15 Aug
2013
15 Aug
'13
7:37 p.m.
+1. I also blogged about it before:
http://ro-che.info/articles/2013-03-11-generalizing-gfoldl.html
http://ro-che.info/articles/2013-03-29-gtraverse-vs-gfoldl.html
* Edward Kmett
Data.Data provides an gmapM as an analogue to mapM but not one to traverse.
The following definition from lens fills in this gap, but it probably belongs in Data.Data alongside its kin.
gtraverse :: (Applicative f, Data a) => (forall d. Data d => d -> f d) -> a -> f a
gtraverse f = gfoldl (\x y -> x <*> f y) pure
Discussion period: 2 weeks
-Edward Kmett
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