From 3fd6bd2f7be0b6592929e6827c1351c2f9b06a1a Mon Sep 17 00:00:00 2001 From: Jason Shipman Date: Wed, 24 May 2023 18:04:57 -0400 Subject: [PATCH] Add useSteppingAff hook --- src/React/Basic/Hooks/Aff.purs | 27 +++++++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-) diff --git a/src/React/Basic/Hooks/Aff.purs b/src/React/Basic/Hooks/Aff.purs index 45e0bed..b05d404 100644 --- a/src/React/Basic/Hooks/Aff.purs +++ b/src/React/Basic/Hooks/Aff.purs @@ -1,5 +1,6 @@ module React.Basic.Hooks.Aff ( useAff + , useSteppingAff , UseAff(..) , useAffReducer , AffReducer @@ -37,11 +38,33 @@ useAff :: deps -> Aff a -> Hook (UseAff deps a) (Maybe a) -useAff deps aff = +useAff = useAff' (const Nothing) + +--| A variant of `useAff` where the asynchronous effect's result is preserved up +--| until the next run of the asynchronous effect _completes_. +--| +--| Contrast this with `useAff`, where the asynchronous effect's result is +--| preserved only up until the next run of the asynchronous effect _starts_. +useSteppingAff :: + forall deps a. + Eq deps => + deps -> + Aff a -> + Hook (UseAff deps a) (Maybe a) +useSteppingAff = useAff' identity + +useAff' :: + forall deps a. + Eq deps => + (Maybe (Either Error a) -> Maybe (Either Error a)) -> + deps -> + Aff a -> + Hook (UseAff deps a) (Maybe a) +useAff' initUpdater deps aff = coerceHook React.do result /\ setResult <- useState Nothing useEffect deps do - setResult (const Nothing) + setResult initUpdater fiber <- launchAff do r <- try aff pFad - Phonifier reborn

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