diff --git a/package.yaml b/package.yaml
index 21401e8..336b741 100644
--- a/package.yaml
+++ b/package.yaml
@@ -19,6 +19,7 @@ extra-source-files:
 description:         Please see the README on GitHub at <https://github.com/githubuser/scalie#readme>
 
 default-extensions:
+  - DerivingStrategies
   - ImportQualifiedPost
   - NoImplicitPrelude
   - StandaloneKindSignatures
diff --git a/scalie.cabal b/scalie.cabal
index 0aa5f28..b67faef 100644
--- a/scalie.cabal
+++ b/scalie.cabal
@@ -19,11 +19,8 @@ extra-source-files:
 
 library
   exposed-modules:
-      Control.Ord.LexicographicallySorted
       Data.Map.Implicit
-      Language.Scalie.Ast
       Language.Scalie.Ast.Definition
-      Language.Scalie.Ast.Definition.Body
       Language.Scalie.Ast.Expression
       Language.Scalie.Ast.Module
       Language.Scalie.Ast.Pattern
@@ -33,6 +30,7 @@ library
   hs-source-dirs:
       src
   default-extensions:
+      DerivingStrategies
       ImportQualifiedPost
       NoImplicitPrelude
       StandaloneKindSignatures
@@ -52,6 +50,7 @@ executable scalie-exe
   hs-source-dirs:
       app
   default-extensions:
+      DerivingStrategies
       ImportQualifiedPost
       NoImplicitPrelude
       StandaloneKindSignatures
@@ -73,6 +72,7 @@ test-suite scalie-test
   hs-source-dirs:
       test
   default-extensions:
+      DerivingStrategies
       ImportQualifiedPost
       NoImplicitPrelude
       StandaloneKindSignatures
diff --git a/src/Data/Map/Implicit.hs b/src/Data/Map/Implicit.hs
index f983432..ab2906e 100644
--- a/src/Data/Map/Implicit.hs
+++ b/src/Data/Map/Implicit.hs
@@ -1,17 +1,25 @@
 {-# LANGUAGE Safe #-}
 {-# LANGUAGE TypeFamilies #-}
---
+{-# LANGUAGE StandaloneDeriving #-} -- specify instance contexts
+{-# LANGUAGE FlexibleContexts #-} -- use non type-variable argument in instance head
+{-# LANGUAGE UndecidableInstances #-} -- use type family in instance head
 -- | A Map that derives the keys for the mapping from the items.
 
 module Data.Map.Implicit (ImplicitMap(), get, ImplicitKeyOf(..), empty) where
 import Data.Kind (Type, Constraint)
 import Data.Map (Map)
 import Data.Map qualified as Map
+import Text.Show (Show)
+import Text.Read (Read)
+import Data.Ord (Ord)
 
 type ImplicitMap :: Type -> Type
 type role ImplicitMap nominal
 newtype ImplicitMap v = ImplicitMap { get :: Map (KeyType v) v }
 
+deriving stock instance (Show (KeyType v), Show v) => Show (ImplicitMap v)
+deriving stock instance (Read (KeyType v), Ord (KeyType v), Read v) => Read (ImplicitMap v)
+
 type ImplicitKeyOf :: Type -> Constraint
 
 class ImplicitKeyOf v where
diff --git a/src/Language/Scalie/Ast/Definition.hs b/src/Language/Scalie/Ast/Definition.hs
index f7f092d..9e6d6f8 100644
--- a/src/Language/Scalie/Ast/Definition.hs
+++ b/src/Language/Scalie/Ast/Definition.hs
@@ -1,26 +1,51 @@
 {-# LANGUAGE Safe #-}
 {-# LANGUAGE InstanceSigs #-}
 {-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE StandaloneDeriving #-}
+{-# LANGUAGE UndecidableInstances #-}
 module Language.Scalie.Ast.Definition (Definition(..)) where
 
 import Data.Kind (Type)
 import Data.Text (Text)
 
-import Language.Scalie.Domain.Type qualified as Scalie.Domain
-import Language.Scalie.Ast.Definition.Body (DefinitionBody)
 import Data.Map.Implicit (ImplicitKeyOf (KeyType, keyOf))
 
+import Language.Scalie.Domain.Type qualified as Scalie.Domain
+import Language.Scalie.Ast.Expression (Expression)
+import Text.Show (Show)
+import Text.Read (Read)
+
+-- | The definition of a value or a function (which is also a value)
+--
+-- >>> import Data.Functor.Identity (Identity(Identity))
+-- >>> import Data.Function (($))
+-- >>> :set -XOverloadedStrings
+-- >>> import Language.Scalie.Ast.Expression qualified as Expression
+-- >>> Definition (Identity Scalie.Domain.RawInt) (Identity "x") (Identity (Expression.RawInt 5))
+-- Definition {signature = Identity RawInt, name = Identity "x", body = Identity (RawInt 5)}
+--
+-- >>> import Data.Maybe (Maybe(..))
+-- >>> Definition Nothing (Just "x") (Just (Expression.RawInt 5))
+-- Definition {signature = Nothing, name = Just "x", body = Just (RawInt 5)}
+--
+-- >>> import Text.Read (readMaybe)
+-- >>> readMaybe "Definition {signature = Just RawInt, name = Nothing, body = Nothing}" :: Maybe (Definition Maybe)
+-- Just (Definition {signature = Just RawInt, name = Nothing, body = Nothing})
+
 type Definition :: (Type -> Type) -> Type
 type role Definition nominal
 data Definition f = Definition
   { signature   :: f Scalie.Domain.Type
   -- ^ What is the type
   , name        :: f Text 
-  -- ^ Which name will be used to refer to this definition
-  , body        :: f (DefinitionBody f)
+  -- ^ Which name can be used to refer to this definition
+  , body        :: f Expression
   -- ^ What needs to be evaluated to get the value
   }
 
+deriving stock instance (Show (f Expression), Show (f Scalie.Domain.Type), Show (f Text)) => Show (Definition f)
+deriving stock instance (Read (f Expression), Read (f Scalie.Domain.Type), Read (f Text)) => Read (Definition f)
+
 instance ImplicitKeyOf (Definition f) where
   type KeyType (Definition f) = f Text
   keyOf :: Definition f -> KeyType (Definition f)
diff --git a/src/Language/Scalie/Ast/Definition/Body.hs b/src/Language/Scalie/Ast/Definition/Body.hs
deleted file mode 100644
index 796c022..0000000
--- a/src/Language/Scalie/Ast/Definition/Body.hs
+++ /dev/null
@@ -1,15 +0,0 @@
-{-# LANGUAGE Trustworthy #-} -- I declare trustworthiness because I only use Vector, I do not call any unsafe functions.
-module Language.Scalie.Ast.Definition.Body (DefinitionBody(..)) where
-
-import Data.Vector (Vector)
-
-import Language.Scalie.Ast.Expression (Expression)
-import Language.Scalie.Ast.Pattern (Pattern)
-import Data.Kind (Type)
-
-type DefinitionBody :: (Type -> Type) -> Type
-type role DefinitionBody representational
-data DefinitionBody f = DefinitionBody
-  { arguments :: f (Vector Pattern)
-  , rhs       :: f Expression
-  }
diff --git a/src/Language/Scalie/Ast/Expression.hs b/src/Language/Scalie/Ast/Expression.hs
index 061c94e..09ef3b3 100644
--- a/src/Language/Scalie/Ast/Expression.hs
+++ b/src/Language/Scalie/Ast/Expression.hs
@@ -3,7 +3,10 @@ module Language.Scalie.Ast.Expression (Expression(..)) where
 
 import Prelude (Integer)
 import Data.Kind (Type)
+import Text.Show (Show)
+import Text.Read (Read)
 
 type Expression :: Type
 data Expression
   = RawInt Integer
+  deriving stock (Show, Read)
diff --git a/src/Language/Scalie/Ast/Module.hs b/src/Language/Scalie/Ast/Module.hs
index ca7587f..f90f9d1 100644
--- a/src/Language/Scalie/Ast/Module.hs
+++ b/src/Language/Scalie/Ast/Module.hs
@@ -1,13 +1,27 @@
 {-# LANGUAGE Safe #-}
-{-# LANGUAGE StandaloneKindSignatures #-}
+{-# LANGUAGE StandaloneKindSignatures #-} -- because of -Weverything
+{-# LANGUAGE StandaloneDeriving #-} -- to specify contexts
+{-# LANGUAGE FlexibleContexts #-} -- 'non type-variable argument'
+{-# LANGUAGE UndecidableInstances #-} -- instance head no smaller...
 module Language.Scalie.Ast.Module (Module(..)) where
 
 import Data.Kind (Type)
 import Language.Scalie.Ast.Definition (Definition)
 import Data.Map.Implicit (ImplicitMap)
+import Text.Show ( Show )
+import Text.Read (Read)
+import Data.Text (Text)
+import Language.Scalie.Ast.Expression (Expression)
+import Language.Scalie.Domain.Type qualified as Scalie.Domain
+import Data.Ord (Ord)
+
+-- | A module groups multiple related definitions.
 
 type Module :: (Type -> Type) -> Type
 type role Module nominal
 data Module f = Module
   { definitions :: ImplicitMap (Definition f)
   }
+
+deriving stock instance (Show (f Text), Show (f Expression), Show (f Scalie.Domain.Type)) => Show (Module f)
+deriving stock instance (Read (f Text), Ord (f Text), Read (f Expression), Read (f Scalie.Domain.Type)) => Read (Module f)
diff --git a/src/Language/Scalie/Ast/Pattern.hs b/src/Language/Scalie/Ast/Pattern.hs
index 57e9ee6..9a07dc4 100644
--- a/src/Language/Scalie/Ast/Pattern.hs
+++ b/src/Language/Scalie/Ast/Pattern.hs
@@ -1,6 +1,28 @@
 {-# LANGUAGE Safe #-}
+{-# LANGUAGE DerivingStrategies #-}
 module Language.Scalie.Ast.Pattern (Pattern(..)) where
 import Prelude (Integer)
+import Text.Show (Show)
+import Text.Read (Read, readMaybe)
+import Data.Kind qualified
 
+
+-- | A pattern in scalie. Used to select branches to jump to, with pattern matching.
+--
+-- >>> RawInt 15
+-- RawInt 15
+--
+-- >>> import Data.Maybe (Maybe)
+-- >>> readMaybe "RawInt (-5)" :: Maybe Pattern
+-- Just (RawInt (-5))
+--
+-- >>> readMaybe "RawInt (+5)" :: Maybe Pattern
+-- Nothing
+--
+-- >>> readMaybe "RawInt (5)" :: Maybe Pattern
+-- Just (RawInt 5)
+type Pattern :: Data.Kind.Type
 data Pattern
   = RawInt Integer
+  deriving stock (Show, Read)
+
diff --git a/src/Language/Scalie/Domain/Type.hs b/src/Language/Scalie/Domain/Type.hs
index 757d4d2..bf54b2d 100644
--- a/src/Language/Scalie/Domain/Type.hs
+++ b/src/Language/Scalie/Domain/Type.hs
@@ -2,7 +2,11 @@
 module Language.Scalie.Domain.Type (Type(..)) where
 
 import Data.Kind qualified
+import Text.Show (Show)
+import Text.Read (Read)
 
 type Type :: Data.Kind.Type
-data Type 
+data Type
   = RawInt
+  deriving stock (Show, Read)
+