Bifunctor as Exports
+import Data.Bits as Exports
+import Data.Bool as Exports
+import Data.Char as Exports
+import Data.Coerce as Exports
+import Data.Complex as Exports
+import Data.Data as Exports
+import Data.Dynamic as Exports
+import Data.Either as Exports
+import Data.Fixed as Exports
+import Data.Foldable as Exports hiding (toList)
+import Data.Function as Exports hiding (id, (.))
+import Data.Functor as Exports
+import Data.Functor.Compose as Exports
+import Data.Functor.Contravariant as Exports
+import Data.Int as Exports
+import Data.IORef as Exports
+import Data.Ix as Exports
+import Data.List as Exports hiding (sortOn, isSubsequenceOf, uncons, concat, foldr, foldl1, maximum, minimum, product, sum, all, and, any, concatMap, elem, foldl, foldr1, notElem, or, find, maximumBy, minimumBy, mapAccumL, mapAccumR, foldl')
+import Data.List.NonEmpty as Exports (NonEmpty(..))
+import Data.Maybe as Exports
+import Data.Monoid as Exports hiding (Alt)
+import Data.Ord as Exports
+import Data.Proxy as Exports
+import Data.Ratio as Exports
+import Data.STRef as Exports
+import Data.String as Exports
+import Data.Traversable as Exports
+import Data.Tuple as Exports
+import Data.Unique as Exports
+import Data.Version as Exports
+import Data.Void as Exports
+import Data.Word as Exports
+import Debug.Trace as Exports
+import Foreign.ForeignPtr as Exports
+import Foreign.Ptr as Exports
+import Foreign.StablePtr as Exports
+import Foreign.Storable as Exports
+import GHC.Conc as Exports hiding (orElse, withMVar, threadWaitWriteSTM, threadWaitWrite, threadWaitReadSTM, threadWaitRead)
+import GHC.Exts as Exports (IsList(..), lazy, inline, sortWith, groupWith)
+import GHC.Generics as Exports (Generic)
+import GHC.IO.Exception as Exports
+import GHC.OverloadedLabels as Exports
+import GHC.Records as Exports
+import Numeric as Exports
+import Prelude as Exports hiding (fail, concat, foldr, mapM_, sequence_, foldl1, maximum, minimum, product, sum, all, and, any, concatMap, elem, foldl, foldr1, notElem, or, mapM, sequence, id, (.))
+import System.Environment as Exports
+import System.Exit as Exports
+import System.IO as Exports (Handle, hClose)
+import System.IO.Error as Exports
+import System.IO.Unsafe as Exports
+import System.Mem as Exports
+import System.Mem.StableName as Exports
+import System.Timeout as Exports
+import Text.ParserCombinators.ReadP as Exports (ReadP, ReadS, readP_to_S, readS_to_P)
+import Text.ParserCombinators.ReadPrec as Exports (ReadPrec, readPrec_to_P, readP_to_Prec, readPrec_to_S, readS_to_Prec)
+import Text.Printf as Exports (printf, hPrintf)
+import Text.Read as Exports (Read(..), readMaybe, readEither)
+import Unsafe.Coerce as Exports
+
+-- text
+-------------------------
+import Data.Text as Exports (Text)
+
+-- template-haskell
+-------------------------
+import Language.Haskell.TH.Syntax as Exports (Lift)
+
+-- th-lift-instances
+-------------------------
+import Instances.TH.Lift as Exports ()
+
+showAsText :: Show a => a -> Text
+showAsText = show >>> fromString
diff --git a/library/DomainCore/TH.hs b/library/DomainCore/TH.hs
new file mode 100644
--- /dev/null
+++ b/library/DomainCore/TH.hs
@@ -0,0 +1,60 @@
+module DomainCore.TH
+where
+
+import DomainCore.Prelude
+import DomainCore.Model
+import qualified Language.Haskell.TH as TH
+import qualified THLego.Helpers as TH
+import qualified DomainCore.Text as Text
+import qualified Data.Text as Text
+import qualified Data.Char as Char
+
+
+{-|
+Convert a model type definition into Template Haskell.
+-}
+typeType ::
+  {-| Model type. -}
+  Type ->
+  {-| Template Haskell type. -}
+  TH.Type
+typeType =
+  \ case
+    AppType a ->
+      foldl1 TH.AppT (fmap typeType a)
+    RefType a ->
+      TH.ConT (TH.textName a)
+    ListType a ->
+      TH.AppT TH.ListT (typeType a)
+    TupleType a ->
+      TH.multiAppT (TH.TupleT (length a)) (fmap typeType a)
+
+{-|
+Assemble a record field name.
+-}
+recordFieldName ::
+  {-| Prepend with underscore. -}
+  Bool ->
+  {-| Prefix with type name. -}
+  Bool ->
+  {-| Type name. -}
+  Text ->
+  {-| Label. -}
+  Text ->
+  {-| Template Haskell name. -}
+  TH.Name
+recordFieldName underscore prefixWithTypeName a b =
+  TH.textName (Text.recordField underscore prefixWithTypeName a b)
+
+{-|
+Assemble a sum constructor name.
+-}
+sumConstructorName ::
+  {-| Type name. -}
+  Text ->
+  {-| Label. -}
+  Text ->
+  {-| Template Haskell name. -}
+  TH.Name
+sumConstructorName a b =
+  TH.textName (Text.sumConstructor a b)
diff --git a/library/DomainCore/Text.hs b/library/DomainCore/Text.hs
new file mode 100644
--- /dev/null
+++ b/library/DomainCore/Text.hs
@@ -0,0 +1,24 @@
+module DomainCore.Text
+where
+
+import DomainCore.Prelude
+import Data.Text
+import qualified Data.Char as Char
+
+
+recordField underscore prefixWithTypeName a b =
+  bool mempty "_" underscore <>
+  bool b (lcFirst a <> ucFirst b) prefixWithTypeName
+
+sumConstructor a b =
+  ucFirst b <> a
+
+mapFirstChar fn =
+  foldMap (\ (a, b) -> cons (fn a) b) .
+  uncons
+
+ucFirst =
+  mapFirstChar Char.toUpper
+
+lcFirst =
+  mapFirstChar Char.toLower