Guards

2 files changed, 24 insertions, 0 deletions

diff --git a/src/content/chapter2_flow_control/lesson09_guards/code.gleam b/src/content/chapter2_flow_control/lesson09_guards/code.gleam
new file mode 100644
index 0000000..3744228
--- /dev/null
+++ b/src/content/chapter2_flow_control/lesson09_guards/code.gleam
@@ -0,0 +1,15 @@
+import gleam/io
+
+pub fn main() {
+  let numbers = [1, 2, 3, 4, 5]
+  io.debug(get_first_larger(numbers, 3))
+  io.debug(get_first_larger(numbers, 5))
+}
+
+fn get_first_larger(lists: List(Int), limit: Int) -> Int {
+  case lists {
+    [first, ..] if first > limit -> first
+    [_, ..rest] -> get_first_larger(rest, limit)
+    [] -> 0
+  }
+}
diff --git a/src/content/chapter2_flow_control/lesson09_guards/text.html b/src/content/chapter2_flow_control/lesson09_guards/text.html
new file mode 100644
index 0000000..3ea9cc5
--- /dev/null
+++ b/src/content/chapter2_flow_control/lesson09_guards/text.html
@@ -0,0 +1,9 @@
+<p>
+  The <code>if</code> keyword can be used with case expressions to add a
+  <em>guard</em> to a pattern. A guard is an expression that must evaluate to
+  <code>True</code> for the pattern to match.
+</p>
+<p>
+  Only a limited set of operators can be used in guards, and functions cannot be
+  called at all.
+</p>