[Guile-commits] 05/06: Add record-type-parent definition.

[Andy Wingo]

wingo pushed a commit to branch master
in repository guile.

commit 1ae0f8d49043cc8c7bc4a31966ea078747edd490
Author: Andy Wingo <address@hidden>
Date:   Tue Oct 29 10:34:35 2019 +0100

    Add record-type-parent definition.
    
    * module/ice-9/boot-9.scm (record-type-parent): New definition.
---
 module/ice-9/boot-9.scm | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/module/ice-9/boot-9.scm b/module/ice-9/boot-9.scm
index d310a13..db21c69 100644
--- a/module/ice-9/boot-9.scm
+++ b/module/ice-9/boot-9.scm
@@ -1234,6 +1234,11 @@ VALUE."
   (unless (record-type? rtd)
     (error 'not-a-record-type rtd))
   (struct-ref rtd (+ 4 vtable-offset-user)))
+(define (record-type-parent rtd)
+  (let* ((parents (record-type-parents rtd))
+         (nparents (vector-length parents)))
+    (and (not (zero? nparents))
+         (vector-ref parents (1- nparents)))))
 
 (define (record-type-mutable-fields rtd)
   (unless (record-type? rtd)