Add concludedP as analogue to conclude from semigroupoids

tomjaguarpaw · Apr 10, 2023 · 6b03c15 · 6b03c15
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -15,6 +15,7 @@
   - Class methods now capture two perspectives: "`Decidable`
     operations on the input (`decideP`)" and "eithering" (`(+++!)`).
 * Add `decidedP = decideP id`
+* Add `concludedP = concludeP id`
 
 # 0.11.0.3
 

diff --git a/Data/Profunctor/Product/Class.hs b/Data/Profunctor/Product/Class.hs
@@ -219,3 +219,10 @@ class SemisumProfunctor p => SumProfunctor p where
   concludeP :: (a -> Void) -> p a x
   concludeP f = Profunctor.dimap f absurd voidP
   {-# MINIMAL voidP | concludeP #-}
+
+-- | Analogue to @concluded@ (from "semigroupoids") or
+-- 'Data.Functor.Contravariant.Divisible.lost'. Potentially more
+-- meaningful than 'concludeP', as it shows that we definitely cannot
+-- receive _anything_ on the input side.
+concludedP :: SumProfunctor p => p Void x
+concludedP = concludeP id