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book/src/language-tour/list.md

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 # List
+
+Aiken lists are plutus linked lists. Accessing by index is O(n). Appending or accessing head is O(1). Grabbing tail is O(1).
+
+There is no builtin syntax for accessing by index as this is implemented by standard libs.
+
+Accessing head, tail, or preceding elements can be done by pattern matching.
+
+```gleam
+// this function checks if a list has a sequence of 1 then 2 contained within it.
+fn listStuff(a: List(Int)){
+    when a is {
+        [1,2, ..tail] -> True
+        []->False
+        _ -> listStuff([2, ..tail])
+    }
+}
+```
+
+Helper functions for safely accessing head, tail, are provided in standard lib but are implemented using comprehensions.
+It is usually best to use your own comprehensions for efficiency (until the optimiser is better).