From 190a4dc5f5398e6646823aa41637f54cc8cb54aa Mon Sep 17 00:00:00 2001
From: Justin Bedo <cu@cua0.org>
Date: Fri, 20 Jan 2023 09:17:05 +1100
Subject: add symmetry

---
 src/PPL/Sampling.hs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

(limited to 'src/PPL/Sampling.hs')

diff --git a/src/PPL/Sampling.hs b/src/PPL/Sampling.hs
index 1d20838..b3b8a90 100644
--- a/src/PPL/Sampling.hs
+++ b/src/PPL/Sampling.hs
@@ -25,8 +25,8 @@ importance n m = do
     cumsum = tail . scanl (+) 0
     accumulate = uncurry zip . second cumsum . unzip
 
-mh :: MonadIO m => Double -> Meas a -> m [(a, Log Double)]
-mh p m = do
+mh :: MonadIO m => Double -> Double -> Meas a -> m [(a, Log Double)]
+mh p q m = do
   newStdGen
   g <- getStdGen
   let (g1, g2) = split g
@@ -37,7 +37,7 @@ mh p m = do
     step (t, x, w) = do
       g <- get
       let (g1, g2) = split g
-          t' = mutateTree p g1 t
+          t' = mutateTree p q g1 t
           (x', w') = head $ samples m t'
           ratio = w' / w
           (Exp . log -> r, g3) = random g2
-- 
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