From 2da2c56c72e7085bd9a52f848df90c6fc701de7f Mon Sep 17 00:00:00 2001
From: hachem <im@hachem.wtf>
Date: Sat, 19 Sep 2026 22:04:44 +0200
Subject: docs: add tutorial

---
 tutorial/03_variables.sfinae | 46 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 tutorial/03_variables.sfinae

(limited to 'tutorial/03_variables.sfinae')

diff --git a/tutorial/03_variables.sfinae b/tutorial/03_variables.sfinae
new file mode 100644
index 0000000..6f200f1
--- /dev/null
+++ b/tutorial/03_variables.sfinae
@@ -0,0 +1,46 @@
+// lesson 3: variables
+//
+// a name is a list of characters. a variable holds a type, not a value, and the
+// only type that carries a value is ::decltype(...). the ::conditional_t around
+// it is not required. it is just what everyone does
+
+::declare<
+    ::name<'x'>,
+    ::conditional_t<
+        ::true_type::value,
+        ::decltype(::difference<'F', 'A'>),
+        ::void
+    >
+>::commit;
+
+// reading it back is ::value_of<NAME>, which is a value, so ::decltype it again
+
+::emit<::decltype(::value_of<::name<'x'>>)>::commit;
+
+::declare<
+    ::name<'y'>,
+    ::decltype(
+        ::sum<
+            ::value_of<::name<'x'>>,
+            ::difference<'B', 'A'>
+        >
+    )
+>::commit;
+
+::emit<::decltype(::value_of<::name<'y'>>)>::commit;
+
+// there is no assignment. to change x, undeclare it and declare it again
+
+::undeclare<::name<'x'>>::commit;
+
+::declare<
+    ::name<'x'>,
+    ::decltype(
+        ::product<
+            ::value_of<::name<'y'>>,
+            ::difference<'C', 'A'>
+        >
+    )
+>::commit;
+
+::emit<::decltype(::value_of<::name<'x'>>)>::commit;
-- 
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