Nushell core team meeting 2023-11-08

Attendees

• Darren
• Antoine
• Ysthakur
• Sophia
• Stefan
• Kubouch
• WindSoilder

Agenda

• invited ysthakur to discuss spread operator
• errors as values
• nu-parser
• exec for windows has landed, but differently

Discussed Topics

Spread operator

https://hackmd.io/@ysthakur/nu-spread

Initial design questions

@ysthakur

• Scoped: only inside list/records/ when calling commands
• What to do with string as the operand of a spread?
  • e.g. python turns it into list like iterator
• What could be potential restrictions

Kubouch:

• I would like it in simple cases:
  • we have some preexisting commands
  • for the command calls it is tricky as we have some times type restriction and some times not. (parsing of …rest list into sane parameters)
  • **kwargs in python would be tricky as we have both positional and keyword arguments mixed

Sophia:

• How to spread mixed type lists
• JS spreading strings feels yucky: what is the sensible unit to split on
  • don't spread strings
  • we have explicit commands e.g. split chars

Detour: destructuring pattern matching in assignment

https://hackmd.io/@ysthakur/nu-spread#Example-3

Q: how to handle errrors if pattern doesn't match. strong assumptions about what the parser returns

good starting point

• spreading in list & record literals sounds straightforward
• Complication in table literal:
  • should it spread to column/row
  • validation
• call site would need some look into the type/checking
• crawl/walk/run

Syntax

... used in existing ...rest params

.. for match => should probably change at some point for consistency in a separate PR

..$var can be confused with a range

Go with ... for spread

Errors as Values

Errors are behaving pretty much like exceptions (raise out if they are part of a pipeline, get caught by try/catch)

Could Errors be just a tagged version of a record -> destructurable (opposite of error make)

JT:

match $foo {
  error { msg, start, end } => {
    print $msg
  }
}

• this would disfavour enum like error style internally: we don't have enums in Nu atm
• error/codes link
  Kubouch: give this record in the closure args of the catch block
• we currently pass the Value::Error which would immediately reraise taking it out of the argument
• implement serialization and this would become usable

new-nu-parser

has been on the backburner but slow and steady we will move forward

exec for windows

• unix side will still behave the same
• IanManske, ChrisDenton, Darren workshopped how Windows works
  • behavior should follow how cargo solve the problem for win
  • Darren hopes that in the future we could replace a running nushell with the new version after an update

Issues

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the issues which needs-core-team-attention

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Note
to list all the PRs currently opened in nushell/nushell:

gh pr list --json url,number,author,title
| from json
| each {|i|
    $"- [($i.number)]\(($i.url)\) ($i.title) \(@($i.author.login)\)"
}
| reverse
| to text