From ea8bf634b9c01ec14a2546559e75d4183a8c094f Mon Sep 17 00:00:00 2001
From: Cliff Click <cliffc@acm.org>
Date: Wed, 23 Apr 2025 15:11:09 -0700
Subject: Update README.md

---
 chapter22/README.md | 108 ++++++++++++++++++++++++++++------------------------
 1 file changed, 58 insertions(+), 50 deletions(-)

diff --git a/chapter22/README.md b/chapter22/README.md
index aecc09dc..2c391792 100644
--- a/chapter22/README.md
+++ b/chapter22/README.md
@@ -26,6 +26,62 @@ Includes `sys.io{}` struct with I/O calls.
 Includes `sys.libc{}` with default libc calls.
 
 
+## Structs can be inlined
+
+Structs are normally by-reference, but can be converted to by-value by using
+the `*` operator, pronounced "contents of" (this name might be changed to
+e.g. `inline`).
+
+This is a name-space change only, you cannot take the address of the internal
+struct without entirely consuming its lifetime.  No "escaping".
+
+```java
+// 2 64-bit words, no other overheads
+struct Complex { f64 x,y; var len = { ->Math.sqrt(x*x+y*y); }; };
+
+// Current Simple rules: always by-reference
+struct ByRef {
+    Complex c;          // 4-byte pointer to a Complex
+};
+print(new ByRef.c.y);   // Lookup requires 1 extra memory load from ref to c
+
+// New behavior: by value (inlining a struct)
+// The '*' syntax indicator can be something else, e.g. a keyword "inline"
+// I am pronouncing '*' as "contents of"
+struct ByValue {
+    *Complex c;         // c is inlined, full 16 bytes into ByValue
+};
+print(new ByValue.c.y); // x,y inlined into ByValue, no extra memory load
+
+// Mixing Refs and Struct Values.  Basically, a ref can be converted
+// to a value by taking the "contents of" the ref, and values cannot
+// be *converted* to a ref, although they can be copied over a ref.
+ref. c =  val.c; // Error, mixing refs and values
+ref.*c =  val.c; // Allowed, whole structure copy.  Does not allocate, requires ref.c not-null
+val. c =  ref.c; // Error, mixing refs and values
+val. c = *ref.c; // Allowed, whole structure copy
+ref. c =  ref.c; // Allowed, pointer copy
+val. c =  val.c; // Allowed, whole structure copy.
+val *c =  val.c; // Error, cannot take "contents of" a value
+
+// Alternative syntax, to avoid the "contents of" being on LHS and field applying to being on RHS:
+ref.c = val.*c; // Assign into ref.c the "contents of" val.c
+
+// Arrays of inlined structures
+var ary = new *Complex[99]; // Array of 99 Complex objects, inlined
+
+// Calling methods has the same syntax
+ref.c.len();
+val.c.len();
+
+// Function arguments use the same typing, so can pass-by-value
+val math.sin = { Complex *c -> ... }; // Passes a complex by value
+math.sin(ref.*c); // Requires de-reference to pass by value
+math.sin(val. c); // Pass by value
+
+```
+
+
 
 ## Unifying Structs and Arrays
 
@@ -347,54 +403,6 @@ gstr *prize3 = "bronze";
 ### Main becomes `val main = { str[] args -> ...}`
 
 
-### Allow structs to inline
-
-This is a name-space change only, you cannot take the address of the internal
-struct without entirely consuming its lifetime.  No "escaping".
-
-```java
-// 2 64-bit words, no other overheads
-struct Complex { f64 x,y; var len = { ->Math.sqrt(x*x+y*y); }; };
-
-// Current Simple rules: always by-reference
-struct ByRef {
-    Complex c; // 4-byte pointer to a Complex
-};
-print(new ByRef.c.y); // Lookup requires 1 extra memory load from ref to c
-
-// New behavior: by value (inlining a struct)
-// The '*' syntax indicator can be something else, e.g. a keyword "inline"
-// I am pronouncing '*' as "contents of"
-struct ByValue {
-    *Complex c; // c is inlined, full 16 bytes into ByValue
-};
-print(new ByValue.c.y); // x,y inlined into ByValue, no extra memory load
-
-// Mixing Refs and Struct Values
-ref.c =  val.c; // Error, mixing refs and values
-ref.c = *val.c; // Allowed, whole structure copy.  Does not allocate, requires ref.c not-null
-val.c =  ref.c; // Error, mixing refs and values
-val.c = *ref.c; // Allowed, whole structure copy
-ref.c =  ref.c; // Allowed, pointer copy
-val.c = *val.c; // Allowed, whole structure copy.
-val.c =  val.c; // Allowed, whole structure copy, same as above, convenience
-
-// Alternative syntax, to avoid the "contents of" being on LHS and field applying to being on RHS:
-ref.c = val.*c; // Assign into ref.c the "contents of" val.c
-
-// Arrays of inlined structures
-var ary = new *Complex[99]; // Array of 99 Complex objects, inlined
-
-// Calling methods has the same syntax
-ref.c.len();
-val.c.len();
-
-// Function arguments use the same typing, so can pass-by-value
-val math.sin = { Complex *c -> ... }; // Passes a complex by value
-math.sin(*ref.c); // Requires de-reference to pass by value
-math.sin( val.c); // Pass by value
-
-```
 
 ### RoadMap for other chapters
 
@@ -405,11 +413,11 @@ Default parser for-loop construction, or partial peel.
     `for( init; test; next ) body`
 becomes:
 ```java
-{ init;
+{ init;       // Normal scope entry to bound lifetime of index variable
 if( !test ) { // Zero-trip count test
     do {
         body;
         next;
     } while( test ); // Exit test at loop bottom by default
-} }
+} };
 ```
\ No newline at end of file
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