From 43d963285945e0b5d5aafd7a96f880dc0b76c34b Mon Sep 17 00:00:00 2001
From: Jack Firth <jackhfirth@gmail.com>
Date: Wed, 30 Mar 2022 02:09:32 -0700
Subject: [PATCH] Use `hash-update!` where possible

---
 parser-tools/private-lex/deriv.rkt | 6 +-----
 parser-tools/private-yacc/lr0.rkt  | 2 +-
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/parser-tools/private-lex/deriv.rkt b/parser-tools/private-lex/deriv.rkt
index 77b7488..7f597e3 100644
--- a/parser-tools/private-lex/deriv.rkt
+++ b/parser-tools/private-lex/deriv.rkt
@@ -263,11 +263,7 @@
                                        (set! new-state? #t)
                                        (state new-re (get-state-number))))]
                    [new-all-states (if new-state? (cons new-state all-states) all-states)])
-              (hash-set! transitions 
-                         s
-                         (cons (cons c new-state)
-                               (hash-ref transitions s
-                                         '())))
+              (hash-update! transitions s (λ (v) (cons (cons c new-state) v)) '())
               (cond
                 [new-state?
                  (loop old-states (cons new-state new-states) new-all-states (cdr cs))]
diff --git a/parser-tools/private-yacc/lr0.rkt b/parser-tools/private-yacc/lr0.rkt
index 193cd24..ce504d6 100644
--- a/parser-tools/private-yacc/lr0.rkt
+++ b/parser-tools/private-yacc/lr0.rkt
@@ -59,7 +59,7 @@
 (define (reverse-assoc assoc)
   (define reverse-hash (make-hash))
   (define (hash-table-add! ht k v)
-    (hash-set! ht k (cons v (hash-ref ht k '()))))
+    (hash-update! ht k (λ (v) (cons v v)) '()))
   (for ([trans-key/kernel (in-list assoc)])
        (define tk (car trans-key/kernel))
        (hash-table-add! reverse-hash