Define a gensym operation, producing fresh names.

Co-Authored-By: Patrick Thomson <patrick.william.thomson@gmail.com>

src/Data/Abstract/Name.hs

@@ -2,11 +2,14 @@
 module Data.Abstract.Name
 ( Name
 -- * Constructors
+, gensym
 , name
 , nameI
 , formatName
 ) where
 
+import           Control.Monad.Effect
+import           Control.Monad.Effect.Fresh
 import           Data.Aeson
 import qualified Data.Char as Char
 import           Data.Text (Text)
@@ -33,6 +36,9 @@ instance Primitive Name where
   decodePrimitive = Name . LT.toStrict <$> Decode.text <|> I <$> Decode.int
   primType _ = Bytes
 
+gensym :: (Functor (m effs), Member Fresh effs, Effectful m) => m effs Name
+gensym = I <$> fresh
+
 -- | Construct a 'Name' from a 'Text'.
 name :: Text -> Name
 name = Name