[LTB-13] A couple of utilities for executable binaries

code/bin/LICENCE

@@ -0,0 +1 @@
+../base/LICENCE

code/bin/README.md

@@ -0,0 +1,4 @@
+loot-bin
+=========
+
+_Some fine utilities for your executables._

code/bin/lib/Loot/Bin/IO.hs

@@ -0,0 +1,21 @@
+-- | Utilities for performing IO
+module Loot.Bin.IO
+       ( openFileOrStdin
+       , withFileOrStdin
+       ) where
+
+import Control.Exception.Safe (bracket)
+import System.IO (Handle, IOMode (ReadMode), hClose, stdin)
+
+
+-- | Like 'openFile' but if the filename is @-@ returns 'stdin'.
+--
+-- Always opens the file in 'ReadMode'.
+openFileOrStdin :: MonadIO m => FilePath -> m Handle
+openFileOrStdin "-"  = pure stdin
+openFileOrStdin name = openFile name ReadMode
+
+-- | Like 'withFile', but also like 'openFileOrStdin'.
+withFileOrStdin :: (MonadIO m, MonadMask m) => FilePath -> (Handle -> m r) -> m r
+withFileOrStdin "-"  cont = cont stdin
+withFileOrStdin name cont = bracket (openFile name ReadMode) (liftIO . hClose) cont

code/bin/lib/Loot/Bin/Paths.hs

@@ -0,0 +1,41 @@
+-- | Utilities for locating files according to the XDG Base Directory Specification.
+--
+-- A good way to reuse this module is to create a module called @Paths@ in your
+-- project and define in it:
+--
+-- @
+-- appName :: String
+-- appName = "\<your app name\>"
+--
+-- getDataDir :: MonadIO m => m FilePath
+-- getDataDir = 'getDataDirFor' appName
+--
+-- getConfigDir :: MonadIO m => m FilePath
+-- getConfigDir = 'getConfigDirFor' appName
+--
+-- getCacheDir :: MonadIO m => m FilePath
+-- getCacheDir = 'getCacheDirFor' appName
+-- @
+--
+-- And then make sure your application places files in the right directories.
+module Loot.Bin.Paths
+       ( getDataDirFor
+       , getConfigDirFor
+       , getCacheDirFor
+       ) where
+
+import System.Directory (XdgDirectory (XdgCache, XdgConfig, XdgData), getXdgDirectory)
+import System.IO (FilePath)
+
+
+-- | Returns the path to the data directory for your application.
+getDataDirFor :: MonadIO m => String -> m FilePath
+getDataDirFor = liftIO . getXdgDirectory XdgData
+
+-- | Returns the path to the config directory for your application.
+getConfigDirFor :: MonadIO m => String -> m FilePath
+getConfigDirFor = liftIO . getXdgDirectory XdgConfig
+
+-- | Returns the path to the cache directory for your application.
+getCacheDirFor :: MonadIO m => String -> m FilePath
+getCacheDirFor = liftIO . getXdgDirectory XdgCache

code/bin/package.yaml

@@ -0,0 +1,10 @@
+<<: !include "../base/hpack/lib.yaml"
+
+name: loot-bin
+
+library:
+  <<: *lib-common
+
+  dependencies:
+    - directory
+    - safe-exceptions

stack.yaml

@@ -2,6 +2,7 @@ resolver: snapshot.yaml
 
 packages:
   - code/base
+  - code/bin
   - code/config
   - code/crypto
   - code/log