style fixes

haskell-experiments/src/Datalog/NaiveDatabase.hs

@@ -2,7 +2,6 @@
 {-# LANGUAGE ImportQualifiedPost #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE TypeApplications #-}
 {-# OPTIONS_GHC -Wno-unrecognised-pragmas #-}
 
 module Datalog.NaiveDatabase where
@@ -70,7 +69,7 @@ withFacts facts =
  where
   extractFact :: Text -> Literal
   extractFact factText =
-    case (parseDatalog factText) of
+    case parseDatalog factText of
       Right (Fact fact) -> fact
       Right otherStatement -> throw $ NonFactException factText otherStatement
       Left ex -> throw $ CannotParseStatementException factText ex
@@ -88,8 +87,7 @@ lookupRelation relationName relationMap newArity tuples =
   case Map.lookup relationName relationMap of
     Nothing -> Relation relationName newArity tuples []
     Just relation ->
-      if (_arity relation == newArity)
-        then
+      if _arity relation == newArity then
           let newTuples = Set.union tuples $ _tuples relation
            in Relation relationName newArity newTuples []
         else throw $ BadArityException relationName newArity
@@ -117,8 +115,8 @@ maybeConstant (RuleElementConstant constant) = Just constant
 maybeConstant _ = Nothing
 
 withFactsAndRules :: [Text] -> [Text] -> NaiveDatabase
-withFactsAndRules facts rules =
-  foldr addRule (withFacts facts) (extractRule <$> rules)
+withFactsAndRules facts =
+  foldr (addRule . extractRule) (withFacts facts)
  where
   extractRule :: Text -> (Literal, [Literal])
   extractRule ruleText =
@@ -139,7 +137,7 @@ withFactsAndRules facts rules =
     relationMap' = Map.insert relationName relation relationMap
     extraVariables = toElement <$> terms
     variables' = nub extraVariables
-    extraConstants = catMaybes $ maybeConstant <$> variables'
+    extraConstants = mapMaybe maybeConstant variables'
     constants' = Set.union (constants db) $ Set.fromList extraConstants
   digestBody :: RuleContext -> Literal -> RuleContext
   digestBody context (Literal neg subRelationName terms) =