# Nushell core team meeting 2024-05-08
## Attendees
- Darren
- Devyn
- Michael
- Andy
- Jakub
- Filip
- Wind
- Stefan
- Woossaaahh
- Antoine
- Ian
- Jack

## Agenda
- [x] Proposal: Remove `str contains --not` flag (redundant since we have `not` operator)
- context: https://github.com/nushell/nushell/pull/12781#issuecomment-2097688044
- [x] redirection of string(stream) like POSIX stream to file
- Ian's proposed PR making that external only: https://github.com/nushell/nushell/pull/12785
- Issue desiring the ability to redirect `print (-e)`: https://github.com/nushell/nushell/issues/12686
- [x] Stream refactor
- Error handling
- [ ] [Command spring cleaning](/QyUBRm5fQiKeRNHv4rZBYw)
- [x] Lightning topic: MIME commands and `ls --mime-type`
- [ ] Table values and streams (possibly next meeting instead)

## Discussed Topics

## `--not` on `str contains`
- Jakub: should not add `--not` flag to every command that returns a bool
- challenge to keep consistent and would escalate
- Darren `not (check)` is a bit wordy
- Devyn: `is-not-empty` is one of the frequently used cases where the ceremony would be annoying
- `not` is an operator so it can't really act like a regular command
- `| not $in` should work already (thx Ian for pointing this out)
- `| not` would be slightly more elegant (would require some parser hacking because `not` is an operator)

## redirection of string(stream) like POSIX stream to file

Should we reserve `out>` for externals only?

- We kind of have `out>` doing multiple things potentially, going from a string stream to a file would be very straightforward, but `print` doesn't produce a string stream
- Darren: don't want to forbid redirecting external streams, more inconsistency not great
- Side-challenge: missing `err>null` and `err> /dev/null` is not cross-platform
- `out> file` is faster for externals because the OS can do it
- maybe we're not going to resolve this today
- should we do a poll?
- kubouch: only `o>` and `o>>` should work for nushell internal values, `o>|` is a noop = `|`
- kubouch: manual wrappers around external commands how would this play with redirect?
- file redirections create a scope, all external commands inside the expression use the file redirection
- Wind: User expecting `echo "aaa" o> file.txt`
- we will create one inconsistency anyways > try to find the minimal pain, easiest to explain way
- Jack: `o+e>` would break if we disallow values and you may encounter a situation where there is an external emitting STDERR in your previous pipeline step.
- error stream could be a future think to talk about
- Conclusion for #12785: improve the error message, try out, gather user feedback

Separate track `print` and internal `eprintln!`s
- We can't support things like `print err>` or `print out>` already, so it's important that people understand the difference
- Since we now know what the redirection state (`OutDest`) is from the `Stack`, it's actually possible for `print` to support this. Maybe we can be consistent
- more thought/analysis needed (out of scope for now)

## Stream refactor

- Ian working on ByteStream, which replaces ExternalStream with a generalized single stream type that can be more easily used by internal commands too
- PR: https://github.com/nushell/nushell/pull/12774
- exit code changes have been factored out (would have been a breaking change)
- Devyn already on top building a type-flavour:
- mark if it is a utf-8 stream or unknown encoding and internals can also enforce binary
- Unknown (from external)
- String (all operations can be sure about utf-8 encoding)
- Binary (explicit will show hexdump)
- [plus adding this to some internal commands already](/4lHUs6Q3Q9iu7wek2xlSdw)

## MIME type commands

- This is a lot to stabilize? The crate we're using doesn't guarantee output stability
- https://docs.rs/mime_guess/latest/mime_guess/#note-mime-types-returned-are-not-stableguaranteed
- HTTP commands accept any mime type but really only do something special for JSON
- For the PR: this could be a plugin, and maybe we just remove `ls --mime-type`
- Maybe just leave things as they are. It's cool to have `ls --mime-type`
- PR: https://github.com/nushell/nushell/pull/12695 -> plugin