Fixing ordering to lexicographical

Thanks to @zoep for the idea!

Author: msooseth

src/EVM/Types.hs

@@ -490,16 +490,16 @@ instance Ord Prop where
   PBool a <= PBool b = a <= b
   PEq (a :: Expr x) (b :: Expr x) <= PEq (c :: Expr y) (d :: Expr y)
     = case eqT @x @y of
-       Just Refl ->        a < c || b < d || (a == c && b == d)
+       Just Refl ->        a <= c || (a == c && b <= d)
        Nothing -> toNum a <= toNum c
-  PLT a b  <= PLT c d    = a < c || b < d || (a == c && b == d)
-  PGT a b  <= PGT c d    = a < c || b < d || (a == c && b == d)
-  PGEq a b <= PGEq c d   = a < c || b < d || (a == c && b == d)
-  PLEq a b <= PLEq c d   = a < c || b < d || (a == c && b == d)
   PNeg a   <= PNeg b     = a <= b
-  PAnd a b <= PAnd c d   = a < c || b < d || (a == c && b == d)
-  POr a b  <= POr c d    = a < c || b < d || (a == c && b == d)
-  PImpl a b <= PImpl c d = a < c || b < d || (a == c && b == d)
+  PLT a b  <= PLT c d    = a <= c || (a == c && b <= d)
+  PGT a b  <= PGT c d    = a <= c || (a == c && b <= d)
+  PGEq a b <= PGEq c d   = a <= c || (a == c && b <= d)
+  PLEq a b <= PLEq c d   = a <= c || (a == c && b <= d)
+  PAnd a b <= PAnd c d   = a <= c || (a == c && b <= d)
+  POr a b  <= POr c d    = a <= c || (a == c && b <= d)
+  PImpl a b <= PImpl c d = a <= c || (a == c && b <= d)
   a <= b = asNum a <= asNum b
     where
       asNum :: Prop -> Int