oke.

demo/js-usecases.rkt

@@ -2,18 +2,80 @@
 
 (require "../main.rkt")
 
-(provide generated-js)
+(provide usecase-random-number
+         usecase-unique-values
+         usecase-array-at
+         usecase-sum-to
+         usecase-make-adder
+         usecase-set-html
+         all-js-usecases
+         show-js-usecases
+         write-js-usecases-file)
 
-(define generated-js
+;; Use case 01: generate a random integer between 1 and 5.
+(define usecase-random-number
   (js
-   (define answer 42)
-   (define (square x)
-     (return (* x x)))
-   (define (sum-to n)
+   (define (randomBetween1And5)
+     (return (+ (send Math floor (* (send Math random) 5)) 1)))))
+
+;; Use case 02: get unique values from an array with duplicates using Set.
+(define usecase-unique-values
+  (js
+   (define (uniqueValues xs)
+     (return (send Array from (new Set xs))))))
+
+;; Use case 03: indexed array access with js-ref.
+(define usecase-array-at
+  (js
+   (define (arrayAt xs i)
+     (return (js-ref xs i)))))
+
+;; Use case 04: named let as a loop.  The branch that leaves the loop uses an
+;; explicit return, because js-maker 3 is statement-oriented.
+(define usecase-sum-to
+  (js
+   (define (sumTo n)
      (let loop ([i 0] [acc 0])
        (if (> i n)
            (return acc)
            (loop (+ i 1) (+ acc i)))))))
 
+;; Use case 05: return a JavaScript function value.
+(define usecase-make-adder
+  (js
+   (define (makeAdder x)
+     (return (lambda (y)
+               (return (+ x y)))))))
+
+;; Use case 06: small DOM setter.  It uses send, js-dot and set!.
+(define usecase-set-html
+  (js
+   (define (setHtml id html)
+     (let ([el (send document getElementById id)])
+       (set! (js-dot el innerHTML) html)
+       (return (js-dot el innerHTML))))))
+
+(define all-js-usecases
+  `((random-number . ,usecase-random-number)
+    (unique-values . ,usecase-unique-values)
+    (array-at . ,usecase-array-at)
+    (sum-to . ,usecase-sum-to)
+    (make-adder . ,usecase-make-adder)
+    (set-html . ,usecase-set-html)))
+
+(define (show-js-usecases)
+  (for ([entry (in-list all-js-usecases)])
+    (displayln (format "// ~a" (car entry)))
+    (displayln (cdr entry))
+    (newline)))
+
+(define (write-js-usecases-file [path "demo/js-usecases.generated.js"])
+  (call-with-output-file path #:exists 'replace
+    (lambda (out)
+      (for ([entry (in-list all-js-usecases)])
+        (displayln (format "// ~a" (car entry)) out)
+        (displayln (cdr entry) out)
+        (newline out)))))
+
 (module+ main
-  (display generated-js))
+  (show-js-usecases))