From 64eb4e46ecffb6abd4a845c2db61d379642aa7c8 Mon Sep 17 00:00:00 2001
From: brandon s allbery kf8nh <allbery.b@gmail.com>
Date: Sat, 20 Aug 2022 12:00:28 -0400
Subject: [PATCH 1/2] modify `mkAbsolutePath` to support environment vars

If you want more general support, comment on PR #744.
---
 CHANGES.md        |  4 ++++
 XMonad/Prelude.hs | 26 +++++++++++++++++---------
 2 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index c5d33eb2b2..457ce10457 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -184,6 +184,10 @@
     - Added `WindowScreen`, which is a type synonym for the specialized `Screen`
       type, that results from the `WindowSet` definition in `XMonad.Core`.
 
+    - Modified `mkAbsolutePath` to support a leading environment variable, so
+      things like `$HOME/NOTES` work. If you want more general environment
+      variable support, comment on [this PR].
+
   * `XMonad.Util.XUtils`
 
     - Added `withSimpleWindow`, `showSimpleWindow`, `WindowConfig`, and
diff --git a/XMonad/Prelude.hs b/XMonad/Prelude.hs
index 466290d6c4..721038f436 100644
--- a/XMonad/Prelude.hs
+++ b/XMonad/Prelude.hs
@@ -1,5 +1,6 @@
-{-# LANGUAGE BangPatterns #-}
-{-# LANGUAGE LambdaCase   #-}
+{-# LANGUAGE BangPatterns        #-}
+{-# LANGUAGE LambdaCase          #-}
+{-# LANGUAGE ScopedTypeVariables #-}
 --------------------------------------------------------------------
 -- |
 -- Module      :  XMonad.Prelude
@@ -60,6 +61,8 @@ import Data.List.NonEmpty (NonEmpty ((:|)))
 import Data.Tuple (swap)
 import GHC.Stack
 import System.Directory (getHomeDirectory)
+import System.Environment (getEnv)
+import Control.Exception (SomeException, handle)
 import qualified XMonad.StackSet as W
 
 -- | Short for 'fromIntegral'.
@@ -80,7 +83,7 @@ chunksOf i xs = chunk : chunksOf i rest
 (!?) xs n | n < 0 = Nothing
           | otherwise = listToMaybe $ drop n xs
 
--- | Multivariant composition.
+-- | Multivariable composition.
 --
 -- > f .: g ≡ (f .) . g ≡ \c d -> f (g c d)
 (.:) :: (a -> b) -> (c -> d -> a) -> c -> d -> b
@@ -108,14 +111,19 @@ safeGetWindowAttributes w = withDisplay $ \dpy -> io . alloca $ \p ->
 -- * If it starts with @~\/@, replace that with the actual home
 -- * directory.
 --
--- * Otherwise, prepend a @\/@ to the path.
+-- * If it starts with @$@, read the name of an environment
+-- * variable and replace it with the contents of that.
+--
+-- * Otherwise, prepend the home directory and @\/@ to the path.
 mkAbsolutePath :: MonadIO m => FilePath -> m FilePath
 mkAbsolutePath ps = do
-  home <- liftIO getHomeDirectory
-  pure $ case ps of
-    '/'       : _ ->                ps
-    '~' : '/' : _ -> home <> drop 1 ps
-    _             -> home <> ('/' : ps)
+  home <- io getHomeDirectory
+  case ps of
+    '/'       : _ -> pure ps
+    '~' : '/' : _ -> pure (home <> drop 1 ps)
+    '$'       : _ -> let (v,ps') = span (`elem` ("_"<>['A'..'Z']<>['a'..'z']<>['0'..'9'])) (drop 1 ps)
+                      in io ((\(_ :: SomeException) -> pure "") `handle` getEnv v) Exports.<&> (<> ps')
+    _             -> pure (home <> ('/' : ps))
 {-# SPECIALISE mkAbsolutePath :: FilePath -> IO FilePath #-}
 {-# SPECIALISE mkAbsolutePath :: FilePath -> X  FilePath #-}
 

From 2c5ea5f94aee8c5669598316e0376fe5082a1efd Mon Sep 17 00:00:00 2001
From: brandon s allbery kf8nh <allbery.b@gmail.com>
Date: Sat, 20 Aug 2022 12:01:42 -0400
Subject: [PATCH 2/2] change `XMonad.Prompt.AppendFile` to use `mkAbsolutePath`

---
 CHANGES.md                  | 7 +++++++
 XMonad/Prompt/AppendFile.hs | 3 ++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/CHANGES.md b/CHANGES.md
index 457ce10457..bd29dfcf1c 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -94,6 +94,11 @@
 
 ### Bug Fixes and Minor Changes
 
+  * `XMonad.Prompt.AppendFile`
+
+    - Use `XMonad.Prelude.mkAbsolutePath` to force names to be relative to the
+      home directory and support `~/` prefixes.
+
   * `XMonad.Prompt.OrgMode`
 
     - Fixes the date parsing issue such that entries with format of
@@ -225,6 +230,8 @@
 
     - Added a `Default` instance for `UrgencyConfig` and `DzenUrgencyHook`.
 
+[this PR]: https://github.com/xmonad/xmonad-contrib/pull/744
+
 ### Other changes
 
   * Migrated the sample build scripts from the deprecated `xmonad-testing` repo to
diff --git a/XMonad/Prompt/AppendFile.hs b/XMonad/Prompt/AppendFile.hs
index 99fe376df1..f802d737ac 100644
--- a/XMonad/Prompt/AppendFile.hs
+++ b/XMonad/Prompt/AppendFile.hs
@@ -30,6 +30,7 @@ module XMonad.Prompt.AppendFile (
 
 import XMonad.Core
 import XMonad.Prompt
+import XMonad.Prelude (mkAbsolutePath)
 
 import System.IO
 
@@ -91,4 +92,4 @@ appendFilePrompt' c trans fn = mkXPrompt (AppendFile fn)
 
 -- | Append a string to a file.
 doAppend :: (String -> String) -> FilePath -> String -> X ()
-doAppend trans fn = io . withFile fn AppendMode . flip hPutStrLn . trans
+doAppend trans fn s = mkAbsolutePath fn >>= \f -> (io . withFile f AppendMode . flip hPutStrLn . trans) s