From e90aed9d1b435a401ed3b9de58b7ea8677db1365 Mon Sep 17 00:00:00 2001 From: Jan Nieuwenhuizen Date: Sat, 15 Dec 2018 12:56:15 +0100 Subject: [PATCH] mes: assq-ref, assoc-ref: Support alist == #f. * mes/module/mes/scm.mes (assq-ref): Support alist == #f. (assoc-ref): Likewise. --- mes/module/mes/scm.mes | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/mes/module/mes/scm.mes b/mes/module/mes/scm.mes index c4d78035..20243ff7 100644 --- a/mes/module/mes/scm.mes +++ b/mes/module/mes/scm.mes @@ -101,17 +101,19 @@ alist)))) (define (assq-ref alist key) - (let ((entry (assq key alist))) - (if entry (cdr entry) - #f))) + (and alist + (let ((entry (assq key alist))) + (if entry (cdr entry) + #f)))) (define assv assq) (define assv-ref assq-ref) (define (assoc-ref alist key) - (let ((entry (assoc key alist))) - (if entry (cdr entry) - #f))) + (and (pair? alist) + (let ((entry (assoc key alist))) + (if entry (cdr entry) + #f)))) (define (assoc-set! alist key value) (let ((entry (assoc key alist)))