From c8e3e06b79c54f67961fdeba1504ec1cca206719 Mon Sep 17 00:00:00 2001
From: user <user@localhost.localdomain>
Date: Mon, 23 Dec 2019 11:51:02 -0800
Subject: simple link entry habits

---
 starts/meaning-vm/habit-starts/learning-parts.cpp | 25 ++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/starts/meaning-vm/habit-starts/learning-parts.cpp b/starts/meaning-vm/habit-starts/learning-parts.cpp
index b5cd56c..1b5054b 100644
--- a/starts/meaning-vm/habit-starts/learning-parts.cpp
+++ b/starts/meaning-vm/habit-starts/learning-parts.cpp
@@ -238,18 +238,37 @@ static int __init = ([]()->int{
 	ahabit(populate-link-entry, ((link-entry, le)),
 	{
 		result = le;
-		result.set("source", c);
-		result.set("type", result.vget<links_t>().first);
-		result.set("target", result.vget<links_t>().second);
+		auto & it = result.vget<links_it>();
+		if (it != result["source"].links().end()) {
+			result.set("type", it->first);
+			result.set("target", it->second);
+		} else {
+			result.unlink("type");
+			result.unlink("target");
+		}
 	});
 	ahabit(first-link-entry, ((concept, c)),
 	{
 		result = level1::alloc(level, c.links().begin());
+		result.set("source", c);
 		(populate-link-entry)(result);
 	});
 	ahabit(last-link-entry, ((concept, c)),
 	{
 		result = level1::alloc(level, --c.links().end());
+		result.set("source", c);
+		(populate-link-entry)(result);
+	});
+	ahabit(next-link-entry, ((link-entry, le)),
+	{
+		result = le;
+		++result.vget<links_it>();
+		(populate-link-entry)(result);
+	});
+	ahabit(previous-link-entry, ((link-entry, le)),
+	{
+		result = le;
+		--result.vget<links_it>();
 		(populate-link-entry)(result);
 	});
 
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