Allow passing --impure flag to Nix

Closes #40

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Unreleased
 
 * feat: Improved help text.
+* feat: Allow passing '--impure' flag to Nix (issue: [@40][]) 
 * fix: Use -O1 instead of -O2 to save on compile times.
 
 ## 0.2.1 - 2022-10-24:

src/NixTree/Main.hs

@@ -20,7 +20,8 @@ version = VERSION_nix_tree
 data Opts = Opts
   { oInstallables :: [Installable],
     oVersion :: Bool,
-    oDerivation :: Bool
+    oDerivation :: Bool,
+    oImpure :: Bool
   }
 
 optsParser :: Opts.ParserInfo Opts
@@ -48,6 +49,7 @@ optsParser =
           )
         <*> Opts.switch (Opts.long "version" <> Opts.help "Show the nix-tree version")
         <*> Opts.switch (Opts.long "derivation" <> Opts.help "Operate on the store derivation rather than its outputs")
+        <*> Opts.switch (Opts.long "impure" <> Opts.help "Allow access to mutable paths and repositories")
 
     keybindingsHelp :: Opts.Doc
     keybindingsHelp =
@@ -85,7 +87,13 @@ main = do
         [] -> showAndFail "No store path given."
         p : ps -> return . fmap (Installable . toText) $ p :| ps
 
-  withStoreEnv (opts & oDerivation) installables $ \env' -> do
+  let seo =
+        StoreEnvOptions
+          { seoIsDerivation = opts & oDerivation,
+            seoIsImpure = opts & oImpure
+          }
+
+  withStoreEnv seo installables $ \env' -> do
     let env = calculatePathStats env'
         allPaths = seAll env
 

src/NixTree/StorePath.hs

@@ -7,6 +7,7 @@ module NixTree.StorePath
     StorePath (..),
     Installable (..),
     StoreEnv (..),
+    StoreEnvOptions (..),
     withStoreEnv,
     seLookup,
     seAll,
@@ -138,7 +139,8 @@ newtype Installable = Installable {installableToText :: Text}
 
 data PathInfoOptions = PathInfoOptions
   { pioIsRecursive :: Bool,
-    pioIsDerivation :: Bool
+    pioIsDerivation :: Bool,
+    pioIsImpure :: Bool
   }
 
 getPathInfo :: NixStore -> NixVersion -> PathInfoOptions -> NonEmpty Installable -> IO (NonEmpty (StorePath s (StoreName s) ()))
@@ -149,6 +151,7 @@ getPathInfo nixStore nixVersion options names = do
         ( proc
             "nix"
             ( ["path-info", "--json"]
+                ++ (if options & pioIsImpure then ["--impure"] else [])
                 ++ (if options & pioIsRecursive then ["--recursive"] else [])
                 ++ (if (options & pioIsDerivation) && nixVersion >= Nix2_4 then ["--derivation"] else [])
                 ++ (if nixVersion >= Nix2_4 then ["--extra-experimental-features", "nix-command flakes"] else [])
@@ -189,20 +192,25 @@ data StoreEnv s payload = StoreEnv
   }
   deriving (Functor, Generic, NFData)
 
+data StoreEnvOptions = StoreEnvOptions
+  { seoIsDerivation :: Bool,
+    seoIsImpure :: Bool
+  }
+
 withStoreEnv ::
   forall m a.
   MonadIO m =>
-  Bool ->
+  StoreEnvOptions ->
   NonEmpty Installable ->
   (forall s. StoreEnv s () -> m a) ->
   m a
-withStoreEnv isDerivation names cb = do
+withStoreEnv StoreEnvOptions {seoIsDerivation, seoIsImpure} names cb = do
   nixStore <- liftIO getNixStore
 
   -- See: https://github.com/utdemir/nix-tree/issues/12
   nixVersion <- liftIO getNixVersion
 
-  when (isDerivation && nixVersion < Nix2_4) $
+  when (seoIsDerivation && nixVersion < Nix2_4) $
     liftIO $
       hPutStrLn stderr "Warning: --derivation flag is ignored on Nix versions older than 2.4."
 
@@ -211,7 +219,7 @@ withStoreEnv isDerivation names cb = do
       getPathInfo
         nixStore
         nixVersion
-        (PathInfoOptions {pioIsDerivation = isDerivation, pioIsRecursive = False})
+        (PathInfoOptions {pioIsDerivation = seoIsDerivation, pioIsRecursive = False, pioIsImpure = seoIsImpure})
         names
 
   paths <-
@@ -219,7 +227,7 @@ withStoreEnv isDerivation names cb = do
       getPathInfo
         nixStore
         nixVersion
-        (PathInfoOptions {pioIsDerivation = isDerivation, pioIsRecursive = True})
+        (PathInfoOptions {pioIsDerivation = seoIsDerivation, pioIsRecursive = True, pioIsImpure = seoIsImpure})
         (Installable . toText . storeNameToPath . spName <$> roots)
 
   let env =