I'm trying to adapt this example https://github.com/slamdata/purescript-halogen/blob/v0.12.0/examples/deep-peek/src/Main.purs#L58 (relevant part copied below), but instead of peeking the grandchild I just want to peek the child, or in this case peekList
. I also want to keep the slot type as a parameter in the peek function for peekList
.
peek :: forall a. H.ChildF ListSlot ListQueryP a -> H.ParentDSL State (ListStateP g) Query ListQueryP g ListSlot Unit
peek = coproduct peekList peekTicker <<< H.runChildF
peekList :: forall a. ListQuery a -> H.ParentDSL State (ListStateP g) Query ListQueryP g ListSlot Unit
peekList _ =
-- we're not actually interested in peeking on the list.
-- instead of defining a function like this, an alternative would be to use
-- `(const (pure unit))` in place of `peekList` in the `coproduct` function
pure unit
peekTicker :: forall a. H.ChildF TickSlot TickQuery a -> H.ParentDSL State (ListStateP g) Query ListQueryP g ListSlot Unit
peekTicker (H.ChildF _ (Tick _)) = H.modify (\st -> { count: st.count + 1 })
peekTicker _ = pure unit
How can I actually peek peekList
without losing the slot parameter?
I've tried removing the H.runChildF
:
peek = coproduct peekList (const (pure unit))
and then adding back in the slot parameter to peekList
:
peekList :: forall a. H.ChildF ListSlot ListQuery a -> H.ParentDSL State (ListStateP g) Query ListQueryP g ListSlot Unit
But then in peek
I get the error "Could not match type ChildF with type Coproduct while trying to match type ChildF ListSlot with type Coproduct (ChildF ListSlot ListQuery)"
If I just try to use peekList
instead o peek
, i get the error "Could not match type Coproduct ListQuery (ChildF TickSlot TickQuery) with type ListQuery while trying to match type ChildF ListSlot (Coproduct ListQuery (ChildF TickSlot TickQuery)) with type ChildF ListSlot ListQuery"
Any help would be really appreciated, thanks!
I looked at the types closer and saw that the second argument to peekList is a Coproduct wrapping an Either
where the Left
value is the list query that I want to peek. So just pattern match on those and add peekList
to the component's peek
parameter. Also I had to change the type signature to use ListQueryP
instead of ListQuery
.
peekList :: forall a. H.ChildF ListSlot ListQueryP a -> H.ParentDSL State (ListStateP g) Query ListQueryP g ListSlot Unit
peekList (H.ChildF _ (Coproduct queryEi)) =
case queryEi of
Left (AddTicker a) -> pure unit
_ -> pure unit