From 4530fe3ad3f0488a6c5c027025a3bdc20b5e5fbe Mon Sep 17 00:00:00 2001
From: Yorkin <cyb_yorkin@outlook.com>
Date: Wed, 25 Dec 2024 17:20:57 +0800
Subject: [PATCH] tour: add lesson for newtype (#384)

---
 .../tour/chapter2_data_types/lesson4_newtype/index.mbt      | 5 +++--
 .../tour/chapter2_data_types/lesson4_newtype/index.md       | 6 ++++++
 .../{lesson4_option => lesson5_option}/index.mbt            | 0
 .../{lesson4_option => lesson5_option}/index.md             | 0
 .../{lesson5_result => lesson6_result}/index.mbt            | 0
 .../{lesson5_result => lesson6_result}/index.md             | 0
 6 files changed, 9 insertions(+), 2 deletions(-)
 rename moonbit-tour/tour/chapter2_data_types/{lesson4_option => lesson5_option}/index.mbt (100%)
 rename moonbit-tour/tour/chapter2_data_types/{lesson4_option => lesson5_option}/index.md (100%)
 rename moonbit-tour/tour/chapter2_data_types/{lesson5_result => lesson6_result}/index.mbt (100%)
 rename moonbit-tour/tour/chapter2_data_types/{lesson5_result => lesson6_result}/index.md (100%)

diff --git a/moonbit-tour/tour/chapter2_data_types/lesson4_newtype/index.mbt b/moonbit-tour/tour/chapter2_data_types/lesson4_newtype/index.mbt
index 3fc4a2de..717137ad 100644
--- a/moonbit-tour/tour/chapter2_data_types/lesson4_newtype/index.mbt
+++ b/moonbit-tour/tour/chapter2_data_types/lesson4_newtype/index.mbt
@@ -4,8 +4,9 @@ type UserName String
 fn main {
   let user_id : UserId = UserId(1)
   let user_name : UserName = UserName("Alice")
-  let UserId(id) = user_id
-  let UserName(name) = user_name
   println(user_id._)
   println(user_name._)
+  // use some pattern matching to extract the values
+  let UserId(id) = user_id 
+  let UserName(name) = user_name
 }
diff --git a/moonbit-tour/tour/chapter2_data_types/lesson4_newtype/index.md b/moonbit-tour/tour/chapter2_data_types/lesson4_newtype/index.md
index e69de29b..7143fd9c 100644
--- a/moonbit-tour/tour/chapter2_data_types/lesson4_newtype/index.md
+++ b/moonbit-tour/tour/chapter2_data_types/lesson4_newtype/index.md
@@ -0,0 +1,6 @@
+# Newtype
+
+Newtypes are similar to enums with only one constructor (with the same name as the newtype itself). You can use the constructor to create values of the newtype and use `._` to extract the internal representation. 
+
+*Pattern matching* can also be used.
+
diff --git a/moonbit-tour/tour/chapter2_data_types/lesson4_option/index.mbt b/moonbit-tour/tour/chapter2_data_types/lesson5_option/index.mbt
similarity index 100%
rename from moonbit-tour/tour/chapter2_data_types/lesson4_option/index.mbt
rename to moonbit-tour/tour/chapter2_data_types/lesson5_option/index.mbt
diff --git a/moonbit-tour/tour/chapter2_data_types/lesson4_option/index.md b/moonbit-tour/tour/chapter2_data_types/lesson5_option/index.md
similarity index 100%
rename from moonbit-tour/tour/chapter2_data_types/lesson4_option/index.md
rename to moonbit-tour/tour/chapter2_data_types/lesson5_option/index.md
diff --git a/moonbit-tour/tour/chapter2_data_types/lesson5_result/index.mbt b/moonbit-tour/tour/chapter2_data_types/lesson6_result/index.mbt
similarity index 100%
rename from moonbit-tour/tour/chapter2_data_types/lesson5_result/index.mbt
rename to moonbit-tour/tour/chapter2_data_types/lesson6_result/index.mbt
diff --git a/moonbit-tour/tour/chapter2_data_types/lesson5_result/index.md b/moonbit-tour/tour/chapter2_data_types/lesson6_result/index.md
similarity index 100%
rename from moonbit-tour/tour/chapter2_data_types/lesson5_result/index.md
rename to moonbit-tour/tour/chapter2_data_types/lesson6_result/index.md