Value: TStringContext: add instances {Semigroup, Monoid}

Author: Anton-Latukha

src/Nix/Convert.hs

@@ -205,19 +205,18 @@ instance ( Convertible e t f m
           (M.lookup "outPath" s)
       _ -> stub
 
-  fromValue = fromMayToValue $ TString NoContext
+  fromValue = fromMayToValue $ TString mempty
 
 instance Convertible e t f m
   => FromValue ByteString m (NValue' t f m (NValue t f m)) where
 
   fromValueMay =
     pure .
       \case
-        NVStr' ns -> encodeUtf8 <$> getStringNoContext  ns
+        NVStr' ns -> encodeUtf8 <$> getStringNoContext ns
         _         -> mempty
 
-  fromValue = fromMayToValue $ TString NoContext
-
+  fromValue = fromMayToValue $ TString mempty
 
 newtype Path = Path FilePath
     deriving Show
@@ -229,8 +228,8 @@ instance ( Convertible e t f m
 
   fromValueMay =
     \case
-      NVPath' p  -> pure $ pure $ Path p
-      NVStr'  ns -> pure $ Path . toString <$> getStringNoContext  ns
+      NVPath' p  -> pure $ pure $ coerce p
+      NVStr'  ns -> pure $ coerce . toString <$> getStringNoContext  ns
       NVSet' s _ ->
         maybe
           (pure Nothing)

src/Nix/String/Coerce.hs

@@ -116,5 +116,5 @@ coerceToString call ctsm clevel = go
       t
       (StringContext t DirectPath)
    where
-    t = toText $ unStorePath sp
+    t = toText @FilePath $ coerce sp
 

src/Nix/Value.hs

@@ -706,6 +706,15 @@ pattern NVBuiltin name f <- Free (NVBuiltin' name f)
 data TStringContext = NoContext | HasContext
   deriving Show
 
+instance Semigroup TStringContext where
+  (<>) HasContext _ = HasContext
+  (<>) _ HasContext = HasContext
+  (<>) _          _ = NoContext
+
+
+instance Monoid TStringContext where
+  mempty = NoContext
+
 -- * @ValueType@
 
 data ValueType
@@ -728,15 +737,15 @@ valueType =
   \case
     NVConstantF a ->
       case a of
-        NURI   _ -> TString NoContext
+        NURI   _ -> TString mempty
         NInt   _ -> TInt
         NFloat _ -> TFloat
         NBool  _ -> TBool
         NNull    -> TNull
     NVStrF ns  ->
       TString $
         bool
-          NoContext
+          mempty
           HasContext
           (stringHasContext ns)
     NVListF{}    -> TList