1 files changed, 61 insertions, 0 deletions
diff --git a/tutorial/02_numbers.sfinae b/tutorial/02_numbers.sfinae
new file mode 100644
index 0000000..76f7dca
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+++ b/tutorial/02_numbers.sfinae
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+// lesson 2: numbers
+//
+// a digit is a syntax error. the only number literal is ::difference<'a', 'b'>,
+// the distance between two characters. 'F' - 'A' is 5. ::emit takes a type, and a 
+// value is not a type, so wrap it in ::decltype(...) to make it one
+
+::emit<::decltype(::difference<'F', 'A'>)>::commit;
+
+// arithmetic is ::sum, ::product and ::quotient. 
+// no operators
+// no precedence
+// no problem
+
+::emit<
+    ::decltype(
+        ::sum<
+            ::difference<'F', 'A'>,
+            ::difference<'C', 'A'>
+        >
+    )
+>::commit;
+
+::emit<
+    ::decltype(
+        ::product<
+            ::difference<'D', 'A'>,
+            ::difference<'E', 'A'>
+        >
+    )
+>::commit;
+
+::emit<
+    ::decltype(
+        ::quotient<
+            ::difference<'H', 'A'>,
+            ::difference<'C', 'A'>
+        >
+    )
+>::commit;
+
+// ::integral_constant<::size_t, V>::value is V. it exists so you can write more
+// ::extent<T>::value is the length of an array type, and 0 for anything else
+// this is the long way to write 20
+
+::emit<
+    ::decltype(
+        ::extent<
+            ::array<
+                ::byte,
+                ::integral_constant<
+                    ::size_t,
+                    ::difference<'Z', 'F'>
+                >::value
+            >
+        >::value
+    )
+>::commit;
+
+// emitting a type that is not a value prints the name of the type
+
+::emit<::remove_cv_t<::int32_t>>::commit;