Add some helpers for Incr.

semantic-core/src/Analysis/Typecheck.hs

@@ -29,7 +29,7 @@ import qualified Data.IntSet as IntSet
 import           Data.List.NonEmpty (nonEmpty)
 import           Data.Loc
 import qualified Data.Map as Map
-import           Data.Name
+import           Data.Name hiding (subst)
 import qualified Data.Set as Set
 import           Prelude hiding (fail)
 

semantic-core/src/Data/Name.hs

@@ -14,6 +14,9 @@ module Data.Name
 , runNaming
 , NamingC(..)
 , Incr(..)
+, match
+, subst
+, incr
 ) where
 
 import           Control.Applicative
@@ -130,3 +133,13 @@ data Incr a
   = Z
   | S a
   deriving (Eq, Foldable, Functor, Ord, Show, Traversable)
+
+match :: Eq a => a -> a -> Incr a
+match x y | x == y    = Z
+          | otherwise = S y
+
+subst :: a -> Incr a -> a
+subst a = incr a id
+
+incr :: b -> (a -> b) -> Incr a -> b
+incr z s = \case { Z -> z ; S a -> s a }