From b04106b038fffc2ea90a2c425bee0c2485ca2003 Mon Sep 17 00:00:00 2001
From: Louis Pilfold <louis@lpil.uk>
Date: Sat, 23 May 2020 18:20:15 +0100
Subject: Document Iterator type

---
 src/gleam/iterator.gleam       | 21 +++++++++++----------
 test/gleam/iterator_test.gleam |  1 -
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/src/gleam/iterator.gleam b/src/gleam/iterator.gleam
index 8a4410d..efde4f5 100644
--- a/src/gleam/iterator.gleam
+++ b/src/gleam/iterator.gleam
@@ -2,24 +2,25 @@ import gleam/list
 
 // Internal private representation of an Iterator
 type Action(element) {
-  // Improper dancing in the middle of the street
-  // Improper dancing in the middle of the street
-  // Improper dancing in the middle of the street
-  // Somebody better notify the chief of police
   Stop
   Continue(element, fn() -> Action(element))
 }
 
-// Yes!
-// Wrapper to hide the internal representation
+/// An iterator is a lazily evaluated sequence of element.
+///
+/// Iterators are useful when working with collections that are too large to
+/// fit in memory (or those that are infinite in size) as they only require the
+/// elements currently being processed to be in memory.
+///
+/// As a lazy data structure no work is done when an iterator is filters,
+/// mapped, etc, instead a new iterator is returned with these transformations
+/// applied to the stream. Once the stream has all the required transformations
+/// applied it can be evaluated using functions such as `fold` and `take`.
+///
 pub opaque type Iterator(element) {
   Iterator(thunk: fn() -> Action(element))
 }
 
-pub fn identity(x) {
-  x
-}
-
 // Public API for iteration
 pub type Step(element, acc) {
   Next(element, acc)
diff --git a/test/gleam/iterator_test.gleam b/test/gleam/iterator_test.gleam
index ec1eac3..015d3b2 100644
--- a/test/gleam/iterator_test.gleam
+++ b/test/gleam/iterator_test.gleam
@@ -2,7 +2,6 @@ import gleam/should
 import gleam/iterator
 import gleam/list
 
-// TODO: Property tests
 // a |> from_list |> to_list == a
 pub fn to_from_list_test() {
   let test = fn(subject) {
-- 
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