docs(examples): adopt elegant if (var x = m[k]) idiom in map demos

Signed-off-by: Cong Wang <cwang@multikernel.io>

Author: congwang-mk

examples/map_operations_demo.ks

@@ -70,16 +70,13 @@ struct ArrayElement {
 
     // Per-CPU access for maximum performance
     var cpu_id = 0
-    var data = percpu_data[cpu_id]
-    if (data != none) {
+    if (var data = percpu_data[cpu_id]) {
         data.local_counter = data.local_counter + 1
-        percpu_data[cpu_id] = data
     } else {
-        var new_data = PerCpuData {
+        percpu_data[cpu_id] = PerCpuData {
             local_counter: 1,
             temp_storage: [0],
         }
-        percpu_data[cpu_id] = new_data
     }
 
     return XDP_PASS
@@ -157,19 +154,16 @@ fn event_logger(ctx: *trace_event_raw_sys_enter) -> i32 {
 fn data_processor(file: *file, buf: *u8, count: size_t, pos: *i64) -> i32 {
     // Sequential access pattern - will be detected and optimized
     for (i in 0..32) {
-        var element = sequential_data[i]
-        if (element != none) {
+        if (var element = sequential_data[i]) {
             if (!element.processed) {
                 element.value = element.value * 2
                 element.processed = true
-                sequential_data[i] = element
             }
         } else {
-            var new_element = ArrayElement {
+            sequential_data[i] = ArrayElement {
                 value: i,
                 processed: false,
             }
-            sequential_data[i] = new_element
         }
     }
 

examples/maps_demo.ks

@@ -70,28 +70,21 @@ fn get_timestamp() -> u64 {
   var cpu_id = get_cpu_id()
   cpu_counters[cpu_id] = cpu_counters[cpu_id] + 1
 
-  // Update IP statistics - elegant truthy/falsy pattern
-  var stats = ip_stats[src_ip]
-  if (stats != none) {
-    // stats is truthy - entry exists, update it
+  // Update IP statistics - in-place mutation when entry exists
+  if (var stats = ip_stats[src_ip]) {
     stats.count = stats.count + 1
     stats.total_bytes = stats.total_bytes + packet_len
     stats.last_seen = get_timestamp()
-    ip_stats[src_ip] = stats
   } else {
-    // stats is falsy - no entry, create new one
-    var new_stats = PacketStats {
+    ip_stats[src_ip] = PacketStats {
       count: 1,
       total_bytes: packet_len,
       last_seen: get_timestamp()
     }
-    ip_stats[src_ip] = new_stats
   }
-  
-  // Check recent connections
-  var recent = recent_connections[src_ip]
-  if (recent != none) {
-    // Log repeated connection
+
+  // Log repeated connections
+  if (recent_connections[src_ip] != none) {
     event_log[0] = 1
   }