Add explanation of REPL to README.md

README.md

@@ -31,6 +31,66 @@ JSON file as variable in program which runs on node.js
     .exec();
 [how to use ...](./document/how2use.md)
 
+# REPL
+Supports REPL feature.
+````
+$ sudo npm install -g json.filed
+$ json.filed
+> hello = jf.filed('./hello.json')
+filedExecuter {
+  parent: null,
+  io: [Function],
+  read: [Function],
+  in: [Function],
+  write: [Function],
+  out: [Function],
+  copy: [Function],
+  link: [Function],
+  pass: [Function],
+  filter: [Function],
+  calledback: [Function],
+  httpServe: [Function],
+  parallel: [Function],
+  collect: [Function],
+  exec: [Function],
+  plan: [Function],
+  file: [Function],
+  _events: { error: [Function] },
+  _eventsCount: 1 }
+> hello.read( o => { val = o }).exec()
+rootPlan {
+  _nextPlan:
+   executePlan {
+     _nextPlan:
+      notexecPlan {
+        _nextPlan: null,
+        next: [Function],
+        exec: [Function],
+        runtime: [Object] },
+     next: [Function],
+     exec: [Function],
+     runtime:
+      runtimeInformation {
+        collect: [Function],
+        addJsonFile: [Function],
+        removeJsonFile: [Function],
+        resetJsonFile: [Function],
+        countInProgress: [Function] } },
+  next: [Function],
+  exec: [Function],
+  fixedFiles: [ JsonFile { path: [Function] } ],
+  runtime:
+   runtimeInformation {
+     collect: [Function],
+     addJsonFile: [Function],
+     removeJsonFile: [Function],
+     resetJsonFile: [Function],
+     countInProgress: [Function] } }
+> val
+{ msg: 'Hello World' }
+````
+
+
 # Deferred
 Reading and writing file and so on are executed in [deferred manner](./document/HowDeferred.md) to make best use of node.js.