lambda syntax added

docs/advanced_topics.md

@@ -2,24 +2,24 @@
 
 ## Closures/scopes isolation
 
-Each block has own scope, in which it can safely uses closures and override
-outer vars:
-
-> blocks are no-yet-ready lambda declaration so this sample will soon be altered
+Each block has own scope, in which it can safely use closures and override
+outer vars. Lets use some lambdas to create isolated scopes:
 
     var param = "global"
     val prefix = "param in "
+  
     val scope1 = {
         var param = prefix + "scope1"
         param
     }
+    
     val scope2 = {
         var param = prefix + "scope2"
         param
     }
-    // note that block returns its last value
-    println(scope1)
-    println(scope2)
+    
+    println(scope1())
+    println(scope2())
     println(param)
     >>> param in scope1
     >>> param in scope2
@@ -38,7 +38,9 @@ One interesting way of using closure isolation is to keep state of the functions
             counter = counter + 1
             was
         }
-    }
+    }()
+    // notice using of () above: it calls the lambda block that returns
+    // a function (callable!) that we will use:
     println(getAndIncrement())
     println(getAndIncrement())
     println(getAndIncrement())
@@ -49,4 +51,27 @@ One interesting way of using closure isolation is to keep state of the functions
 
 Inner `counter` is not accessible from outside, no way; still it is kept 
 between calls in the closure, as inner function `doit`, returned from the
-block, keeps reference to it and keeps it alive.
+block, keeps reference to it and keeps it alive.
+
+The example above could be rewritten using inner lambda, too:
+
+    val getAndIncrement = {
+        // will be updated by doIt()
+        var counter = 0
+
+        // we return callable fn from the block:
+        {
+            val was = counter
+            counter = counter + 1
+            was
+        }
+    }()
+    // notice using of () above: it calls the lambda block that returns
+    // a function (callable!) that we will use:
+    println(getAndIncrement())
+    println(getAndIncrement())
+    println(getAndIncrement())
+    >>> 0
+    >>> 1
+    >>> 2
+    >>> void