Rework the constructors and eliminators a bit to not use tagged.

semantic-diff.cabal

@@ -61,7 +61,6 @@ library
                      , QuickCheck >= 2.8.1
                      , quickcheck-text
                      , semigroups
-                     , tagged
                      , text >= 1.2.1.3
                      , text-icu
                      , these

src/Data/Record.hs

@@ -1,7 +1,6 @@
 {-# LANGUAGE DataKinds, FlexibleContexts, GADTs, GeneralizedNewtypeDeriving, KindSignatures, MultiParamTypeClasses, TypeOperators #-}
 module Data.Record where
 
-import Data.Tagged
 import Prologue
 
 -- | A type-safe, extensible record structure.
@@ -21,16 +20,13 @@ infixr 0 .:.
 infix 9 :=>
 
 -- | A phantom type tag constructor.
-newtype a :=> b = (:=>) (Tagged a b)
+newtype a :=> b = Field { unField :: b }
 
 -- | Smart constructor for type-tagged data fields.
 -- |
 -- | This has type a :=> b. When you require a to be some concrete type (and you usually will), it should be provided by context, whether using ascription, a type signature for the binding, `asTypeOf`, or some other way to allow the specific type to be inferred.
 field :: b -> a :=> b
-field = (:=>) . Tagged
-
-unField :: a :=> b -> b
-unField ((:=>) b) = unTagged b
+field = Field
 
 
 -- Classes