Move lockfile logic into it's own file.

pkg/king/app/Main.hs

@@ -105,6 +105,7 @@ import System.Environment   (getProgName)
 import System.Posix.Signals (Handler(Catch), installHandler, sigTERM)
 import Text.Show.Pretty     (pPrint)
 import Urbit.Time           (Wen)
+import Vere.LockFile        (lockFile)
 
 import qualified CLI
 import qualified Data.Set                    as Set
@@ -196,21 +197,6 @@ tryPlayShip shipPath = do
         rio $ logTrace "SHIP RESUMED"
         Pier.pier shipPath Nothing sls
 
-lockFile :: HasLogFunc e => FilePath -> RAcquire e ()
-lockFile pax = void $ mkRAcquire start stop
-  where
-    fil = pax <> "/.vere.lock"
-
-    stop handle = do
-        logInfo $ display @Text $ ("Releasing lock file: " <> pack fil)
-        io $ Lock.unlock fil handle
-
-    params = def { Lock.retryToAcquireLock = Lock.No }
-
-    start = do
-        logInfo $ display @Text $ ("Taking lock file: " <> pack fil)
-        io (Lock.lock params fil)
-
 tryResume :: HasLogFunc e => FilePath -> RIO e ()
 tryResume shipPath = do
     rwith resumedPier $ \(serf, log, ss) -> do

pkg/king/lib/Vere/LockFile.hs

@@ -0,0 +1,24 @@
+module Vere.LockFile (lockFile) where
+
+import UrbitPrelude
+
+import Data.Default                (def)
+import System.IO.LockFile.Internal (LockingParameters(..), RetryStrategy(..),
+                                    lock, unlock)
+
+--------------------------------------------------------------------------------
+
+lockFile :: HasLogFunc e => FilePath -> RAcquire e ()
+lockFile pax = void $ mkRAcquire start stop
+  where
+    fil = pax <> "/.vere.lock"
+
+    stop handle = do
+        logInfo $ display @Text $ ("Releasing lock file: " <> pack fil)
+        io $ unlock fil handle
+
+    params = def { retryToAcquireLock = No }
+
+    start = do
+        logInfo $ display @Text $ ("Taking lock file: " <> pack fil)
+        io (lock params fil)