Julian Amarilla 7fcebf37ec
Fix #15440 default --empty fails at empty streams (#15562)
Fixes #15440 

# Description
Wraps ListStream stream type from `impl Iterator` to `Peekable<impl
Iterator>`, this allows checking for empty streams and treating them as
empty values
 
Example:
```
# previously
$ glob ? | default -e void
> # empty list

$ echo '' | default -e void
> void

####################

# now
$ glob ? | default -e void
> void

$ echo '' | default -e void
> void
```

# User-Facing Changes

empty list streams will behave as `nothing` values when testing for
emptiness

# Tests + Formatting

- Add 2 tests
- clippy OK
- fmt OK

# After Submitting
2025-04-17 16:57:25 +02:00
..
2025-04-06 09:49:28 +08:00
2025-04-06 09:49:28 +08:00
2025-04-08 08:51:12 +08:00
2025-04-07 13:36:23 +02:00
2025-04-06 09:49:28 +08:00
2025-04-06 09:49:28 +08:00
2022-02-07 14:54:06 -05:00

Nushell core libraries and plugins

These sub-crates form both the foundation for Nu and a set of plugins which extend Nu with additional functionality.

Foundational libraries are split into two kinds of crates:

  • Core crates - those crates that work together to build the Nushell language engine
  • Support crates - a set of crates that support the engine with additional features like JSON support, ANSI support, and more.

Plugins are likewise also split into two types:

  • Core plugins - plugins that provide part of the default experience of Nu, including access to the system properties, processes, and web-connectivity features.
  • Extra plugins - these plugins run a wide range of different capabilities like working with different file types, charting, viewing binary data, and more.