(cond-expand
 (chicken) ;; Use embedded type declarations
 ;; Add cases for other Scheme implementations to translate type declarations here.
 ;; == Non so far. ==
 ;; == End of implementation specific type declaration handling. ==
 ;; Ignore embedded type declarations on other implementations.
 ;; Add Scheme implementations here having define-macro but no
 ;; define-syntax and no support for type declarations
 ((or rscheme)
  (define-macro (: name . typedeclaration) `(begin)))
 ;; Ignore type declarations on Scheme other implementations.
 (else
  (define-syntax :
    (syntax-rules () ((_ . spec) (begin #f))))))