clarifications

sugar/private/syntax-utils.rkt

@@ -1,6 +1,6 @@
 #lang racket/base
 (require (for-syntax racket/base) syntax/define)
-(provide (all-defined-out))
+(provide (except-out (all-defined-out) values->list))
 
 
 (define-syntax-rule (require+provide/safe modname ...)
@@ -13,21 +13,28 @@
         (provide (all-from-out (submod modname safe))))) ...))
 
 
+(define-syntax (values->list stx)
+  (syntax-case stx ()
+    [(_ values-expr) #'(call-with-values (λ () values-expr) list)]))
+
 ;; convert calling pattern to form (id contract body-exp)
 ;; hoist contract out of lambda-exp entirely
 (define-syntax-rule (lambdafy-with-contract stx)
   (syntax-case stx ()
-    [(_ id contract lambda-exp)
-     ;; `normalize-definition` can't handle the `define/contract` pattern of three expressions after the `define`.
+    
+    [(_ id-exp contract lambda-exp) ; matches exactly three args after `define`
+     ;; `normalize-definition` can't handle the acceptable `define/contract` pattern of id, contract, lambda exp after the `define`.
      ;; so extract the contract, and then put id & lambda-exp back together, and let `normalize-definition` destructure as usual.
-     (with-syntax ([(new-id new-lambda-exp) (let-values ([(id-stx body-exp-stx) (normalize-definition #'(_ id lambda-exp) (datum->syntax stx 'λ) #t #t)])
-                                      (list id-stx body-exp-stx))])
+     (with-syntax ([(new-id new-lambda-exp) (values->list (normalize-definition #'(_ id-exp lambda-exp) (datum->syntax #'id-exp 'λ) #t #t))])
        #'(new-id contract new-lambda-exp))]
-    [else
-     (with-syntax ([(id (lambda args contract body-exp (... ...))) (let*-values ([(id-stx rhs-exp-stx) (normalize-definition stx (datum->syntax stx 'λ) #t #t)])
-                                                                     (list id-stx (syntax->list rhs-exp-stx)))])
+    
+    [(_ id-exp maybe-contract body-exp (... ...)) ; matches two, or four or more
+     (with-syntax ([(id (lambda args contract body-exp (... ...))) (values->list (normalize-definition stx (datum->syntax #'id-exp 'λ) #t #t))])
        ;; lambda-exp = #'(lambda args body-exp (... ...))
-       #'(id contract (lambda args body-exp (... ...))))]))
+       #'(id contract (lambda args body-exp (... ...))))]
+    
+    [else ; matches zero or one arugments 
+     (error 'define-macro "not enough arguments")]))
 
 
 ;; convert calling pattern to form (id body-exp)