Lower precedence of equality constraints

This drops them to the new precedence pREC_CTX, which makes single
eqaulity constraints show up as (a ~ b) => ty, in line with GHC's
rendering. Additional tests added to make sure other type operators
render as intended. Current behavior matches GHC

1 files changed, 16 insertions, 9 deletions

diff --git a/html-test/src/TypeOperators.hs b/html-test/src/TypeOperators.hs
index edbb9344..e69e89cb 100644
--- a/html-test/src/TypeOperators.hs
+++ b/html-test/src/TypeOperators.hs
@@ -1,12 +1,5 @@
-{-# LANGUAGE TypeOperators #-}
-module TypeOperators (
-  -- * stuff
-  (:-:),
-  (:+:),
-  Op,
-  O(..),
-  biO,
-) where
+{-# LANGUAGE TypeOperators, GADTs, MultiParamTypeClasses, FlexibleContexts #-}
+module TypeOperators where
 
 data a :-: b
 
@@ -16,5 +9,19 @@ data a `Op` b
 
 newtype (g `O` f) a = O { unO :: g (f a) }
 
+class a <=> b
+
 biO :: (g `O` f) a
 biO = undefined
+
+f :: (a ~ b) => a -> b
+f = id
+
+g :: (a ~ b, b ~ c) => a -> c
+g = id
+
+x :: ((a :-: a) <=> (a `Op` a)) => a
+x = undefined
+
+y :: (a <=> a, (a `Op` a) <=> a) => a
+y = undefined