From 666ad23844be33141f7c986de3b83f035db4b95a Mon Sep 17 00:00:00 2001
From: Marshall Lochbaum <mwlochbaum@gmail.com>
Date: Mon, 15 Feb 2021 17:51:17 -0500
Subject: Reference implementation and commentary for Group length extension

---
 spec/reference.bqn | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

(limited to 'spec/reference.bqn')

diff --git a/spec/reference.bqn b/spec/reference.bqn
index 288fdc39..988bfb51 100644
--- a/spec/reference.bqn
+++ b/spec/reference.bqn
@@ -383,11 +383,16 @@ Group←{
   𝕨↩Pair∘ToArray⍟(2>≡)𝕨
   ! 1==𝕨
   {!∧´Int¨𝕩⋄!∧´¯1≤𝕩}∘⥊¨𝕨
-  n←+´=¨𝕨
+  n←+´r←=¨𝕨
   ! n≤=𝕩
-  ! (∾≢⌜𝕨)≡n↑≢𝕩
-  𝕨↩⥊¨𝕨 ⋄ 𝕩↩((≠¨𝕨)∾n↓≢𝕩)⥊𝕩
-  (𝕨⊸=/𝕩˙)¨↕1+¯1⌈´¨𝕨
+  ld←(∾≢⌜𝕨)-n↑≢𝕩
+  ! ∧´(0⊸≤∧≤⟜(r/1=r))ld
+  dr←r⌊(0»+`r)⊏ld∾⟨0⟩
+  s←dr⊣◶⟨0,¯1⊸⊑⟩¨𝕨
+  𝕨↩dr(⥊¯1⊸↓⍟⊣)¨𝕨
+  s⌈↩1+¯1⌈´¨𝕨
+  𝕩↩((≠¨𝕨)∾n↓≢𝕩)⥊𝕩
+  (𝕨⊸=/𝕩˙)¨↕s
 }
 GroupInds←{
   ! 1==𝕩
-- 
cgit v1.2.3