From ad1de17e64d1515d04adcfd6f0d762368397ee8a Mon Sep 17 00:00:00 2001 From: Rob Rix Date: Tue, 8 Oct 2019 15:08:17 -0400 Subject: [PATCH] :memo: Element. --- semantic-tags/src/AST/Element.hs | 1 + 1 file changed, 1 insertion(+) diff --git a/semantic-tags/src/AST/Element.hs b/semantic-tags/src/AST/Element.hs index a0a34e84e..fb691e1e5 100644 --- a/semantic-tags/src/AST/Element.hs +++ b/semantic-tags/src/AST/Element.hs @@ -6,6 +6,7 @@ module AST.Element import GHC.Generics import GHC.TypeLits (ErrorMessage(..), TypeError) +-- | Projection of an element out of a tree of sums, particularly suitable for use with highly branching (e.g. balanced) trees. class Element sub sup where prj :: sup a -> Maybe (sub a)