better racket example support

examples/test_code/example.rkt

@@ -1,5 +1,11 @@
 #lang racket
 
+;; ============================================
+;; Example Racket file for g3 code search tests
+;; ============================================
+
+;; --- Basic Functions ---
+
 (define (greet name)
   (printf "Hello, ~a!\n" name))
 
@@ -11,14 +17,116 @@
       1
       (* n (factorial (- n 1)))))
 
+;; --- Variable Definitions ---
+
+(define pi 3.14159)
+(define greeting "Hello, World!")
+
+;; --- Structs ---
+
 (struct person (name age) #:transparent)
+(struct point (x y) #:transparent)
 
 (define (person-greet p)
   (printf "Hello, I'm ~a\n" (person-name p)))
 
-(greet "World")
-(displayln (add 5 3))
-(displayln (factorial 5))
+;; --- Pattern Matching ---
 
-(define alice (person "Alice" 30))
-(person-greet alice)
+(define (describe-list lst)
+  (match lst
+    ['() "empty"]
+    [(list x) (format "singleton: ~a" x)]
+    [(list x y) (format "pair: ~a, ~a" x y)]
+    [_ "many elements"]))
+
+(define (point-quadrant p)
+  (match p
+    [(point (? positive?) (? positive?)) 'first]
+    [(point (? negative?) (? positive?)) 'second]
+    [(point (? negative?) (? negative?)) 'third]
+    [(point (? positive?) (? negative?)) 'fourth]
+    [_ 'origin-or-axis]))
+
+;; --- Lambda and Higher-Order Functions ---
+
+(define double (lambda (x) (* x 2)))
+(define triple (λ (x) (* x 3)))
+
+(define (apply-twice f x)
+  (f (f x)))
+
+;; --- Let Bindings ---
+
+(define (circle-area radius)
+  (let ([pi 3.14159])
+    (* pi radius radius)))
+
+(define (swap-and-sum a b)
+  (let* ([temp a]
+         [a b]
+         [b temp])
+    (+ a b)))
+
+;; --- For Loops ---
+
+(define (sum-squares n)
+  (for/sum ([i (in-range 1 (add1 n))])
+    (* i i)))
+
+(define (collect-evens n)
+  (for/list ([i (in-range n)]
+             #:when (even? i))
+    i))
+
+(define (matrix-coords rows cols)
+  (for*/list ([r (in-range rows)]
+              [c (in-range cols)])
+    (cons r c)))
+
+;; --- Macros ---
+
+(define-syntax-rule (swap! x y)
+  (let ([tmp x])
+    (set! x y)
+    (set! y tmp)))
+
+(define-syntax-rule (unless condition body ...)
+  (when (not condition)
+    body ...))
+
+;; --- Contracts ---
+
+(define/contract (safe-divide x y)
+  (-> number? (and/c number? (not/c zero?)) number?)
+  (/ x y))
+
+(define/contract (non-negative-add a b)
+  (-> (>=/c 0) (>=/c 0) (>=/c 0))
+  (+ a b))
+
+;; --- Require and Provide ---
+
+(require racket/string)
+(require racket/list)
+
+;; --- Module ---
+
+(module+ test
+  (require rackunit)
+  
+  (check-equal? (add 2 3) 5)
+  (check-equal? (factorial 5) 120)
+  (check-equal? (sum-squares 3) 14)
+  (check-equal? (describe-list '()) "empty")
+  (check-equal? (describe-list '(1)) "singleton: 1"))
+
+(module+ main
+  (greet "World")
+  (displayln (add 5 3))
+  (displayln (factorial 5))
+  
+  (define alice (person "Alice" 30))
+  (person-greet alice)
+  
+  (displayln (sum-squares 10))
+  (displayln (collect-evens 10)))