Robert Vollmert wrote:
In short, I'm constantly running into what appear to be artificial type
restrictions in Control.Arrow.ArrowTree. For example, the signature of
"deep" is
deep :: (Tree t, ArrowTree a) => a (t b) (t b) -> a (t b) (t b)
instead of the more general
deep :: (Tree t, ArrowTree a) => a (t b) c -> a (t b) c
You are right, there is no harm generalizing deep, since a related
combinator, multi, has the more general type. Meanwhile, I don't think
deep (hasName "a") >>> getLink
looks too bad. :)
Under suitable assumptions, you can use
multi getLink
if you want.
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