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Task/Singly-linked-list-Traversal/EchoLisp/singly-linked-list-traversal.echolisp

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+(define friends '( albert ludwig elvis 🌀))
+
+(for-each write friends)→  albert ludwig elvis 🌀
+
+; for loop
+(for ((friend friends)) (write friend)) → albert ludwig elvis 🌀
+
+; map a function
+(map string-upcase friends)  → ("ALBERT" "LUDWIG" "ELVIS" "🌀")
+(map string-randcase friends) → ("ALBerT" "LudWIG" "elVis" "🌀")
+
+; recursive way
+(define (rscan L)
+    (unless (null? L)
+        (write (first L))
+         (rscan (rest L))))
+
+(rscan friends)  →  albert ludwig elvis 🌀
+
+; folding a list
+; check that ∑ 1..n = n (n+1)/2
+
+(define L (iota 1001))
+(foldl + 0 L) → 500500 ; 1000 * 1001 / 2