Merge #987: specializing Path functions; enabling some tests; clean-up & refactors

Specialization of former `FilePath` functions to `Path` happens mainly to:

1. Prune String from code as much as possible and to maximally avoid conversions in the end.
2. To have typesafe code (I/somebody still should remove `Monoid` for `Path`).
3. Main reason: further to have an easy decision making how to control & process `Path`s and to have breather migration to `path` package (probably), which would make it even more realistic & typesafe code.

Author: Anton-Latukha

hnix.cabal

@@ -464,7 +464,7 @@ library
     , time >= 1.8.0 && < 1.9 || >= 1.9.3 && < 1.10
     , transformers >= 0.5.5 && < 0.6
     , transformers-base >= 0.4.5 && < 0.5
-    , unix >= 2.7.2 && < 2.8
+    , unix-compat >= 0.4.3 && < 0.6
     , unordered-containers >= 0.2.9 && < 0.3
     , vector >= 0.12.0 && < 0.13
     , xml >= 1.3.14 && < 1.4
@@ -613,7 +613,7 @@ test-suite hnix-tests
     , serialise
     , template-haskell
     , time
-    , unix
+    , unix-compat
   default-extensions:
       OverloadedStrings
     , DeriveGeneric

main/Main.hs

@@ -32,7 +32,6 @@ import           Options.Applicative     hiding ( ParserResult(..) )
 import           Prettyprinter           hiding ( list )
 import           Prettyprinter.Render.Text      ( renderIO )
 import qualified Repl
-import           System.FilePath
 import           Nix.Eval
 
 main :: IO ()
@@ -72,15 +71,16 @@ main' opts@Options{..} = runWithBasicEffectsIO opts execContentsFilesOrRepl
           expr <- liftIO Text.getContents
           processExpr expr
 
-    processSeveralFiles files = traverse_ processFile files
+    processSeveralFiles :: [Path] -> StandardT (StdIdT IO) ()
+    processSeveralFiles = traverse_ processFile
      where
       processFile path = handleResult (pure path) =<< parseNixFileLoc path
 
     -- |  The `--read` option: load expression from a serialized file.
     loadBinaryCacheFile =
       (\ (binaryCacheFile :: Path) ->
         do
-          let file = coerce $ (replaceExtension . coerce) binaryCacheFile "nixc"
+          let file = replaceExtension binaryCacheFile "nixc"
           processCLIOptions (Just file) =<< liftIO (readCache binaryCacheFile)
       ) <$> readFrom
 
@@ -160,7 +160,7 @@ main' opts@Options{..} = runWithBasicEffectsIO opts execContentsFilesOrRepl
     | xml                        = fail "Rendering expression trees to XML is not yet implemented"
     | json                       = fail "Rendering expression trees to JSON is not implemented"
     | verbose >= DebugInfo       =  liftIO . putStr . ppShow . stripAnnotation $ expr
-    | cache , Just path <- mpath =  liftIO . writeCache (coerce $ replaceExtension (coerce path) "nixc") $ expr
+    | cache , Just path <- mpath =  liftIO . writeCache (replaceExtension path "nixc") $ expr
     | parseOnly                  =  void . liftIO . Exception.evaluate . force $ expr
     | otherwise                  =
       liftIO .