Fix the REPL-clearing-state bug.

README.md

@@ -61,7 +61,31 @@ make
 And the `cayley` binary will be built and ready.
 
 Give it a quick test with:
-``` ./cayley repl --dbpath=testdata.nt ```
+```
+./cayley repl --dbpath=testdata.nt 
+```
+
+You should see a `cayley>` REPL prompt. Go ahead and give it a try:
+
+```
+// Simple math
+cayley> 2 + 2
+
+// Javascript syntax
+cayley> x = 2 * 8
+cayley> x
+
+// See all the entities in this small follow graph.
+cayley> graph.Vertex().All()
+
+// See only dani.
+cayley> graph.Vertex("dani").All()
+
+// See who dani follows.
+cayley> graph.Vertex("dani").Out("follows").All()
+```
+
+**Sample Data**
 
 For somewhat more interesting data, a sample of 30k movies from Freebase comes in the checkout. 
 

src/cayley_cmd/cayley-repl.go

@@ -69,7 +69,7 @@ func CayleyRepl(ts graph.TripleStore, queryLanguage string, config *cfg.CayleyCo
 	case "gremlin":
 		fallthrough
 	default:
-		ses = gremlin.NewGremlinSession(ts, config.GremlinTimeout)
+		ses = gremlin.NewGremlinSession(ts, config.GremlinTimeout, true)
 	}
 	inputBf := bufio.NewReader(os.Stdin)
 	line := ""

src/cayley_http/cayley-http-query.go

@@ -69,7 +69,7 @@ func (api *Api) ServeV1Query(w http.ResponseWriter, r *http.Request, params http
 	var ses graph.HttpSession
 	switch params.ByName("query_lang") {
 	case "gremlin":
-		ses = gremlin.NewGremlinSession(api.ts, api.config.GremlinTimeout)
+		ses = gremlin.NewGremlinSession(api.ts, api.config.GremlinTimeout, false)
 	case "mql":
 		ses = mql.NewMqlSession(api.ts)
 	default:
@@ -118,7 +118,7 @@ func (api *Api) ServeV1Shape(w http.ResponseWriter, r *http.Request, params http
 	var ses graph.HttpSession
 	switch params.ByName("query_lang") {
 	case "gremlin":
-		ses = gremlin.NewGremlinSession(api.ts, api.config.GremlinTimeout)
+		ses = gremlin.NewGremlinSession(api.ts, api.config.GremlinTimeout, false)
 	case "mql":
 		ses = mql.NewMqlSession(api.ts)
 	default:

src/gremlin/gremlin-session.go

@@ -37,15 +37,19 @@ type GremlinSession struct {
 	script               *otto.Script
 	doHalt               bool
 	timeoutSec           time.Duration
+	emptyEnv             *otto.Otto
 }
 
-func NewGremlinSession(inputTripleStore graph.TripleStore, timeoutSec int) *GremlinSession {
+func NewGremlinSession(inputTripleStore graph.TripleStore, timeoutSec int, persist bool) *GremlinSession {
 	var g GremlinSession
 	g.ts = inputTripleStore
 	g.env = BuildGremlinEnv(&g)
 	g.limit = -1
 	g.count = 0
 	g.lookingForQueryShape = false
+	if persist {
+		g.emptyEnv = g.env
+	}
 	if timeoutSec < 0 {
 		g.timeoutSec = time.Duration(-1)
 	} else {
@@ -127,7 +131,7 @@ func (g *GremlinSession) runUnsafe(input interface{}) (otto.Value, error) {
 				g.env.Interrupt <- func() {
 					panic(halt)
 				}
-				g.env = nil
+				g.env = g.emptyEnv
 			}
 		}()
 	}
@@ -159,7 +163,7 @@ func (g *GremlinSession) ExecInput(input string, out chan interface{}, limit int
 	}
 	g.currentChannel = nil
 	g.script = nil
-	g.env = nil
+	g.env = g.emptyEnv
 	return
 }