Add helper for launching portal

Author: plexus

dev/user.clj

@@ -0,0 +1,17 @@
+(ns user)
+
+(defmacro jit [sym]
+  `(requiring-resolve '~sym))
+
+(def portal-instance (atom nil))
+
+(defn portal
+  "Open a Portal window and register a tap handler for it. The result can be
+  treated like an atom."
+  []
+  ;; Portal is both an IPersistentMap and an IDeref, which confuses pprint.
+  (prefer-method @(jit clojure.pprint/simple-dispatch) clojure.lang.IPersistentMap clojure.lang.IDeref)
+  (let [p ((jit portal.api/open) @portal-instance)]
+    (reset! portal-instance p)
+    (add-tap (jit portal.api/submit))
+    p))