From f1da89b4cb5afd413aae8cd61fa31b3d45dcd18b Mon Sep 17 00:00:00 2001
From: Thomas Guillermo Albers Raviola <thomas@thomaslabs.org>
Date: Tue, 28 Jul 2026 19:55:39 +0200
Subject: Simplify contr

---
 tensors.mac | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/tensors.mac b/tensors.mac
index 6d7248a..e8e5a4f 100644
--- a/tensors.mac
+++ b/tensors.mac
@@ -3,19 +3,15 @@
 /* NOTE: buildq works like splicing a list with quasiquote in lisp; escaped
 items are defined at start of quote */
 contr(expr, var) ::= (
-  if listp(var) and length(var) > 1 then
-  block([head, tail],
-    head : first(var),
-    tail : rest(var),
-    buildq([expr, head, tail], sum(contr(expr, tail), head, 1, 4)))
-  elseif listp(var) and length(var) = 1 then
-  block([head],
-    head : first(var),
-    buildq([expr, head], sum(expr, head, 1, 4)))
-  elseif listp(var) then
-  expr
-  else
-  buildq([expr, var], sum(expr, var, 1, 4)))$
+  if listp(var) and length(var) > 1 then buildq(
+    [expr, head : first(var), tail : rest(var)],
+    sum(contr(expr, tail), head, 1, 4))
+  elseif listp(var) and length(var) = 1 then buildq(
+    [expr, head : first(var)], sum(expr, head, 1, 4))
+  elseif listp(var) then (
+    expr)
+  else buildq([expr, var],
+    sum(expr, var, 1, 4)));
 
 /* Differentiate with respect to nth coordinate */
 cdiff(func, coord) := diff(func, ct_coords[coord])$
-- 
cgit v1.3