From 7be78efb6c56c04b8a96b3f4f7f6cf810da04dbf Mon Sep 17 00:00:00 2001
From: Joel Kronqvist <joel.kronqvist@iki.fi>
Date: Tue, 5 Aug 2025 12:18:11 +0300
Subject: Fixed type of Not, added documentation to the tour for booleans

---
 TUTORIAL.md       | 40 ++++++++++++++++++++++++++++++++++++++++
 src/type/check.rs |  4 ++--
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/TUTORIAL.md b/TUTORIAL.md
index 7389d55..9494859 100644
--- a/TUTORIAL.md
+++ b/TUTORIAL.md
@@ -34,6 +34,46 @@ Decimals are truncated in division:
 ```
 
 
+**Booleans**
+
+Myslip supports booleans and `and`, `or`, `xor` and `not`
+for their comparisons.
+```console
+> true
+true : Bool
+> false
+false : Bool
+> (and true true)
+true : Bool
+> (or true false)
+true : Bool
+> (xor true true)
+false : Bool
+> (not true)
+false : Bool
+```
+
+
+**Integer comparisons**
+
+To generate booleans from integers, some basic and quite
+self-explanatory operators are supplied.
+```console
+> (>  2 1)
+true : Bool
+> (<  1 2)
+true : Bool
+> (>= 1 1)
+true : Bool
+> (<= 1 1)
+true : Bool
+> (=  1 1)
+true : Bool
+> (!= 1 1)
+false : Bool
+```
+
+
 **Lists**
 
 Lists in myslip correspond to what is known as tuples in many
diff --git a/src/type/check.rs b/src/type/check.rs
index d678411..81a43a4 100644
--- a/src/type/check.rs
+++ b/src/type/check.rs
@@ -64,7 +64,7 @@ impl SExp {
     /// assert_eq!(Atom(And).type_check(), Ok(arr(List(vec![Boolean, Boolean]), Boolean)));
     /// assert_eq!(Atom(Or) .type_check(), Ok(arr(List(vec![Boolean, Boolean]), Boolean)));
     /// assert_eq!(Atom(Xor).type_check(), Ok(arr(List(vec![Boolean, Boolean]), Boolean)));
-    /// assert_eq!(Atom(Not).type_check(), Ok(arr(Boolean, Boolean)));
+    /// assert_eq!(Atom(Not).type_check(), Ok(arr(List(vec![Boolean]), Boolean)));
     /// ```
     ///
     /// Though perhaps the most important task of the type system
@@ -147,7 +147,7 @@ impl SExp {
             Atom(Eq | Neq | Lt | Gt | Le | Ge) =>
                 Ok(arr(List(vec![Integer, Integer]), Boolean)),
             Atom(Or | And | Xor) => Ok(arr(List(vec![Boolean, Boolean]), Boolean)),
-            Atom(Not)   => Ok(arr(Boolean, Boolean)),
+            Atom(Not)   => Ok(arr(List(vec!(Boolean)), Boolean)),
             Atom(Nil)   => Ok(List(vec![])),
             Atom(Quote) => Ok(arr(
                                VarType("T".to_string()),
-- 
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