From 6dcfff4716c4555c8eaccb4cb9acc1f3040997ad Mon Sep 17 00:00:00 2001
From: Rob Rix <rob.rix@me.com>
Date: Thu, 23 Feb 2017 11:03:25 -0500
Subject: [PATCH] Loosen the Eq constraint in RWS to an Eq1 constraint.

---
 src/Data/RandomWalkSimilarity.hs | 6 ++++--
 src/Interpreter.hs               | 5 +++--
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/Data/RandomWalkSimilarity.hs b/src/Data/RandomWalkSimilarity.hs
index d5c93340a..2e97dc681 100644
--- a/src/Data/RandomWalkSimilarity.hs
+++ b/src/Data/RandomWalkSimilarity.hs
@@ -21,6 +21,8 @@ import Control.Monad.Random
 import Control.Monad.State
 import Data.Align.Generic
 import Data.Array
+import Data.Functor.Classes
+import Data.Functor.Classes.Eq.Generic
 import Data.Functor.Listable
 import Data.Hashable
 import qualified Data.IntMap as IntMap
@@ -46,7 +48,7 @@ type DiffTerms f fields = Term f (Record fields) -> Term f (Record fields) -> Ma
 --
 -- This implementation is based on the paper [_RWS-Diff—Flexible and Efficient Change Detection in Hierarchical Data_](https://github.com/github/semantic-diff/files/325837/RWS-Diff.Flexible.and.Efficient.Change.Detection.in.Hierarchical.Data.pdf).
 rws :: forall f fields.
-       (GAlign f, Traversable f, Eq (f (Term f Category)), HasField fields Category, HasField fields (Maybe FeatureVector))
+       (GAlign f, Traversable f, Eq1 f, HasField fields Category, HasField fields (Maybe FeatureVector))
     => DiffTerms f fields -- ^ A function which compares a pair of terms recursively, returning 'Just' their diffed value if appropriate, or 'Nothing' if they should not be compared.
     -> [Term f (Record fields)] -- ^ The list of old terms.
     -> [Term f (Record fields)] -- ^ The list of new terms.
@@ -149,7 +151,7 @@ rws compare as bs
     -- Possibly replace terms in a diff.
     replaceIfEqual :: Term f (Record fields) -> Term f (Record fields) -> Maybe (Diff f (Record fields))
     replaceIfEqual a b
-      | (category <$> a) == (category <$> b) = hylo wrap runCofree <$> zipTerms (eraseFeatureVector a) (eraseFeatureVector b)
+      | gliftEq (==) (category <$> a) (category <$> b) = hylo wrap runCofree <$> zipTerms (eraseFeatureVector a) (eraseFeatureVector b)
       | otherwise = Nothing
 
     cost = iter (const 0) . (1 <$)
diff --git a/src/Interpreter.hs b/src/Interpreter.hs
index 88d40711c..50732a868 100644
--- a/src/Interpreter.hs
+++ b/src/Interpreter.hs
@@ -3,8 +3,9 @@ module Interpreter (diffTerms) where
 
 import Algorithm
 import Data.Align.Generic
-import Data.Functor.Foldable
 import Data.Functor.Both
+import Data.Functor.Classes
+import Data.Functor.Foldable
 import Data.RandomWalkSimilarity as RWS
 import Data.Record
 import Data.These
@@ -86,7 +87,7 @@ algorithmWithTerms t1 t2 = maybe (linearly t1 t2) (fmap annotate) $ case (unwrap
       (Nothing, Nothing) -> Nothing
 
 -- | Run an algorithm, given functions characterizing the evaluation.
-runAlgorithm :: (GAlign f, HasField fields Category, Eq (f (Cofree f Category)), Traversable f, HasField fields (Maybe FeatureVector))
+runAlgorithm :: (Eq1 f, GAlign f, Traversable f, HasField fields Category, HasField fields (Maybe FeatureVector))
   => (Cofree f (Record fields) -> Cofree f (Record fields) -> Maybe (Free (CofreeF f (Both (Record fields))) (Patch (Cofree f (Record fields))))) -- ^ A function to diff two subterms recursively, if they are comparable, or else return 'Nothing'.
   -> Algorithm (Cofree f (Record fields)) (Free (CofreeF f (Both (Record fields))) (Patch (Cofree f (Record fields)))) a -- ^ The algorithm to run.
   -> a