extract service output watcher to fennel module

pkgs/anoia/default.nix

@@ -10,7 +10,9 @@ in stdenv.mkDerivation {
   src = ./.;
   nativeBuildInputs = [ fennel ];
   buildPhase = ''
-    fennel --compile init.fnl > init.lua
+    for f in *.fnl ; do
+      fennel --compile $f > `basename $f .fnl`.lua
+    done
   '';
   installPhase = ''
     mkdir -p "$out/share/lua/${lua.luaversion}/${pname}"

pkgs/anoia/svc.fnl

@@ -0,0 +1,31 @@
+(local inotify (require :inotify))
+(local { : file-exists? } (require :anoia))
+
+(fn read-line [name]
+  (with-open [f (assert (io.open name :r) (.. "can't open file " name))]
+    (f:read "*l")))
+
+(fn watch-fsevents [directory-name]
+  (let [handle (inotify.init)]
+    (handle:addwatch directory-name
+                     inotify.IN_CREATE
+                     inotify.IN_MOVE
+                     inotify.IN_DELETE
+                     inotify.IN_DELETE_SELF
+                     inotify.IN_MOVED_FROM
+                     inotify.IN_MOVED_TO
+                     inotify.IN_CLOSE_WRITE)
+    handle))
+
+(fn open [directory]
+  (let [watcher (watch-fsevents directory)
+        has-file? (fn [filename] (file-exists? (.. directory "/" filename)))]
+    {
+     :wait (fn [] (watcher:read))
+     :ready? (fn [self]
+               (and (has-file? "state") (not (has-file? ".lock"))))
+     :output (fn [_ filename] (read-line (.. directory "/" filename)))
+     :close #(watcher:close)
+     }))
+
+{ : open }