[Style] old fixes, can't recall source

collects/scribblings/style/some-performance.scrbl

@@ -21,3 +21,67 @@ If your module is intended as a library, stick to @rkt/base[]. That way
 Conversely, you should use @rkt[] (or even @rkt/gui[]) when you just want a
  convenient language to write some program. The @rkt[] language comes with
  almost all the batteries, and @rkt/gui[] adds the rest of the GUI base.
+
+@; -----------------------------------------------------------------------------
+@section{Macros: Space and Performance}
+
+Macro copy code. Also, Racket is really a tower of macro-implemented
+ languages. Hence, a single line of source code may expand into a rather
+ large core expression. As you and others keep adding macros, even the
+ smallest functions generate huge expressions and consume a lot of space.
+ This kind of space consumption may affect the performance of your project
+ and is therefore to be avoided.
+
+When you design your own macro with a large expansion, try to factor it
+ into a function call that consumes small thunks or procedures.
+
+@compare[
+@racketmod[#:file
+@tt{good}
+racket
+...
+(define-syntax (search->run s)
+  (syntax-parse s
+    [(_ x (e:expr ...)
+        (~datum in)
+        b:expr)
+     #'(sar/λ (list e ...)
+              (λ (x) b))]))
+
+(define (sar/λ l p)
+  (for ((a '())) ((y l))
+    (unless (bad? y)
+      (cons (p y) a))))
+
+(define (bad? x)
+  ... many lines ...)
+...
+]
+@; -----------------------------------------------------------------------------
+@(begin
+#reader scribble/comment-reader
+[racketmod #:file
+@tt{bad}
+racket
+...
+(define-syntax (search->run s)
+  (syntax-parse s
+    [(_ x (e:expr ...)
+       (~datum in)
+       b:expr)
+     #'(begin
+         (define (bad? x)
+           ... many lines ...)
+         (define l
+	   (list e ...))
+         (for ((a '())) ((x l))
+           (unless (bad? x)
+             (cons b a))))]))
+]
+)
+]
+
+As you can see, the macro on the left calls a function with a list of the
+searchable values and a function that encapsulates the body. Every
+expansion is a single function call. In contrast, the macro on the right
+expands to many nested definitions and expressions every time it is used.

collects/scribblings/style/textual.scrbl

@@ -363,7 +363,12 @@ may relax this constraint.
 
 @section{Spaces}
 
-Don't pollute your code with spaces at the end of lines and extraneous blank lines.
+Don't pollute your code with spaces at the end of lines.
+
+If you find yourself breaking long blocks of code with blank lines to aid
+readability, consider refactoring your program to introduce auxiliary
+functions so that you can shorten these long blocks of code. If nothing
+else helps, consider using (potentially) empty comment lines.
 
 @; -----------------------------------------------------------------------------
 @section{End of File}