From 390a8732eff8c3e93a6927212d5fe234f865ca99 Mon Sep 17 00:00:00 2001
From: Pierre Thierry <pierre@nothos.net>
Date: Wed, 8 Apr 2026 15:36:48 +0200
Subject: [PATCH] Add runNonDetFinal [WIP]

WARNING: this doesn't build
---
 src/Polysemy/NonDet.hs | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/src/Polysemy/NonDet.hs b/src/Polysemy/NonDet.hs
index 419ba3d3..784dc966 100644
--- a/src/Polysemy/NonDet.hs
+++ b/src/Polysemy/NonDet.hs
@@ -1,5 +1,9 @@
+{-# LANGUAGE AllowAmbiguousTypes #-}
 {-# LANGUAGE DeriveAnyClass  #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE UndecidableInstances #-}
 
 -- | Description: Interpreters for 'NonDet'
 module Polysemy.NonDet
@@ -18,6 +22,7 @@ import Data.Maybe
 
 import Polysemy
 import Polysemy.Error
+import Polysemy.Final (Final, interpretFinal, liftS, runS)
 import Polysemy.Internal
 import Polysemy.Internal.NonDet
 import Polysemy.Internal.Union
@@ -72,6 +77,18 @@ nonDetToError (e :: e) = interpretH $ \case
 {-# INLINE nonDetToError #-}
 
 
+------------------------------------------------------------------------------
+-- | Run a 'NonDet' effect in terms of the 'Final' 'Alternative' @m@.
+runNonDetFinal :: (Member (Final m) r, Alternative m) => Sem (NonDet ': r) a -> Sem r a
+runNonDetFinal = interpretFinal $ \case
+  Empty -> liftS empty
+  Choose semA semB -> do
+    a <- runS semA
+    b <- runS semB
+    pure $ a <|> b
+{-# INLINE runNonDetFinal #-}
+
+
 --------------------------------------------------------------------------------
 -- This stuff is lifted from 'fused-effects'. Thanks guys!
 runNonDetC :: (Alternative f, Applicative m) => NonDetC m a -> m (f a)