&& intrusive boolean casting memo

[mizulu]

https://playground.solidjs.com/anonymous/bfbaa513-3926-4e33-a20e-eb4335544957

<>{count() && Date.now()}</>

compiles to

_$memo(() => _$memo(() => !!count())() && Date.now())

any thoughts, I understand this is some sort of optimization
to memo the condition, but what is the reason that it also explicitly cast to boolean?

this breaks expectations from the evaluation of binary logical operators

and to escape this we need something like this

  <>{count() && (count() && Date.now())}</>

_$memo(() => !!count())() && count() && Date.now()

https://playground.solidjs.com/anonymous/54871ab2-874e-4b70-8c5c-2504e30718f9

[mizulu]

ok so the reason this optimization exists is to handle the following

{ posts() && <Posts/>}

this is equivalent to using

<Show when={posts()}><Posts/></Show>

The intention is to show the posts if we have any posts
we don't want the component to re render when posts() mutates ( for example new posts are added, it should be handled by the fine grain reactivity here after )

casting to Boolean and memoizing solve for not re-rendering on any truthy value change.

In <Show keyed> we can use keyed to trigger a re render on any truthy value change
but in the javascript expression there is no way to escape that compiler optimization

so instead we need to revert to

<Show when={count()} keyed>
        {Date.now()}
</Show>

or even

  <>{()=>count() && Date.now()}</>

which is not recommended and might raise a warning in the types.

https://playground.solidjs.com/anonymous/d926ace1-75ba-4cc3-945f-bcf5e6578cdb

There is no equivalent to the @once to help us escape the memo

{ /*@!memo*/ count() && Date.now() } 

like we have the
https://docs.solidjs.com/reference/jsx-attributes/once

thanks @ryansolid for the feedback in the discord