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tonymorris/blah.hs

Created October 22, 2019 09:33
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blah.hs
nonEmptyIso ::
Iso [a] [b] (Maybe (NonEmpty a)) (Maybe (NonEmpty b))
nonEmptyIso =
iso
(
\case
[] ->
Nothing
h:t ->
Just (h:|t)
)
(
\case
Nothing ->
[]
Just (h:|t) ->
h:t
)
blah ::
[Maybe a]
-> Maybe (NonEmpty a)
blah =
view nonEmptyIso . catMaybes
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