From b0840f22e53f6a820b11ba538fb3a9b926fb9b29 Mon Sep 17 00:00:00 2001
From: Louis Pilfold <louis@lpil.uk>
Date: Tue, 12 Dec 2023 15:29:01 +0000
Subject: More lessons

---
 lessons/src/lesson026_list_recursion/code.gleam | 13 +++++++++++++
 lessons/src/lesson026_list_recursion/text.html  | 22 ++++++++++++++++++++++
 2 files changed, 35 insertions(+)
 create mode 100644 lessons/src/lesson026_list_recursion/code.gleam
 create mode 100644 lessons/src/lesson026_list_recursion/text.html

(limited to 'lessons/src/lesson026_list_recursion')

diff --git a/lessons/src/lesson026_list_recursion/code.gleam b/lessons/src/lesson026_list_recursion/code.gleam
new file mode 100644
index 0000000..370675a
--- /dev/null
+++ b/lessons/src/lesson026_list_recursion/code.gleam
@@ -0,0 +1,13 @@
+import gleam/io
+
+pub fn main() {
+  let sum = sum_list([18, 56, 35, 85, 91], 0)
+  io.debug(sum)
+}
+
+fn sum_list(list: List(Int), total: Int) -> Int {
+  case list {
+    [first, ..rest] -> sum_list(rest, total + first)
+    [] -> total
+  }
+}
diff --git a/lessons/src/lesson026_list_recursion/text.html b/lessons/src/lesson026_list_recursion/text.html
new file mode 100644
index 0000000..7f2351d
--- /dev/null
+++ b/lessons/src/lesson026_list_recursion/text.html
@@ -0,0 +1,22 @@
+<p>
+  Most commonly functions in the 
+  <a href="https://hexdocs.pm/gleam_stdlib/gleam/list.html"><code>gleam/list</code></a>
+  module are used to iterate across a list, but at times you may prefer
+  to work with the list directly.
+</p>
+<p>
+  Gleam doesn't have a looping syntax, instead iteration is done through
+  recursion and pattern matching.
+</p> 
+<p>
+  The <code>[first, ..rest]</code> pattern matches on a list with at least one
+  element, assigning the first element to the variable <code>first</code> and
+  the rest of the list to the variable <code>rest</code>.
+  By using this pattern and a pattern for the empty list <code>[]</code> a
+  function can run code on each element of a list until the end is reached.
+</p>
+<p>
+  This code sums a list by recursing over the list and adding each int to a
+  <code>total</code> argument, returning it when the end is reached.
+</p>
+
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