From 2a15ddf776ba421e1fb1d3bc31eaee8a39fa1917 Mon Sep 17 00:00:00 2001 From: Gregor Kleen Date: Mon, 6 Jun 2016 02:48:33 +0200 Subject: No context is admissable --- src/Sequence/Formula.hs | 3 +++ 1 file changed, 3 insertions(+) diff --git a/src/Sequence/Formula.hs b/src/Sequence/Formula.hs index 9000c58..d486bab 100644 --- a/src/Sequence/Formula.hs +++ b/src/Sequence/Formula.hs @@ -46,6 +46,9 @@ instance a :<: (a, b) where instance a :<: (b, a) where ctx' = _2 +instance () :<: a where + ctx' = united + data Context small = forall large. (small :<: large) => Context large ctx :: Traversal' (Context input) input -- cgit v1.2.3