Define a generic handler for the Unit effect.

Co-Authored-By: Ayman Nadeem <aymannadeem@gmail.com>

src/Control/Abstract/Value.hs

@@ -25,6 +25,7 @@ module Control.Abstract.Value
 , runWhile
 , WhileC(..)
 , Unit(..)
+, runUnit
 , UnitC(..)
 ) where
 
@@ -201,6 +202,11 @@ instance Effect (Unit value) where
 
 newtype UnitC value m a = UnitC { runUnitC :: m a }
 
+runUnit :: Carrier (Unit value :+: sig) (UnitC value (Eff m))
+        => Evaluator term address value (UnitC value (Eff m)) a
+        -> Evaluator term address value m a
+runUnit = raiseHandler $ runUnitC . interpret
+
 class Show value => AbstractIntro value where
   -- | Construct an abstract unit value.
   --   TODO: This might be the same as the empty tuple for some value types