From 2bd69bf893b7e1ebe4186639526451caf2083b12 Mon Sep 17 00:00:00 2001
From: Greg Brown <greg.brown01@ed.ac.uk>
Date: Fri, 2 Dec 2022 14:14:44 +0000
Subject: WIP: Frex is free

---
 src/Data/Setoid/Indexed.idr | 7 +++++++
 1 file changed, 7 insertions(+)

(limited to 'src/Data/Setoid/Indexed.idr')

diff --git a/src/Data/Setoid/Indexed.idr b/src/Data/Setoid/Indexed.idr
index 7277932..db5fb07 100644
--- a/src/Data/Setoid/Indexed.idr
+++ b/src/Data/Setoid/Indexed.idr
@@ -39,6 +39,13 @@ public export
 (.index) : ISetoid a -> a -> Setoid
 (.index) x i = MkSetoid (x.U i) (x.relation i) (x.equivalence i)
 
+public export
+(.reindex) : ISetoid b -> (f : a -> b) -> ISetoid a
+(.reindex) x f = MkISetoid
+  (\i => x.U $ f i)
+  (\i => x.relation $ f i)
+  (\i => x.equivalence $ f i)
+
 public export
 isetoid : (a -> Type) -> ISetoid a
 isetoid u = MkISetoid u (\_ => Equal) (\_ => equiv)
-- 
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