From cbf522459942929f57408525182fb08ab0182b94 Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonygarnockjones@gmail.com>
Date: Sat, 20 Oct 2018 19:13:07 +0100
Subject: [PATCH] Remove superfluous update-path helper

---
 syndicate/HOWITWORKS.md | 8 ++------
 syndicate/skeleton.rkt  | 8 +++-----
 2 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/syndicate/HOWITWORKS.md b/syndicate/HOWITWORKS.md
index 4618ed5..7c14691 100644
--- a/syndicate/HOWITWORKS.md
+++ b/syndicate/HOWITWORKS.md
@@ -275,7 +275,7 @@ cases where handlers are dynamically installed.
         walk-edge h node n_pop n_index (s:shapes) =
           let (n_pop', node') = walk-node h node n_pop n_index s
           let n_index' = n_index + 1
-          let h' = update-path h 1 n_index'
+          let h' = (dropRight h 1) ++ [n_index']
           walk-edge h' node' n_pop' n_index' shapes
 
         walk-node :: H -> Node -> 𝐍 -> 𝐍 -> S -> (𝐍,Node)
@@ -295,13 +295,9 @@ cases where handlers are dynamically installed.
                       classof (project v h) = class }
               edges[selector][class] := ((innercache, {}), {})
           let node' = edges[selector][class]
-          let h' = update-path h 0 0
+          let h' = h ++ [0]
           walk-edge h' node' 0 0 [s_0, ..., s_i]
 
-        update-path :: H -> 𝐍 -> 𝐍 -> H
-        update-path h n_pop n_index =
-          (dropRight h n_pop) ++ [n_index]
-
 **Definition.** The `addHandler` procedure installs into an index an
   event handler callback `f` expecting values matching and captured by
   the given skeleton `k`. It then invokes `f` once for each distinct
diff --git a/syndicate/skeleton.rkt b/syndicate/skeleton.rkt
index 9a0f535..bf88099 100644
--- a/syndicate/skeleton.rkt
+++ b/syndicate/skeleton.rkt
@@ -184,9 +184,6 @@
       [(visibility-restriction p t) (values p t)]
       [other (values #f other)])))
 
-(define (update-path path pop-count index)
-  (append (drop-right path pop-count) (list index)))
-
 (define (extend-skeleton! sk desc)
   (define (walk-node! path sk pop-count index desc)
     (match desc
@@ -212,7 +209,7 @@
                             (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 0 0) next 0 0 pieces)]
+       (walk-edge! (append path '(0)) next 0 0 pieces)]
       [_
        (values pop-count sk)]))
   (define (walk-edge! path sk pop-count index pieces)
@@ -221,7 +218,8 @@
        (values (+ pop-count 1) sk)]
       [(cons p pieces)
        (let-values (((pop-count sk) (walk-node! path sk pop-count index p)))
-         (walk-edge! (update-path path 1 (+ index 1)) sk pop-count (+ index 1) pieces))]))
+         (define next-path (append (drop-right path 1) (list (+ index 1))))
+         (walk-edge! next-path sk pop-count (+ index 1) pieces))]))
   (let-values (((_pop-count sk) (walk-node! '() sk 0 0 desc)))
     sk))