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Add "nullIsNothing" #36

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Add "nullIsNothing" #36

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ffee179
Add "nullIsNothing"
PaulJohnson Aug 25, 2021
97affa0
Corrected example in Haddock comment.
PaulJohnson Aug 25, 2021
054cfbd
Added nullIsDefault as well.
PaulJohnson Aug 26, 2021
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Added nullIsDefault as well.
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@PaulJohnson
PaulJohnson committed Aug 26, 2021
commit 054cfbd0c87163d24903a05d764519f0b4a5478c
19 changes: 19 additions & 0 deletions src/Data/Aeson/Lens.hs
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Expand Up @@ -30,6 +30,7 @@ module Data.Aeson.Lens
, _Integral
, nonNull
, nullIsNothing
, nullIsDefault
-- * Primitive
, Primitive(..)
, AsPrimitive(..)
Expand Down Expand Up @@ -304,6 +305,24 @@ nullIsNothing p = withPrism p $ \bk fw ->
in prism bk1 fw1


-- | Treat a 'Null' value as a default
--
-- >>> Number 123 ^? nullIsDefault 0 _Integer
-- Just 123
--
-- >>> Null ^? nullIsDefault 0 _Integer
-- Just 0
--
-- >>> "xyz" ^? nullIsDefault 0 _Integer
-- Nothing
nullIsDefault :: q -> Prism' Value q -> Prism' Value q
nullIsDefault q p = withPrism p $ \bk fw ->
let
fw1 Null = Right q
fw1 x = fw x
in prism bk fw1


------------------------------------------------------------------------------
-- Non-primitive traversals
------------------------------------------------------------------------------
Expand Down