diff --git a/library/THLego/Instances.hs b/library/THLego/Instances.hs
--- a/library/THLego/Instances.hs
+++ b/library/THLego/Instances.hs
@@ -115,9 +115,21 @@
       FunD 'getField getFieldFunClauses
 
 {-|
-Field which projects enum values into bools.
+'HasField' instance which focuses on a variant of an enum
+and projects it into 'Bool' signaling whether the value matches.
+
+Generates code of the following pattern:
+
+> instance HasField "fieldLabel" enumType Bool
 -}
-enumHasField :: TyLit -> Type -> Name -> Dec
+enumHasField ::
+  {-| Field label. -}
+  TyLit ->
+  {-| Enum type. -}
+  Type ->
+  {-| Name of the constructor. -}
+  Name ->
+  Dec
 enumHasField fieldLabel ownerType constructorName =
   hasField fieldLabel ownerType projectionType getFieldFunClauses
   where
@@ -137,7 +149,28 @@
             bodyExp =
               ConE 'False
 
-sumHasField :: TyLit -> Type -> Name -> [Type] -> Dec
+{-|
+Instance of 'HasField' for a constructor of a sum ADT,
+projecting it into a 'Maybe' tuple of its members.
+
+Generates code of the following pattern:
+
+> instance HasField "fieldLabel" sumAdt (Maybe projectionType)
+
+- When the amount of member types is 0, @projectionType@ is @()@.
+- When the amount of member types is 1, it is that member type.
+- Otherwise it is a tuple of those members.
+-}
+sumHasField ::
+  {-| Field label. -}
+  TyLit ->
+  {-| The ADT type. -}
+  Type ->
+  {-| Name of the constructor. -}
+  Name ->
+  {-| Member types of that constructor. -}
+  [Type] ->
+  Dec
 sumHasField fieldLabel ownerType constructorName memberTypes =
   hasField fieldLabel ownerType projectionType getFieldFunClauses
   where
@@ -162,7 +195,23 @@
             bodyExp =
               ConE 'Nothing
 
-productHasField :: TyLit -> Type -> Type -> Name -> Int -> Int -> Dec
+{-|
+Instance of 'HasField' for a member of a product type.
+-}
+productHasField ::
+  {-| Field label. -}
+  TyLit ->
+  {-| Type of the product. -}
+  Type ->
+  {-| Type of the member we're focusing on. -}
+  Type ->
+  {-| Constructor name. -}
+  Name ->
+  {-| Total amount of members in the product. -}
+  Int ->
+  {-| Offset of the member we're focusing on. -}
+  Int ->
+  Dec
 productHasField fieldLabel ownerType projectionType constructorName totalMemberTypes offset =
   hasField fieldLabel ownerType projectionType getFieldFunClauses
   where
diff --git a/library/THLego/Lambdas.hs b/library/THLego/Lambdas.hs
--- a/library/THLego/Lambdas.hs
+++ b/library/THLego/Lambdas.hs
@@ -17,7 +17,19 @@
 {-|
 Lambda expression, which extracts a product member by index.
 -}
-productGetter :: Name -> Int -> Int -> Exp
+productGetter ::
+  {-| Constructor name. -}
+  Name ->
+  {-| Total amount of members. -}
+  Int ->
+  {-| Index of the member. -}
+  Int ->
+  {-|
+  Lambda expression of the following form:
+  
+  > product -> member
+  -}
+  Exp
 productGetter conName numMembers index =
   LamE [pat] exp
   where
@@ -36,7 +48,19 @@
 {-|
 Lambda expression, which sets a product member by index.
 -}
-productSetter :: Name -> Int -> Int -> Exp
+productSetter ::
+  {-| Constructor name. -}
+  Name ->
+  {-| Total amount of members. -}
+  Int ->
+  {-| Index of the member. -}
+  Int ->
+  {-|
+  Lambda expression of the following form:
+
+  > product -> member -> product
+  -}
+  Exp
 productSetter conName numMembers index =
   LamE [stateP, valP] exp
   where
diff --git a/th-lego.cabal b/th-lego.cabal
--- a/th-lego.cabal
+++ b/th-lego.cabal
@@ -1,6 +1,11 @@
 name: th-lego
-version: 0.1.0.2
+version: 0.1.0.3
 synopsis: Template Haskell construction utilities
+description:
+  A collection of templates for the typical patterns appearing
+  in construction of Template Haskell AST.
+  E.g., typical instance declaration templates,
+  lambda expressions for accessing members of data-types.
 stability: Experimental
 category: Template Haskell
 homepage: https://github.com/nikita-volkov/th-lego