diff --git a/scalie.cabal b/scalie.cabal
index 5d04b75..bf5a427 100644
--- a/scalie.cabal
+++ b/scalie.cabal
@@ -24,11 +24,6 @@ library
       Language.Scalie.Bytecode.Object
       Language.Scalie.Bytecode.Object.Builder
       Language.Scalie.Compiler.Bytecode
-      Language.Scalie.Core.AlgebraicDatatype
-      Language.Scalie.Core.AlgebraicDatatype.Constructor
-      Language.Scalie.Core.AlgebraicDatatype.Field
-      Language.Scalie.Core.AlgebraicDatatype.FieldIdentifier
-      Language.Scalie.Core.AlgebraicDatatype.TypeName
       Language.Scalie.Core.Definition
       Language.Scalie.Core.Expression
       Language.Scalie.Core.Expression.ConstructorIdentifier
diff --git a/src/Language/Scalie/Core/AlgebraicDatatype.hs b/src/Language/Scalie/Core/AlgebraicDatatype.hs
deleted file mode 100644
index 3b001db..0000000
--- a/src/Language/Scalie/Core/AlgebraicDatatype.hs
+++ /dev/null
@@ -1,19 +0,0 @@
-{-# LANGUAGE Trustworthy #-}
-module Language.Scalie.Core.AlgebraicDatatype (AlgebraicDatatype(..)) where
-
--- meta
-import Data.Kind (Type)
-
--- data structures
-import Data.Vector (Vector)
-
--- scalie
-import Language.Scalie.Core.AlgebraicDatatype.TypeName (TypeName)
-import Language.Scalie.Core.AlgebraicDatatype.Constructor (Constructor)
-
-type AlgebraicDatatype :: (Type -> Type) -> Type
-type role AlgebraicDatatype nominal
-data AlgebraicDatatype f = AlgebraicDatatype
-  { name :: f TypeName
-  , constructors :: f (Vector (Constructor f))
-  }
diff --git a/src/Language/Scalie/Core/AlgebraicDatatype/Constructor.hs b/src/Language/Scalie/Core/AlgebraicDatatype/Constructor.hs
deleted file mode 100644
index e70144c..0000000
--- a/src/Language/Scalie/Core/AlgebraicDatatype/Constructor.hs
+++ /dev/null
@@ -1,13 +0,0 @@
-{-# LANGUAGE Trustworthy #-} -- uses vector operations
-module Language.Scalie.Core.AlgebraicDatatype.Constructor (Constructor(..)) where
-import Data.Kind (Type)
-import Language.Scalie.Core.Expression.ConstructorIdentifier (ConstructorIdentifier)
-import Data.Vector (Vector)
-import Language.Scalie.Core.AlgebraicDatatype.Field (Field)
-
-type Constructor :: (Type -> Type) -> Type
-type role Constructor nominal
-data Constructor f = Constructor
-  { name   :: f ConstructorIdentifier
-  , fields :: f (Vector (Field f))
-  }
diff --git a/src/Language/Scalie/Core/AlgebraicDatatype/Field.hs b/src/Language/Scalie/Core/AlgebraicDatatype/Field.hs
deleted file mode 100644
index 808b4b8..0000000
--- a/src/Language/Scalie/Core/AlgebraicDatatype/Field.hs
+++ /dev/null
@@ -1,16 +0,0 @@
-{-# LANGUAGE Safe #-}
-module Language.Scalie.Core.AlgebraicDatatype.Field (Field(..)) where
-
--- meta
-import Data.Kind qualified
-
--- scalie
-import Language.Scalie.Core.AlgebraicDatatype.FieldIdentifier (FieldIdentifier)
-import Language.Scalie.Domain.Type qualified as Scalie.Domain
-
-type Field :: (Data.Kind.Type -> Data.Kind.Type) -> Data.Kind.Type
-type role Field nominal
-data Field f = Field
-  { name :: f FieldIdentifier
-  , typ  :: f Scalie.Domain.Type
-  }
diff --git a/src/Language/Scalie/Core/AlgebraicDatatype/FieldIdentifier.hs b/src/Language/Scalie/Core/AlgebraicDatatype/FieldIdentifier.hs
deleted file mode 100644
index 8892208..0000000
--- a/src/Language/Scalie/Core/AlgebraicDatatype/FieldIdentifier.hs
+++ /dev/null
@@ -1,8 +0,0 @@
-{-# LANGUAGE Safe #-}
-module Language.Scalie.Core.AlgebraicDatatype.FieldIdentifier (FieldIdentifier(..)) where
-import Data.Text (Text)
-import Data.Kind (Type)
-
-type FieldIdentifier :: Type
-newtype FieldIdentifier = FieldIdentifier { get :: Text }
-  deriving stock (Show, Read, Eq)
diff --git a/src/Language/Scalie/Core/AlgebraicDatatype/TypeName.hs b/src/Language/Scalie/Core/AlgebraicDatatype/TypeName.hs
deleted file mode 100644
index 14d2667..0000000
--- a/src/Language/Scalie/Core/AlgebraicDatatype/TypeName.hs
+++ /dev/null
@@ -1,22 +0,0 @@
-{-# LANGUAGE Safe #-}
-{-# LANGUAGE InstanceSigs #-}
-module Language.Scalie.Core.AlgebraicDatatype.TypeName (TypeName(..)) where
-
--- meta
-import Data.Kind (Type)
-
--- data structures
-import Data.Text (Text)
-import Data.Text qualified as Text
-
--- library: QuickCheck
-import Test.QuickCheck (Arbitrary (arbitrary), Gen, UnicodeString (getUnicodeString))
-
-type TypeName :: Type
-newtype TypeName = TypeName { get :: Text }
-  deriving stock (Show, Read, Eq)
-
-instance Arbitrary TypeName where
-  arbitrary :: Gen TypeName
-  arbitrary = TypeName . Text.pack . getUnicodeString <$> arbitrary
-
diff --git a/src/Language/Scalie/Core/Definition.hs b/src/Language/Scalie/Core/Definition.hs
index 60e2cb8..c1f0f60 100644
--- a/src/Language/Scalie/Core/Definition.hs
+++ b/src/Language/Scalie/Core/Definition.hs
@@ -60,8 +60,6 @@ deriving stock instance (Show (f (Expression f)), Show (f Scalie.Domain.Type), S
 deriving stock instance (Read (f (Expression f)), Read (f Scalie.Domain.Type), Read (f Text)) => Read (Definition f)
 deriving stock instance (Eq   (f (Expression f)), Eq (f Scalie.Domain.Type)  , Eq (f Text))   => Eq (Definition f)
 
--- | Using custom instances allows extracting just the text whereever possible.
-
 instance ImplicitKeyOf (Definition (Provenance a)) where
   type KeyType (Definition (Provenance a)) = Text
   keyOf :: Definition (Provenance a) -> KeyType (Definition (Provenance a))
diff --git a/src/Language/Scalie/Core/Expression.hs b/src/Language/Scalie/Core/Expression.hs
index 6511fb7..3c84c15 100644
--- a/src/Language/Scalie/Core/Expression.hs
+++ b/src/Language/Scalie/Core/Expression.hs
@@ -24,8 +24,6 @@ import Test.QuickCheck.Gen (Gen)
 import Test.QuickCheck qualified as Gen
 
 
--- | Desugared expression.
-
 type Expression :: (Type -> Type) -> Type
 type role Expression nominal
 data Expression f
diff --git a/src/Language/Scalie/Core/Module.hs b/src/Language/Scalie/Core/Module.hs
index 6266529..0a0ce69 100644
--- a/src/Language/Scalie/Core/Module.hs
+++ b/src/Language/Scalie/Core/Module.hs
@@ -5,24 +5,33 @@
 {-# LANGUAGE UndecidableInstances #-} -- instance head no smaller...
 module Language.Scalie.Core.Module (Module(..)) where
 
--- meta
 import Data.Kind (Type)
-
--- data types
+import Language.Scalie.Core.Definition (Definition)
 import Data.Map.Implicit (ImplicitMap)
 
--- scalie
-import Language.Scalie.Core.Definition (Definition)
-import safe Language.Scalie.Core.AlgebraicDatatype ( AlgebraicDatatype )
-
--- | A module groups multiple related variable definitions.
+-- | A module groups multiple related definitions.
+--
+-- >>> import Data.Functor.Identity (Identity(..))
+-- >>> import Data.Map.Implicit qualified as ImplicitMap
+-- >>> Module (Identity ImplicitMap.empty)
+-- Module {definitions = Identity ImplicitMapElems []}
+--
+-- >>> import Data.Maybe (Maybe(..))
+-- >>> Module Nothing
+-- Module {definitions = Nothing}
+--
+-- >>> import Text.Read (readMaybe)
+-- >>> readMaybe "Module { definitions = Just (ImplicitMapElems []) }" :: Maybe (Module Maybe)
+-- Just (Module {definitions = Just ImplicitMapElems []})
+--
+-- >>> readMaybe "Module { definitions = Just (ImplicitMapElems [Definition { signature = Nothing, name = Just \"x\", body = Nothing } ]) }" :: Maybe (Module Maybe)
+-- Just (Module {definitions = Just ImplicitMapElems [Definition {signature = Nothing, name = Just "x", body = Nothing}]})
 
 type Module :: (Type -> Type) -> Type
 type role Module nominal
-data Module f = Module
+newtype Module f = Module
   { definitions :: f (ImplicitMap (Definition f))
-  , datatypes   :: f (ImplicitMap (AlgebraicDatatype f))
   }
 
-deriving stock instance (Show (f (ImplicitMap (Definition f))), Show (f (ImplicitMap (AlgebraicDatatype f)))) => Show (Module f)
-deriving stock instance (Read (f (ImplicitMap (Definition f))), Read (f (ImplicitMap (AlgebraicDatatype f)))) => Read (Module f)
+deriving stock instance (Show (f (ImplicitMap (Definition f)))) => Show (Module f)
+deriving stock instance (Read (f (ImplicitMap (Definition f)))) => Read (Module f)
diff --git a/src/Language/Scalie/Core/Provenance.hs b/src/Language/Scalie/Core/Provenance.hs
index 50714c7..d067c69 100644
--- a/src/Language/Scalie/Core/Provenance.hs
+++ b/src/Language/Scalie/Core/Provenance.hs
@@ -11,8 +11,6 @@ import Data.Bifunctor (Bifunctor (bimap))
 import Data.Bifoldable (Bifoldable (bifoldMap))
 import Data.Bitraversable (Bitraversable (bitraverse))
 
--- | Provenance records where something comes from. E.g. file name, file line, other sources.
-
 type Provenance :: Type -> Type -> Type
 type role Provenance representational representational 
 data Provenance source value = Provenance
diff --git a/src/Language/Scalie/Core/Provenance/SourceLocation.hs b/src/Language/Scalie/Core/Provenance/SourceLocation.hs
index 3ecf436..ab1f76f 100644
--- a/src/Language/Scalie/Core/Provenance/SourceLocation.hs
+++ b/src/Language/Scalie/Core/Provenance/SourceLocation.hs
@@ -1,10 +1,9 @@
 {-# LANGUAGE Safe #-}
 module Language.Scalie.Core.Provenance.SourceLocation (SourceLocation(..)) where
 import Data.Kind (Type)
-
--- | Location of anything in a user-provided source file.
---
--- TODO: Add more constructors
+import Text.Show (Show)
+import Text.Read (Read)
+import Data.Eq (Eq)
 
 type SourceLocation :: Type
 data SourceLocation
diff --git a/src/Language/Scalie/Domain/Type.hs b/src/Language/Scalie/Domain/Type.hs
index 97354de..92f9f87 100644
--- a/src/Language/Scalie/Domain/Type.hs
+++ b/src/Language/Scalie/Domain/Type.hs
@@ -3,17 +3,17 @@
 module Language.Scalie.Domain.Type (Type(..)) where
 
 import Data.Kind qualified
+import Text.Show (Show)
+import Text.Read (Read)
+import Data.Eq (Eq)
 import Test.QuickCheck (Arbitrary (arbitrary), Gen, oneof)
-
--- | The type of an expression in Scalie, not to be confused with the 'Type' provided by GHC
+import Control.Applicative (Applicative(pure))
 
 type Type :: Data.Kind.Type
 data Type
   = RawInt
   deriving stock (Show, Read, Eq)
 
-  -- add to the arbitrary instance when defining constructors
-
 instance Arbitrary Type where
   arbitrary :: Gen Type
   arbitrary = oneof [ pure RawInt ]