From 906ae5ad3a960e4c7d7c32528ced79ba63ee2238 Mon Sep 17 00:00:00 2001
From: Justin Bedo <cu@cua0.org>
Date: Fri, 27 Jan 2023 18:08:42 +1100
Subject: add beta' distribution

---
 src/PPL/Distr.hs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/PPL/Distr.hs b/src/PPL/Distr.hs
index 797379b..093e102 100644
--- a/src/PPL/Distr.hs
+++ b/src/PPL/Distr.hs
@@ -69,6 +69,10 @@ beta a b = do
   y <- gamma b
   pure $ x / (x + y)
 
+beta' a b = do
+  p <- beta a b
+  pure $ p / (1-p)
+
 bern p = (< p) <$> uniform
 
 binom n = fmap (length . filter id . take n) . iid . bern
-- 
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