From b2085b996ecfaeb564d144704fc06bf5f0ba7f75 Mon Sep 17 00:00:00 2001
From: Marshall Lochbaum <mwlochbaum@gmail.com>
Date: Sun, 21 Jun 2020 13:27:27 -0400
Subject: =?UTF-8?q?Add=20negative=20indexing=20to=20=E2=8A=8F=20and=20?=
 =?UTF-8?q?=E2=8A=91?=
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---
 spec/reference.bqn | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

(limited to 'spec/reference.bqn')

diff --git a/spec/reference.bqn b/spec/reference.bqn
index 61e5313a..ea0db2a5 100644
--- a/spec/reference.bqn
+++ b/spec/reference.bqn
@@ -145,8 +145,9 @@ Range←{
 Pick1←{
   ! 1=≠≢𝕨
   ! 𝕨=○≠s←≢𝕩
-  ! ∧´Nat¨𝕨
-  ! ∧´𝕨<s
+  ! ∧´Int¨𝕨
+  ! ∧´𝕨(≥⟜-∧<)s
+  𝕨↩𝕨+s×𝕨<0
   (⥊𝕩)⊑˜0(⊑⟜𝕨+⊑⟜s×⊢)´↕≠𝕨
 }
 Pickd←(∨´IsArray¨)◶Pick1‿{Pickd⟜𝕩¨𝕨}
@@ -251,8 +252,9 @@ _onAxes_←{
 
 SelSub←{
   ! IsArray 𝕨
-  ! Nat¨ 𝕨
-  ! 𝕨 <¨ ≠𝕩
+  ! Int¨ 𝕨
+  ! ∧´⥊ 𝕨 (≥⟜-∧<) ≠𝕩
+  𝕨↩𝕨+(≠𝕩)×𝕨<0
   c←×´s←1 Cell 𝕩
   ⊑⟜(⥊𝕩)¨(c×𝕨)+⌜s⥊↕c
 }
-- 
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