From 1adad63b14aa8d13295fb0d68fbdc8ab988775b2 Mon Sep 17 00:00:00 2001
From: Tom Smeding <tom@tomsmeding.com>
Date: Thu, 23 Oct 2025 23:43:54 +0200
Subject: Add uniform-tree test and benchmark

We need an optimisation that detects replicate-like behaviour and turns
it into actual replicates, which should then be fused away. The problem
is exhibited by this function exUniformFree.
---
 src/Example.hs | 11 +++++++++++
 1 file changed, 11 insertions(+)

(limited to 'src/Example.hs')

diff --git a/src/Example.hs b/src/Example.hs
index 1784a48..bccc8de 100644
--- a/src/Example.hs
+++ b/src/Example.hs
@@ -167,3 +167,14 @@ neuralGo =
       (Value dinput_2 `SCons` Value dlay3_2 `SCons` Value dlay2_2 `SCons` Value dlay1_2 `SCons` SNil) = drevByFwdInterp knownEnv neural argument 1.0
   in trace (ppExpr knownEnv revderiv) $
      (primal, (dlay1_1, dlay2_1, dlay3_1, dinput_1), (dlay1_2, dlay2_2, dlay3_2, dinput_2))
+
+-- The build body uses free variables in a non-linear way, so their primal
+-- values are required in the dual of the build. Thus, compositionally, they
+-- are stored in the tape from each individual lambda invocation. This results
+-- in n copies of y and z, where only one copy would have sufficed.
+exUniformFree :: Ex '[R, I64] R
+exUniformFree = fromNamed $ lambda #n $ lambda #x $ body $
+  let_ #y (#x * 2) $
+  let_ #z (#x * 3) $
+    idx0 $ sum1i $
+      build1 #n $ #i :-> #y * #z + toFloat_ #i
-- 
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