Make Language a type synonym

Author: alt-romes

TODO

@@ -1,3 +1,4 @@
+[ ] Newtype over ClassId and abstract implementation. Only way to get ClassIds is through representation and adding
 [ ] Freeze/Unfreeze implementation of Union Find with unboxed vectors
 [ ] Point out module should be imported qualified, and rename emptyEG to just `empty`
 [ ] Point out that we have pure functional e-graphs!!

src/Data/Equality/Language.hs

@@ -1,4 +1,5 @@
 {-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE ConstraintKinds #-}
 {-|
 
 Defines 'Language', which is the required constraint on /expressions/ that are
@@ -38,5 +39,5 @@ import Data.Functor.Classes
 -- e-graphs), note that it must satisfy the other class constraints. In
 -- particular an 'Data.Equality.Analysis.Analysis' must be defined for the
 -- language.
-class (Traversable l, Ord1 l) => Language l where
+type Language l = (Traversable l, Ord1 l)
 

test/Invariants.hs

@@ -37,7 +37,7 @@ import Sym
 -- TODO: Use type level symbol to define the analysis
 type role SimpleExpr nominal
 newtype SimpleExpr l = SE (Expr l)
-    deriving (Functor, Foldable, Traversable, Show1, Eq1, Ord1, Language)
+    deriving (Functor, Foldable, Traversable, Show1, Eq1, Ord1)
 
 -- | When a rewrite of type "x":=c where x is a pattern variable and c is a
 -- constant is used in equality saturation of any expression, all e-classes

test/Lambda.hs

@@ -112,9 +112,6 @@ instance Analysis FreeVars Lambda where
 
   joinA = (<>)
 
-
-instance Language Lambda
-
 instance Num (Fix Lambda) where
     fromInteger = Fix . Num . fromInteger
     (+) a b = Fix $ Add a b

test/SimpleSym.hs

@@ -17,7 +17,6 @@ import Text.Show.Deriving
 import Data.Equality.Utils
 import Data.Equality.Matching
 import Data.Equality.Saturation
-import Data.Equality.Language
 import Data.Equality.Analysis
 import Data.Equality.Graph.Lens ((^.), _data)
 
@@ -34,8 +33,6 @@ deriveEq1   ''SymExpr
 deriveOrd1  ''SymExpr
 deriveShow1 ''SymExpr
 
-instance Language SymExpr
-
 instance Analysis (Maybe Double) SymExpr where
   makeA = \case
     Const x -> Just x

test/Sym.hs

@@ -60,8 +60,6 @@ deriveEq1 ''Expr
 deriveOrd1 ''Expr
 deriveShow1 ''Expr
 
-instance Language Expr
-
 instance IsString (Fix Expr) where
     fromString = Fix . Sym
 

test/T1.hs

@@ -100,8 +100,6 @@ instance Floating (Pattern TreeF) where
   l ** r      = undefined
   logBase l r = undefined
 
-instance Language TreeF
-
 cost :: CostFunction TreeF Int
 cost = \case
   ConstF _ -> 5

test/T2.hs

@@ -11,7 +11,6 @@ import Prelude hiding (not)
 import Test.Tasty.HUnit
 import Data.Deriving
 import Data.Equality.Matching
-import Data.Equality.Language
 import Data.Equality.Extraction
 import Data.Equality.Saturation
 
@@ -26,8 +25,6 @@ deriveEq1 ''Lang
 deriveOrd1 ''Lang
 deriveShow1 ''Lang
 
-instance Language Lang
-
 x, y :: Pattern Lang
 x = "x"
 y = "y"