Add Cron module and Schedule.cron constructor

[fubhy]

• Add cron expression parser
• Add cron match calculator
• Add cron next calculator
• Add Schedule.cron constructor
• Write tests for Schedule.cron

Fixes #1524

[changeset-bot]

🦋 Changeset detected

Latest commit: 1c8ebbf

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 16 packages

Name	Type
effect	Minor
@effect/cli	Major
@effect/opentelemetry	Major
@effect/platform-browser	Major
@effect/platform-bun	Major
@effect/platform-node	Major
@effect/platform	Major
@effect/printer-ansi	Major
@effect/printer	Major
@effect/rpc-http-node	Major
@effect/rpc-http	Major
@effect/rpc-nextjs	Major
@effect/rpc-workers	Major
@effect/rpc	Major
@effect/schema	Major
@effect/typeclass	Major

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[fubhy]

This is an optimization that makes this work with composed schedules without the overhead of re-calculating the next Cron interval repeatedly (e.g. when composing this with sth. like Schedule.fixed at second intervals "run every second on the first minute of the second hour of each monday between january and march" :-P)

[mikearnaldi]

Is there any usage expectation of Cron apart from Schedule? if not it could be an internal module

[fubhy]

Is there any usage expectation of Cron apart from Schedule? if not it could be an internal module

Would that be your preference? I don't have a strong preference either way. I can /see/ this being useful outside of Schedule in user land but I don't have an immediate use-case myself so would be happy either way.

There are several cron npm packages with a few million weekly downloads:

• https://www.npmjs.com/package/cron
• https://www.npmjs.com/package/croner
• https://www.npmjs.com/package/node-cron

Hard to say for what these are mostly used.

I don't see much harm in maintaining this as a public module other than the maintenance burden. Your call ;-)

[mikearnaldi]

Is there any usage expectation of Cron apart from Schedule? if not it could be an internal module

Would that be your preference? I don't have a strong preference either way. I can /see/ this being useful outside of Schedule in user land but I don't have an immediate use-case myself so would be happy either way.

There are several cron npm packages with a few million weekly downloads:

• https://www.npmjs.com/package/cron
• https://www.npmjs.com/package/croner
• https://www.npmjs.com/package/node-cron

Hard to say for what these are mostly used.

I don't see much harm in maintaining this as a public module other than the maintenance burden. Your call ;-)

My question was more out of curiosity, I agree regarding the maintenance burden, if this is stable it can be publicly exposed, only downside is if this is not stable and leads to breaking changes. I don't have a strong opinion, we can start having it public for now and reserve the right to decide otherwise if we feel like.