Daily Thought - 2024-12-22
Hey, I'm Hanno! These are my daily thoughts on Crosscut, the programming language I'm creating. If you have any questions, comments, or feedback, please get in touch!
This thought was published before Crosscut was called Crosscut! If it refers to "Caterpillar", that is the old name, just so you know.
Over the last few days, I've been analyzing an example that combines linear types and effects:
file
"a" write
"b" writeYesterday, I looked into the Write effect. Today, I'd
like to take a stab at the second effect this could trigger. Let's call that one
Error.
If an I/O error happens while writing to a file, then the code doing the writing
could handle the Error effect and react appropriately. If it doesn't handle
the Error effect, and some caller up the chain (maybe the host) does, I think
it's safe to assume that this caller shouldn't resume the code triggering the
effect.
That means we need to take care of file, by putting it into the error (as a
payload), so whoever handles that can take care of disposing or re-using it.
write, which gets control over file anyway, could take care of that under
the hood. So it wouldn't be a problem in this case. But it would be a problem,
if there are other linear types in scope, that are unrelated to this error.
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