correct slight naivete

sugar/private/syntax-utils.rkt

@@ -16,14 +16,22 @@
 ;; convert calling pattern to form (id contract body-exp)
 ;; hoist contract out of lambda-exp entirely
 (define-syntax-rule (lambdafy-with-contract stx)
-  (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)))])
-    ;; lambda-exp = #'(lambda args body-exp (... ...))
-    #'(id contract (lambda args body-exp (... ...)))))
+  (syntax-case stx ()
+    [(_ id contract lambda-exp)
+     ;; `normalize-definition` can't handle the `define/contract` pattern of three expressions 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))])
+       #'(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)))])
+       ;; lambda-exp = #'(lambda args body-exp (... ...))
+       #'(id contract (lambda args body-exp (... ...))))]))
 
 
 ;; convert calling pattern to form (id body-exp)
 (define-syntax-rule (lambdafy stx)
   (with-syntax ([(id lambda-exp) (let-values ([(id-stx body-exp-stx) (normalize-definition stx (datum->syntax stx 'λ) #t #t)])
-                                 (list id-stx body-exp-stx))])
+                                   (list id-stx body-exp-stx))])
     #'(id lambda-exp)))

sugar/test/main.rkt

@@ -78,6 +78,18 @@
  (check-equal? (safe:dps-f 1 #:y 0 2 3) 6)
  (check-exn exn:fail? (λ _ (safe:dps-f 'foo)))
  
+ (module dpsb racket/base
+   (require sugar/define)
+   (define+provide+safe dpsb-f 
+     ((integer?) (#:y integer?) #:rest (listof integer?) . ->* . integer?)
+     (λ(x #:y [y 42] . zs) (apply + x y zs))))
+ 
+ (require 'dpsb)
+ (check-equal? (dpsb-f 1 #:y 0 2 3) 6)
+ (require (prefix-in safe: (submod 'dpsb safe)))
+ (check-equal? (safe:dpsb-f 1 #:y 0 2 3) 6)
+ (check-exn exn:fail? (λ _ (safe:dpsb-f 'foo)))
+ 
  (module ps racket/base
    (require "../define.rkt")
    (provide+safe [ps-f ((integer?) (#:y integer?) #:rest (listof integer?) . ->* . integer?)])