From 9291f9a0bb5eee851ebd7ee79f6f4cb70b5e49e2 Mon Sep 17 00:00:00 2001
From: Ashok Kimmel <59121897+ashokkimmel@users.noreply.github.com>
Date: Tue, 28 Oct 2025 14:58:37 -0500
Subject: [PATCH] Add Elem type family and ElemSym data type

Note, I did not test this.
---
 src/Symparsec/Parser/While/Predicates.hs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/Symparsec/Parser/While/Predicates.hs b/src/Symparsec/Parser/While/Predicates.hs
index 9c8336c..16ab9bd 100644
--- a/src/Symparsec/Parser/While/Predicates.hs
+++ b/src/Symparsec/Parser/While/Predicates.hs
@@ -116,3 +116,11 @@ type family IsDecDigit ch where
 type IsDecDigitSym :: Char ~> Bool
 data IsDecDigitSym ch
 type instance App IsDecDigitSym ch = IsDecDigit ch
+
+type Elem :: [a] -> a -> Bool 
+type family Elem where 
+  Elem (_:xs) x = Elem xs x
+  Elem '[] _ = 'False
+  Elem (x':_) x = 'True
+data ElemSym lst ch
+type instance (App (ElemSym lst)) a = Elem lst a