2020-01-27 02:55:02 +00:00
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# nu-source
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## Overview
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2020-03-13 17:23:41 +00:00
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The `nu-source` crate contains types and traits used for keeping track of _metadata_ about values being processed.
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2020-01-27 02:55:02 +00:00
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Nu uses `Tag`s to keep track of where a value came from, an `AnchorLocation`,
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as well as positional information about the value, a `Span`.
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2020-03-13 17:23:41 +00:00
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An `AnchorLocation` can be a `Url`, `File`, or `Source` text that a value was parsed from.
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2020-01-27 02:55:02 +00:00
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The source `Text` is special in that it is a type similar to a `String` that comes with the ability to be cheaply cloned.
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A `Span` keeps track of a value's `start` and `end` positions.
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These types make up the metadata for a value and are wrapped up together in a `Tagged` struct,
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2020-03-13 17:23:41 +00:00
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which holds everything needed to track and locate a value.
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2020-01-27 02:55:02 +00:00
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Nu's metadata system can be seen when reporting errors.
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In the following example Nu is able to report to the user where the typo of a column originated from.
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2020-06-23 18:21:47 +00:00
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```shell
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2020-01-27 02:55:02 +00:00
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1 | ls | get typ
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| ^^^ did you mean 'type'?
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```
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2020-03-13 17:23:41 +00:00
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In addition to metadata tracking, `nu-source` also contains types and traits
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related to debugging, tracing, and formatting the metadata and values it processes.
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2020-01-27 02:55:02 +00:00
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## Other Resources
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2020-06-23 18:21:47 +00:00
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2020-03-13 17:23:41 +00:00
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- [Nushell Github Project](https://github.com/nushell):
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Contains all projects in the Nushell ecosystem such as the source code to Nushell as well as website and books.
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- [Nushell Git Repository](https://github.com/nushell/nushell):
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A direct link to the source git repository for Nushell
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- [Nushell Contributor Book](https://github.com/nushell/contributor-book):
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An overview of topics about Nushell to help you get started contributing to the project.
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2020-01-27 02:55:02 +00:00
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- [Discord Channel](https://discordapp.com/invite/NtAbbGn)
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2020-06-23 18:21:47 +00:00
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- [Twitter](https://twitter.com/nu_shell)
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