nushell/crates/nu-std/README.md

<h1 align="center">
  Welcome to the standard library of `nushell`!
  <img src="https://media.giphy.com/media/hvRJCLFzcasrR4ia7z/giphy.gif" width="28"></img>
</h1>

The standard library is a pure-`nushell` collection of custom commands which
provide interactive utilities and building blocks for users writing casual scripts or complex applications.

To see what's here:
```
> use std
> scope commands | select name usage | where name =~ "std "
#┬───────────name────────────┬──────────────────────usage──────────────────────
0│std assert                 │Universal assert command
1│std assert equal           │Assert $left == $right
2│std assert error           │Assert that executing the code generates an error
3│std assert greater         │Assert $left > $right
4│std assert greater or equal│Assert $left >= $right
             ...                                     ...
─┴───────────────────────────┴─────────────────────────────────────────────────
```

## :toolbox: Using the standard library in the REPL or in scripts
All commands in the standard library must be "imported" into the running environment
(the interactive read-execute-print-loop (REPL) or a `.nu` script) using the
[`use`](https://nushell.sh/commands/docs/use.html) command.

You can choose to import the whole module, but then must refer to individual commands with a `std` prefix, e.g:
```nushell
use std

std log debug "Running now"
std assert (1 == 2)
```
Or you can enumerate the specific commands you want to import and invoke them without the `std` prefix.
```nushell
use std ["log debug" assert]

log debug "Running again"
assert (2 == 1)
```
This is probably the form of import you'll want to add to your `env.nu` for interactive use.

## :pencil2: contribute to the standard library
You're invited to contribute to the standard library! See [CONTRIBUTING.md] for details

[CONTRIBUTING.md]: https://github.com/nushell/nushell/blob/main/crates/nu-std/CONTRIBUTING.md