<HTML><BODY>#lang racket (require (for-syntax racket racket/struct-info)) (struct foo (a b)) (set! foo-a (let ([old foo-a]) (λ (x) (displayln x) (old x)))) (define t (foo 1 2)) (displayln "Before change") (match t [(foo a b) a]) (let-syntax ([foo (extract-struct-info (syntax-local-value #'foo))]) (displayln "After change") (match t [(foo a b) a])) Gives: Before change 1 After change #<foo> 1 So, resetting foo to the same struct-info enable calling modified foo-a. But why? Besides, if it is inevitable, how to redefine (like set!) the syntax? -- Roman Klochkov</BODY></HTML>