channels: custom hooks

[arthyn]

PR Checklist

• Includes changes to desk files
• Describes how you tested the PR locally (test ship vs livenet)
• If a new feature, includes automated tests
• Comments added anywhere logic may be confusing without context

[Fang-]

Partial comments. We should continue at some point (from $result and onward).

[Fang-]

Suggested change

	+$ action
	$% [%add name=@t src=@t cron=(unit @dr)]
	+$ action
	$: =nest:c
	$% [%add name=@t src=@t cron=(unit @dr)]
	...
	== ==

[Fang-]

As written this is per-channel (many-to-one), but could be worth doing many-to-many, so you don't have the experience of needing to "copy" hooks into other channels, but rather just enabling them for the other channels.

Something like this:

Suggested change

	:: $hooks: collection of hooks, the order they should be run in, and
	:: any delayed hooks that need to be run
	++ hooks
	$: hooks=(map id hook)
	order=(rev (list id))
	delayed=(map id delayed-hook)
	==
	:: $hooks: collection of hooks, the order they should be run in, and
	:: any delayed hooks that need to be run
	++ hooks
	$: hooks=(map id hook)
	order=(map nest:c (list id))
	delayed=(map id [for=nest:c delayed-hook])
	==

And then probably pull .enabled out of $hook and just make that implicit in hooks being present in the .order for any given $nest.

This also gives you the benefit of being able to do "global" state in a hook. If the hook cares about only operating in the local context, it just keeps a (map nest:c hook-state) instead. (So tbc, state.hook would remain just a $vase.)

[Fang-]

We probably want a "written for" version tag alongside the source code, so that we can do backcompat for all the trivial cases (and possibly for everything).

[Fang-]

Suggested change

	+$ event
	$% [%on-post on-post]
	[%on-reply on-reply]
	[%cron ~]
	[%delay delayed-hook]
	==
	+$ event
	$% [%on-post on-post]
	[%on-reply on-reply]
	[%cron ~]
	[%wake delayed-hook]
	==

Maybe %wake here, and then %wait for the $effect below.