From 9175a98a2a1f8defcc3c103422d530eb2ae083de Mon Sep 17 00:00:00 2001
From: Sergiu Ivanov <sivanov@colimite.fr>
Date: Sun, 12 Mar 2023 20:54:25 +0100
Subject: [PATCH] Add hash-replace-keys/ordered.

---
 scribblings/utils.scrbl | 14 ++++++++++++++
 utils.rkt               | 15 ++++++++++++++-
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/scribblings/utils.scrbl b/scribblings/utils.scrbl
index 0dad8ee..d04fc8c 100644
--- a/scribblings/utils.scrbl
+++ b/scribblings/utils.scrbl
@@ -486,6 +486,20 @@ hash table orders them for @racket[hash-map].
 (hash->list/ordered #hash((b . 1) (a . 1)))
 ]}
 
+@defproc[(hash-replace-keys/ordered [ht (Immutable-HashTable (K1 V))]
+				    [new-keys (Listof K2)])
+				    (Immutable-HashTable K2 V)]{
+
+Replaces the keys in @racket[ht] by the keys in @racket[new-keys].
+
+The key-value pairs of the hash table @racket[ht] are processed in the
+order produced by @racket[hash-map] with @racket[#:try-order?] set to
+@racket[#t].
+
+@ex[
+(hash-replace-keys/ordered (hash 'a 1 'b 2) '(x y))
+]}
+
 @defproc[(multi-split-at [lists (Listof (Listof a))]
 			 [pos Integer])
 			 (Values (Listof (Listof a)) (Listof (Listof a)))]{
diff --git a/utils.rkt b/utils.rkt
index 2180567..8faf33d 100644
--- a/utils.rkt
+++ b/utils.rkt
@@ -15,7 +15,7 @@
  read-org-variable-mapping unorgv read-symbol-list drop-first-last
  list-sets->list-strings pretty-print-set pretty-print-set-sets
  update-vertices/unweighted update-graph dotit collect-by-key
- collect-by-key/sets ht-values/list->set hash->list/ordered
+ collect-by-key/sets ht-values/list->set hash->list/ordered hash-replace-keys/ordered
  multi-split-at lists-transpose append-lists in-random cartesian-product-2/stream
  cartesian-product/stream boolean-power boolean-power/stream any->01
  01->boolean
@@ -498,6 +498,19 @@
     (check-equal? (hash->list/ordered #hash((b . 1) (a . 1)))
                   '((a . 1) (b . 1)))))
 
+(: hash-replace-keys/ordered (All (K1 K2 V) (-> (Immutable-HashTable K1 V) (Listof K2)
+                                                (Immutable-HashTable K2 V))))
+(define (hash-replace-keys/ordered ht new-keys)
+  (make-immutable-hash (map (λ ([new-k : K2] [pair : (Pairof K1 V)])
+                              (cons new-k (cdr pair)))
+                            new-keys
+                            (hash->list/ordered ht))))
+
+(module+ test
+  (test-case "hash-replace-keys/ordered"
+    (check-equal? (hash-replace-keys/ordered (hash 'a 1 'b 2) '(x y))
+                  '#hash((x . 1) (y . 2)))))
+
 (: multi-split-at (All (a) (-> (Listof (Listof a)) Integer
                                (Values (Listof (Listof a)) (Listof (Listof a))))))
 (define (multi-split-at lists pos)