Update examples to use StreamNode and Series with lookback

The `PipelineNode` has been refactored into `StreamNode`. This commit
updates the example files to reflect this change and also updates the
`series` constructor to accept a lookback parameter.

The `PipelineNode` was an artifact of a previous implementation and is
no longer needed. The `StreamNode` is the appropriate type for
representing the output of a pipe operation.

The `series` function now requires a `lookback` argument to specify the
maximum number of items to store. This makes the behavior of series more
explicit and prevents accidental unbounded memory growth.

examples/pipeline.myc

@@ -1,6 +1,6 @@
-;; Benchmark: 2.1us
-;; Benchmark-Repeat: 921
-;; Output: PipelineNode[last: Some(110.45243843391206)]
+;; Benchmark: 2.1us
+;; Benchmark-Repeat: 921
+;; Output: <StreamNode>
 
 (do
   (def src1 (create-random-ohlc 42 3))

examples/pipeline_script_ticker.myc

@@ -1,6 +1,6 @@
 ;; Benchmark: 3.2us
 ;; Benchmark-Repeat: 613
-;; Output: PipelineNode[last: Some(110.45243843391206)]
+;; Output: <StreamNode>
 
 (do
   ;; Set the random seed to match the existing test output exactly

examples/record_specialization_test.myc

@@ -1,11 +1,11 @@
-;; Benchmark: 1.5us
-;; Benchmark-Repeat: 1348
+;; Benchmark: 1.5us
+;; Benchmark-Repeat: 1348
 ;; Test Record SoA specialization in Pipelines
 ;; Dank der neuen Spezialisierung wird hierfür im Hintergrund 
 ;; eine SharedRecordSeries mit SoA-Layout (Float-Puffer für mid und range) erstellt.
 
-;; Output: PipelineNode[last: Some({:mid 101.35623617501585, :range 0.9314056584827455})]
-
+;; Output: <StreamNode>
+
 (do
   (def ohlc_stream (create-random-ohlc 42 10))
 

examples/sma.myc

@@ -1,12 +1,22 @@
 #use rtl
 
 (do
-  (def src (create-random-ohlc 42 200))
+  (def src (create-random-ohlc 42 20000))
+
+  (macro printx [s] `(fn [x] (print ~s x)))
+
+;  (pipe src print)
+;  (pipe [(pipe [(.close src)] (SMA 20))] (printx "sma20="))
+;  (pipe [(pipe [(.close src)] (SMA 5))] (printx "sma5="))
+;  (pipe [(pipe [(.close src)] (SMA 100))] (printx "sma100="))
 
-  (macro printx [s] `(fn [x] (print ~s x)))
+(macro cache [lookback type src] `(do (def data (series ~lookback ~type)) (pipe [~src] (fn [s] (do (push data s)))) data))
 
-  (pipe src print) 
-  (pipe [(pipe [(.close src)] (SMA 20))] (printx "sma20="))
-  (pipe [(pipe [(.close src)] (SMA 5))] (printx "sma5="))
-  (pipe [(pipe [(.close src)] (SMA 100))] (printx "sma100="))
-)
+
+
+;  (def bars (series 20 :float))
+;  (pipe [src] (fn [s] (do (push bars (.close s)))))
+
+(cache 20 :float src)
+  
+)

examples/soa_series.myc

@@ -2,7 +2,7 @@
 ;; Benchmark: 1.4us
 ;; Benchmark-Repeat: 1406
 (do
-  (def my_ticks (series {:price :float :volume :int :msg :text}))
+  (def my_ticks (series 100 {:price :float :volume :int :msg :text}))
 
   (push my_ticks {:price 10.5 :volume 100 :msg "A"})
   (push my_ticks {:price 11.2 :volume 200 :msg "B"})