(module qstr-lang mzscheme
  (provide (all-from-except mzscheme #%datum)
           (rename datum #%datum))
  (require "quasistring.ss")
  
  (define-syntax (datum stx)
    (syntax-case stx ()
      [(_ . val)
       (string? (syntax-e #'val))
       #'(qs val)]
      [(_ . any) #'(#%datum . any)])))