nushell/crates/nu-std/README.md
Stefan Holderbach c5aa15c7f6
Add top-level crate documentation/READMEs (#12907)
# Description
Add `README.md` files to each crate in our workspace (-plugins) and also
include it in the `lib.rs` documentation for <docs.rs> (if there is no
existing `lib.rs` crate documentation)

In all new README I added the defensive comment that the crates are not
considered stable for public consumption. If necessary we can adjust
this if we deem a crate useful for plugin authors.
2024-07-14 10:10:41 +02:00

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2.2 KiB
Markdown

<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:
```text
> 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