From 53d0a67e96f138bc9d57e0f4085c37e5d230d2ee Mon Sep 17 00:00:00 2001 From: Tony Garnock-Jones Date: Wed, 28 May 2014 16:31:05 -0400 Subject: [PATCH] Permit function to return #f in transition-bind --- minimart/core.rkt | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/minimart/core.rkt b/minimart/core.rkt index 31fac58..3727c01 100644 --- a/minimart/core.rkt +++ b/minimart/core.rkt @@ -100,8 +100,9 @@ (define (transition-bind k t0) (match-define (transition state0 actions0) t0) - (match-define (transition state1 actions1) (k state0)) - (transition state1 (cons actions0 actions1))) + (match (k state0) + [(transition state1 actions1) (transition state1 (cons actions0 actions1))] + [#f t0])) (define (sequence-transitions t0 . steps) (foldl transition-bind t0 steps))