Add support for watching watchers

orx-file-watcher/src/main/kotlin/FileWatcher.kt

@@ -19,6 +19,8 @@ class FileWatcher(private val program: Program, val file: File, private val onCh
                 SensitivityWatchEventModifier.HIGH
         )
     }
+    val watchers = mutableListOf<() -> Unit>()
+
     init {
         watchThread
         watching.getOrPut(path) {
@@ -34,6 +36,7 @@ class FileWatcher(private val program: Program, val file: File, private val onCh
     internal fun triggerChange() {
         program.launch {
             onChange(file)
+            watchers.forEach { it() }
         }
     }
 }
@@ -77,6 +80,21 @@ fun <T> (()->T).triggerChange() {
 }
 
 
+/**
+ * add watcher to file watcher
+ */
+fun <T, R> (() -> T).watch(transducer: (T) -> R):()->R {
+
+    var result = transducer(this())
+
+    watchers[this as () -> Any?]!!.watchers.add {
+        result = transducer(this())
+    }
+
+    return { result }
+}
+
+
 @JvmName("programWatchFile")
 fun <T> Program.watchFile(file: File, transducer: (File) -> T): () -> T = watchFile(this, file, transducer)
 
@@ -110,6 +128,7 @@ fun main() {
         it.readText()
     }
 
+
     a.stop()
     a.triggerChange()