;;; This implements the pattern binding rule.
 
 (define (apply-pattern-binding-rule? decls)
  (not
   (every (lambda (decl)
 	   (or (function-binding? decl)
 	       (simple-pattern-binding-with-signature? decl)))
 	 decls)))
 
 (define (function-binding? decl)
   (let ((defs (valdef-definitions decl)))
     (not (null? (single-fun-def-args (car defs))))))
 
 (define (simple-pattern-binding-with-signature? decl)
   (let ((lhs (valdef-lhs decl))
 	(defs (valdef-definitions decl)))
     (and (is-type? 'var-pat lhs)
 	 (null? (single-fun-def-args (car defs)))
 	 (not (eq? (var-signature (var-ref-var (var-pat-var lhs))) '#f)))))
 
 (define (do-pattern-binding-rule decls necessary-tyvars ng-list)
   (setf ng-list (append necessary-tyvars ng-list))
   (find-exported-pattern-bindings decls)
   ng-list)
 
 (define (find-exported-pattern-bindings decls)
   (dolist (decl decls)
     (dolist (var-ref (collect-pattern-vars (valdef-lhs decl)))
      (let ((var (var-ref-var var-ref)))
       (when (def-exported? var)
 	(recoverable-error 'exported-pattern-binding
            "Can't export pattern binding of ~A~%" var-ref))
       (when (not (eq? (var-signature var) '#f))
          (recoverable-error 'entire-group-needs-signature
            "Variable ~A signature declaration ignored~%" var-ref))))))