From 6d1f39826963890e9612b39f92843f134b6973f3 Mon Sep 17 00:00:00 2001
From: Gregor Kleen <gkleen@yggdrasil.li>
Date: Mon, 5 Feb 2018 17:02:55 +0100
Subject: Framework for DFST edit lens

---
 edit-lens/src/Control/Edit.lhs | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

(limited to 'edit-lens/src/Control')

diff --git a/edit-lens/src/Control/Edit.lhs b/edit-lens/src/Control/Edit.lhs
index 7be8db4..19fe336 100644
--- a/edit-lens/src/Control/Edit.lhs
+++ b/edit-lens/src/Control/Edit.lhs
@@ -1,7 +1,7 @@
 \begin{comment}
 \begin{code}
 module Control.Edit
-  ( Module(..) 
+  ( Module(..), apply'
   ) where
 \end{code}
 \end{comment}
@@ -24,6 +24,8 @@ In Haskell charakterisieren wir Moduln über ihren Monoid, d.h. die Wahl des Mon
 Eine Repräsentierung als Typklasse bietet sich an:
 
 \begin{code}
+infix 5 `apply`
+
 class Monoid m => Module m where
   type Domain m :: *
   apply :: Domain m -> m -> Maybe (Domain m)
@@ -37,6 +39,10 @@ class Monoid m => Module m where
   -- ^ Calculate a representation of an element of 'Domain m' in 'Del m'
   --
   -- prop> init `apply` divInit m = m
+
+infixl 5 `apply'`
+apply' :: Module m => Maybe (Domain m) -> m -> Maybe (Domain m)
+apply' md e = flip apply e =<< md
 \end{code}
 \end{defn}
 
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