Refactor let to define where applicable

Racke style guide:
https://docs.racket-lang.org/style/Choosing_the_Right_Construct.html#%28part._.Definitions%29

src/config.rkt

@@ -24,7 +24,8 @@
   (make-hasheq
    (append
     default-config
-    (with-handlers ([exn:fail:filesystem:errno?
+    (with-handlers
+      ([exn:fail:filesystem:errno?
         (λ (exn)
           (begin0
               '()
@@ -34,16 +35,17 @@
           (begin0
               '()
             (displayln "note: config file empty or missing [] section, using defaults")))])
-      (let ([l (hash->list
+      (define l
+        (hash->list
          (hash-ref
           (ini->hash
            (call-with-input-file path-config
              (λ (in)
                (read-ini in))))
-                 '||))])
+          '||)))
       (begin0
           l
-              (printf "note: ~a items loaded from config file~n" (length l))))))))
+        (printf "note: ~a items loaded from config file~n" (length l)))))))
 
 (when (config-true? 'debug)
   (printf "config: ~v~n" config))

src/page-category.rkt

@@ -33,11 +33,11 @@
          (ul (@ (class "my-category-list"))
              ,@(map
                 (λ (result)
-                  (let* ([title (jp "/title" result)]
+                  (define title (jp "/title" result))
-                         [page-path (regexp-replace* #rx" " title "_")])
+                  (define page-path (regexp-replace* #rx" " title "_"))
                   `(li
                     (a (@ (href ,(format "/~a/wiki/~a" wikiname page-path)))
-                         ,title))))
+                       ,title)))
                 members)))))
 
 (define (page-category req)

src/page-wiki.rkt

@@ -42,7 +42,8 @@
                 (div (@ (class "collapsible-content"))
                      (p "Another page link: "
                         (a (@ (data-test-wikilink) (href "https://test.fandom.com/wiki/Another_Page") (title "Another Page"))
-                           "Another Page"))))))))
+                           "Another Page"))))
+           (iframe (@ (src "https://example.com/iframe-src")))))))
 
 (define (preprocess-html-wiki html)
   (define (rr* find replace contents)
@@ -95,10 +96,10 @@
         return-no-element]
        ; display a link instead of an iframe
        [(eq? element-type 'iframe)
-        (let ([src (car (dict-ref attributes 'src null))])
+        (define src (car (dict-ref attributes 'src null)))
         `(a
           ((class "iframe-alternative") (href ,src))
-            (,(format "Embedded media: ~a" src))))]
+          (,(format "Embedded media: ~a" src)))]
        [#t
         (list element-type
               ;; attributes
@@ -193,7 +194,13 @@
                                        ((query-selector
                                          (λ (t a c) (dict-has-key? a 'data-test-collapsesection))
                                          transformed))))
-                "collapsible collapsetoggle-inline"))
+                "collapsible collapsetoggle-inline")
+  ; check that iframes are gone
+  (check-false ((query-selector (λ (t a c) (eq? t 'iframe)) transformed)))
+  (check-equal? (let* ([alternative ((query-selector (λ (t a c) (has-class? "iframe-alternative" a)) transformed))]
+                       [link ((query-selector (λ (t a c) (eq? t 'a)) alternative))])
+                  (get-attribute 'href (bits->attributes link)))
+                "https://example.com/iframe-src"))
 
 (define (page-wiki req)
   (define wikiname (path/param-path (first (url-path (request-uri req)))))

src/reloadable.rkt

@@ -70,7 +70,7 @@
   (define real-error-port (thread-receive))
   (say-loading-once! real-error-port)
   (let loop ()
-    (let ([line (read-line i)])
+    (define line (read-line i))
     (cond
       [(eof-object? line)
        (void)]
@@ -79,7 +79,7 @@
        (loop)]
       [#t
        (displayln line real-error-port)
-         (loop)]))))
+       (loop)])))
 
 ;; Only to be called from reloader-main
 (define (do-reload!)

src/xexpr-utils.rkt

@@ -100,20 +100,22 @@
   (check-false (element-is-content? '(@ (alt "Cute cat."))))
   (check-true (element-is-content? "hi")))
 
+; get the actual attributes, leaving out the @ signs
 (define (xattributes->attributes xattrs)
   (filter pair? xattrs))
 
 (define (bits->attributes bits)
+ ; (append) is a clean and general approach to finding and combining any attributes
   (xattributes->attributes (apply append (filter element-is-xattributes? bits))))
 (module+ test
   (check-equal? (bits->attributes demo-attributes)
                 '((title "Inside joke.") (style "color: blue"))))
 
 (define (get-attribute name attributes)
-  (let ([a (assq name attributes)])
+  (define a (assq name attributes))
   (if (pair? a)
       (cadr a)
-        #f)))
+      #f))
 (module+ test
   (check-equal? (get-attribute 'title (bits->attributes demo-attributes)) "Inside joke."))
 
@@ -131,19 +133,16 @@
   (generator
    ()
    (let loop ([element element])
-     (let* ([element-type (car element)]
+     (define element-type (car element))
-            ; (append) is a clean and general approach to finding and combining any attributes
+     (define attributes (bits->attributes (cdr element)))
-            ; (filter pair?) is to get the actual attributes and leaves out the @ signs
+     (define children (filter element-is-element? (cdr element))) ; only recurse through real children
-            [attributes (bits->attributes (cdr element))]
-            ; only recurse through real children
-            [children (filter element-is-element? (cdr element))])
      (cond
        [(equal? element-type '*DECL*) #f]
        [(equal? element-type '@) #f]
        [#t
         (when (selector element-type attributes children)
           (yield element))
-          (for ([child children]) (loop child))])))
+        (for ([child children]) (loop child))]))
   #f))
 (module+ test
   (let ([result (query-selector (attribute-selector 'title "Really.")
@@ -155,12 +154,9 @@
 
 (define (update-tree transformer element)
   (let loop ([element element])
-    (let* ([element-type (car element)]
+    (define element-type (car element))
-           ; (append) is a clean and general approach to finding and combining any attributes
+    (define attributes (bits->attributes (cdr element)))
-           ; (filter pair?) is to get the actual attributes and leaves out the @ signs
+    (define contents (filter element-is-content? (cdr element))) ; provide elements and strings
-           [attributes (bits->attributes (cdr element))]
-           ; provide elements and strings
-           [contents (filter element-is-content? (cdr element))])
     (if (or (equal? element-type '*DECL)
             (equal? element-type '@))
         ; special element, do nothing
@@ -172,7 +168,7 @@
                    (if (pair? attributes) (list (append '(@) attributes)) (list))
                    (map (λ (content)
                           (if (element-is-element? content) (loop content) content))
-                          contents))])))))
+                        contents))]))))
 
 (define (has-class? name attributes)
   (and (member name (string-split (or (get-attribute 'class attributes) "") " ")) #t))