From 2a6ae1fa5408247c95bf4a7d59e5038342a2a125 Mon Sep 17 00:00:00 2001
From: Louis Pilfold <louis@lpil.uk>
Date: Wed, 20 Dec 2023 20:46:44 +0000
Subject: Nil and bit arrays

---
 lessons/src/lesson035_nil/code.gleam        | 11 +++++++++++
 lessons/src/lesson035_nil/text.html         | 15 +++++++++++++++
 lessons/src/lesson036_bit_arrays/code.gleam | 13 +++++++++++++
 lessons/src/lesson036_bit_arrays/text.html  | 26 ++++++++++++++++++++++++++
 4 files changed, 65 insertions(+)
 create mode 100644 lessons/src/lesson035_nil/code.gleam
 create mode 100644 lessons/src/lesson035_nil/text.html
 create mode 100644 lessons/src/lesson036_bit_arrays/code.gleam
 create mode 100644 lessons/src/lesson036_bit_arrays/text.html

(limited to 'lessons/src')

diff --git a/lessons/src/lesson035_nil/code.gleam b/lessons/src/lesson035_nil/code.gleam
new file mode 100644
index 0000000..c28080b
--- /dev/null
+++ b/lessons/src/lesson035_nil/code.gleam
@@ -0,0 +1,11 @@
+import gleam/io
+
+pub fn main() {
+  let x = Nil
+  io.debug(x)
+
+  // let y: List(String) = Nil
+
+  let result = io.println("Hello!")
+  io.debug(result == Nil)
+}
diff --git a/lessons/src/lesson035_nil/text.html b/lessons/src/lesson035_nil/text.html
new file mode 100644
index 0000000..3416643
--- /dev/null
+++ b/lessons/src/lesson035_nil/text.html
@@ -0,0 +1,15 @@
+<p>
+  <code>Nil</code> is Gleam's unit type. It is a value that is returned by
+  functions that have nothing else to return, as all functions much return
+  something.
+</p>
+<p>
+  <code>Nil</code> is not a valid value of any other types, that is values in
+  Gleam are not nullable. If the type of a value is <code>Nil</code> then it is
+  the value <code>nil</code>. If it is some other type then the value is not
+  <code>Nil</code>.
+</p>
+<p>
+  Uncomment the line that assigns <code>Nil</code> to a variable with an
+  incompatible type annotation to see the comile time error it produces.
+</p>
diff --git a/lessons/src/lesson036_bit_arrays/code.gleam b/lessons/src/lesson036_bit_arrays/code.gleam
new file mode 100644
index 0000000..dc772ca
--- /dev/null
+++ b/lessons/src/lesson036_bit_arrays/code.gleam
@@ -0,0 +1,13 @@
+import gleam/io
+
+pub fn main() {
+  // 8 bit int. In binary: 00000011
+  io.debug(<<3>>)
+  io.debug(<<3>> == <<3:size(8)>>)
+
+  // 16 bit int. In binary: 0001100000000011
+  io.debug(<<6147:size(16)>>)
+
+  // A bit array of UTF8 data
+  io.debug(<<"Hello, Joe!":utf8>>)
+}
diff --git a/lessons/src/lesson036_bit_arrays/text.html b/lessons/src/lesson036_bit_arrays/text.html
new file mode 100644
index 0000000..3214db1
--- /dev/null
+++ b/lessons/src/lesson036_bit_arrays/text.html
@@ -0,0 +1,26 @@
+<p>
+  Bit arrays represent a sequence of 1s and 0s, and are a convenient syntax for
+  constructing and manipulating binary data.
+</p>
+<p>
+  Each segment of a bit array can be given options to specify the representation
+  used for that segment.
+</p>
+<ul>
+  <li><code>size</code>: the size of the segment in bits.</li>
+  <li><code>unit</code>: how many times to repeat the segment.</li>
+  <li><code>bits</code>: a nested bit array of any size.</li>
+  <li><code>bytes</code>: a nested byte-aligned bit array.</li>
+  <li><code>float</code>: a 64 bits floating point number.</li>
+  <li><code>int</code>: an int with a default size of 8 bits.</li>
+  <li><code>big</code>: big endian.</li>
+  <li><code>little</code>: little endian.</li>
+  <li><code>native</code>: the endianness of the processor.</li>
+  <li><code>utf8</code>: utf8 encoded text.</li>
+  <li><code>utf16</code>: utf16 encoded text.</li>
+  <li><code>utf32</code>: utf32 encoded text.</li>
+</ul>
+<p>
+  Bit arrays have limited support when compiling to JavaScript, not all options
+  can be used. Full bit array support will be implemented in future.
+</p>
-- 
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