Parser: support tilde in paths

src/Nix/Exec.hs

@@ -290,7 +290,8 @@ instance (MonadFix m, MonadCatch m, MonadThrow m, MonadIO m)
           _ -> throwError $ "addPath: failed: nix-store --add " ++ show path
 
     makeAbsolutePath origPath = do
-        absPath <- if isAbsolute origPath then pure origPath else do
+        origPathExpanded <- liftIO $ expandHomePath origPath
+        absPath <- if isAbsolute origPathExpanded then pure origPathExpanded else do
             cwd <- do
                 mres <- lookupVar @_ @(NThunk (Lazy m)) "__cur_file"
                 case mres of
@@ -301,7 +302,8 @@ instance (MonadFix m, MonadCatch m, MonadThrow m, MonadIO m)
                                 ++ " __cur_file is in scope,"
                                 ++ " but is not a path; it is: "
                                 ++ show v
-            pure $ cwd <///> origPath
+            pure $ cwd <///> origPathExpanded
+        _ <- liftIO $ putStrLn $ show absPath
         liftIO $ removeDotDotIndirections <$> canonicalizePath absPath
 
     findEnvPath = findEnvPathM
@@ -418,6 +420,10 @@ removeDotDotIndirections = intercalate "/" . go [] . splitOn "/"
           go (_:s) ("..":rest) = go s rest
           go s (this:rest) = go (this:s) rest
 
+expandHomePath :: FilePath -> IO FilePath
+expandHomePath ('~' : xs) = flip (++) xs <$> getHomeDirectory
+expandHomePath p = return p
+
 -- Given a path, determine the nix file to load
 pathToDefaultNixFile :: FilePath -> IO FilePath
 pathToDefaultNixFile p = do

src/Nix/Parser.hs

@@ -126,7 +126,7 @@ nixList :: Parser NExprLoc
 nixList = annotateLocation1 (brackets (NList <$> many nixTerm) <?> "list")
 
 pathChar :: Char -> Bool
-pathChar x = isAlpha x || isDigit x || x == '.' || x == '_' || x == '-' || x == '+'
+pathChar x = isAlpha x || isDigit x || x == '.' || x == '_' || x == '-' || x == '+' || x == '~'
 
 slash :: Parser Char
 slash = try (char '/' <* notFollowedBy (satisfy (\x -> x == '/' || x == '*' || isSpace x)))

tests/ParserTests.hs

@@ -53,6 +53,10 @@ case_constant_path = do
   assertParseFail "/"
   assertParseFail "a/"
   assertParseFail "a/def/"
+  assertParseFail "~"
+  assertParseFail "~/"
+  assertParseText "~/a" $ mkPath False "~/a"
+  assertParseText "~/a/b" $ mkPath False "~/a/b"
 
 case_constant_uri = do
   assertParseText "a:a" $ mkUri "a:a"