From c2cb624e422922fb2b779820480c85185d20843c Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonygarnockjones@gmail.com>
Date: Mon, 30 Apr 2018 10:04:33 +0100
Subject: [PATCH] Another small speed bump from using hash-for-each over
 in-hash-keys

---
 syndicate/skeleton.rkt | 49 +++++++++++++++++++++++-------------------
 1 file changed, 27 insertions(+), 22 deletions(-)

diff --git a/syndicate/skeleton.rkt b/syndicate/skeleton.rkt
index bbae7cf..aad57f9 100644
--- a/syndicate/skeleton.rkt
+++ b/syndicate/skeleton.rkt
@@ -117,17 +117,19 @@
   (match-define (skeleton-interest _desc cs cv vs h _cleanup) i)
   (define (make-matched-constant)
     (define assertions (make-hash))
-    (for [(a (in-hash-keys (skeleton-continuation-cache c)))
-          #:when (equal? (apply-projection a cs) cv)]
-      (hash-set! assertions a #t))
+    (hash-for-each (skeleton-continuation-cache c)
+                   (lambda (a _)
+                     (when (equal? (apply-projection a cs) cv)
+                       (hash-set! assertions a #t))))
     (skeleton-matched-constant assertions (make-hash)))
   (define cvt (hash-ref! (skeleton-continuation-table c) cs make-hash))
   (define sc (hash-ref! cvt cv make-matched-constant))
   (define (make-accumulator)
     (define cache (make-bag))
-    (for [(a (in-hash-keys (skeleton-matched-constant-cache sc)))]
-      (define vars (apply-projection a vs))
-      (bag-change! cache vars 1))
+    (hash-for-each (skeleton-matched-constant-cache sc)
+                   (lambda (a _)
+                     (define vars (apply-projection a vs))
+                     (bag-change! cache vars 1)))
     (skeleton-accumulator cache (make-hasheq)))
   (define acc (hash-ref! (skeleton-matched-constant-table sc) vs make-accumulator))
   (hash-set! (skeleton-accumulator-handlers acc) h #t)
@@ -181,8 +183,10 @@
        (define (make-skeleton-node-with-cache)
          (define unfiltered (skeleton-continuation-cache (skeleton-node-continuation sk)))
          (define filtered (make-hash))
-         (for [(a (in-hash-keys unfiltered)) #:when (subterm-matches-class? a path class)]
-           (hash-set! filtered a #t))
+         (hash-for-each unfiltered
+                        (lambda (a _)
+                          (when (subterm-matches-class? a path class)
+                            (hash-set! filtered a #t))))
          (make-empty-skeleton/cache filtered))
        (define next (hash-ref! table class make-skeleton-node-with-cache))
        (walk-edge! (update-path path pop-count 0) next 0 0 pieces)]
@@ -211,14 +215,15 @@
     (match-define (skeleton-node continuation edges) sk)
 
     (modify-skcont! continuation term0)
-    (for [((constant-proj key-proj-handler) (in-hash (skeleton-continuation-table continuation)))]
-      (define constants (apply-projection term0 constant-proj))
-      (define proj-handler (hash-ref key-proj-handler constants #f))
-      (when proj-handler
-        (modify-skconst! proj-handler term0)
-        (for [((variable-proj acc) (in-hash (skeleton-matched-constant-table proj-handler)))]
-          (define variables (apply-projection term0 variable-proj))
-          (modify-skacc! acc variables term0))))
+    (hash-for-each (skeleton-continuation-table continuation)
+                   (lambda (constant-proj key-proj-handler)
+                     (define constants (apply-projection term0 constant-proj))
+                     (define proj-handler (hash-ref key-proj-handler constants #f))
+                     (when proj-handler
+                       (modify-skconst! proj-handler term0)
+                       (for [((variable-proj acc) (in-hash (skeleton-matched-constant-table proj-handler)))]
+                         (define variables (apply-projection term0 variable-proj))
+                         (modify-skacc! acc variables term0)))))
 
     (for [(edge (in-list edges))]
       (match-define (cons (skeleton-selector pop-count index) table) edge)
@@ -245,8 +250,8 @@
 (define (add-term-to-skacc! skacc vars _term)
   (match (bag-change! (skeleton-accumulator-cache skacc) vars 1)
     ['absent->present
-     (for [(handler (in-hash-keys (skeleton-accumulator-handlers skacc)))]
-       (apply handler '+ vars))]
+     (hash-for-each (skeleton-accumulator-handlers skacc)
+                    (lambda (handler _) (apply handler '+ vars)))]
     ;; 'present->absent and 'absent->absent absurd
     ['present->present
      (void)]))
@@ -267,8 +272,8 @@
   (if (bag-member? cache vars)
       (match (bag-change! cache vars -1)
         ['present->absent
-         (for [(handler (in-hash-keys (skeleton-accumulator-handlers skacc)))]
-           (apply handler '- vars))]
+         (hash-for-each (skeleton-accumulator-handlers skacc)
+                        (lambda (handler _) (apply handler '- vars)))]
         ;; 'absent->absent and 'absent->present absurd
         ['present->present
          (void)])
@@ -287,8 +292,8 @@
                     void
                     void
                     (lambda (skacc vars _term)
-                      (for [(handler (in-hash-keys (skeleton-accumulator-handlers skacc)))]
-                        (apply handler '! vars)))))
+                      (hash-for-each (skeleton-accumulator-handlers skacc)
+                                     (lambda (handler _) (apply handler '! vars))))))
 
 ;; TODO: avoid repeated descent into `term` by factoring out prefixes of paths in `proj`
 (define (apply-projection term proj)