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https://github.com/sambacha/nix-linguist
Legacy GitHub Linguist Grammar for Nix
https://github.com/sambacha/nix-linguist
flakes github linguist nix nix-flakes nix-language nix-shell nixos syntax
Last synced: 3 months ago
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Legacy GitHub Linguist Grammar for Nix
- Host: GitHub
- URL: https://github.com/sambacha/nix-linguist
- Owner: sambacha
- License: other
- Created: 2022-06-26T12:31:18.000Z (over 2 years ago)
- Default Branch: master
- Last Pushed: 2023-07-09T16:11:58.000Z (over 1 year ago)
- Last Synced: 2024-10-12T08:14:20.577Z (4 months ago)
- Topics: flakes, github, linguist, nix, nix-flakes, nix-language, nix-shell, nixos, syntax
- Language: TypeScript
- Homepage: https://github.com/nix-community/tree-sitter-nix
- Size: 86.9 KB
- Stars: 4
- Watchers: 2
- Forks: 0
- Open Issues: 5
-
Metadata Files:
- Readme: README.md
- License: LICENSE.txt
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README
# [nix-linguist](https://nixos.org/)
> **Warning**
> As of July 2023, GitHub Linguist has began adopting tree-sitter based grammars.
> [The Nix Community now maintains the relevant language grammar](https://github.com/nix-community/tree-sitter-nix)
> https://github.com/github-linguist/linguist/commit/e855ef2b6f90c34074061a2e17acbe853e61b483
> **Note**
> The _Legacy_ GitHub Linguist Grammar for Nix
- [nix-linguist](https://nixos.org/)
* [Overview](#overview)
- [Nix](#nix)
* [Language constructs](#language-constructs)
* [Primitives / literals](#primitives---literals)
* [Operators](#operators)
- [Canonical Nix Grammar](#canonical-nix-grammar)
- [Nix BNF Grammar](#nix-bnf-grammar)
## Overview
This repo provide's GitHub's Linguist with a grammar file to enhance syntax highlighting when viewed on `github.com`.
> **Warning**
> As such, for other parsing usages, this syntax file should not be used as it is lax (not strict).
# Nix
> **Note**
> [source, nixery 1pager](https://nixery.dev/nix-1p.html)
- **purely functional**. It has no concept of sequential steps being executed, any dependency between operations is established by depending on _data_ from previous operations.
Everything in Nix is an expression, meaning that every directive returns some kind of data.
Evaluating a Nix expression _yields a single data structure_, it does not execute a sequence of operations.
Every Nix file evaluates to a _single expression_.
- **lazy**. It will only evaluate expressions when their result is actually requested.
For example, the builtin function `throw` causes evaluation to stop. Entering the following expression works fine however, because we never actually ask for the part of the structure that causes the `throw`.
```nix
let attrs = { a = 15; b = builtins.throw "Oh no!"; };
in "The value of 'a' is ${toString attrs.a}"
```
- **purpose-built**. Nix only exists to be the language for Nix, the package manager. While people have occasionally used it for other use-cases, it is explicitly not a general-purpose language.
## [Language constructs](#)
This section describes the language constructs in Nix. It is a small language and most of these should be self-explanatory.
## [Primitives / literals](#)
Nix has a handful of data types which can be represented literally in source code, similar to many other languages.
```nix
# numbers
42
1.72394
# strings & paths
"hello"
./some-file.json
# strings support interpolation
"Hello ${name}"
# multi-line strings (common prefix whitespace is dropped)
''
first line
second line
''
# lists (note: no commas!)
[ 1 2 3 ]
# attribute sets (field access with dot syntax)
{ a = 15; b = "something else"; }
# recursive attribute sets (fields can reference each other)
rec { a = 15; b = a * 2; }
```
## [Operators](#)
Nix has several operators, most of which are unsurprising:
| Syntax | Description |
| --- | --- |
| `+`, `-`, `*`, `/` | Numerical operations |
| `+` | String concatenation |
| `++` | List concatenation |
| `==` | Equality |
| `>`, `>=`, `<`, `<=` | Ordering comparators |
| `&&` | Logical `AND` |
| `||` | Logical `OR` |
| `e1 -> e2` | Logical implication (i.e. `!e1 || e2`) |
| `!` | Boolean negation |
| `set.attr` | Access attribute `attr` in attribute set `set` |
| `set ? attribute` | Test whether attribute set contains an attribute |
| `left // right` | Merge `left` & `right` attribute sets, with the right set taking precedence |
Make sure to understand the `//`\-operator, as it is used quite a lot and is probably the least familiar one.
#### Canonical Nix Grammar
[canonical grammar for `nix` can be sourced via NixOS/nix/blob/master/src/libexpr/lexer.l](https://github.com/NixOS/nix/blob/master/src/libexpr/lexer.l#L27-#L314)
#### Nix BNF Grammar
[Another grammar spec format is available in BNF format, here is the grammar file.](https://github.com/NixOS/nix-idea/blob/4d710f3c2a33f70e0057a35b2bab9917cffbdb57/src/main/lang/Nix.bnf)
---
[](https://builtwithnix.org)
[via the MIT License](LICENSE.txt)