Nickel Getting Started

https://nickel-lang.org/getting-started/
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Documentation for Nickel, a configuration language, explaining how to get started, install, and...
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### Install Nickel with Homebrew

Source: https://nickel-lang.org/getting-started

On macOS, use Homebrew to install the Nickel binary. After installation, start an interactive session by running `nickel repl`.

```bash
brew install nickel
nickel repl
nickel> 
```

--------------------------------

### Install Nickel with Nix

Source: https://nickel-lang.org/getting-started

Install the Nickel binary globally using `nix profile install` for more extensive use. After installation, you can run `nickel repl` to start an interactive session.

```bash
nix profile install nixpkgs#nickel
nickel repl
nickel> 
```

--------------------------------

### Install Nickel with Cargo

Source: https://nickel-lang.org/getting-started

For Rust developers, install the Nickel CLI using Cargo. This command fetches and builds the `nickel-lang-cli` crate. Afterwards, run `nickel repl` to enter the interactive mode.

```bash
cargo install nickel-lang-cli
nickel repl
nickel> 
```

--------------------------------

### Run Nickel REPL with Nix

Source: https://nickel-lang.org/getting-started

Use `nix run` to execute Nickel directly from Nixpkgs, passing `repl` as an argument to start an interactive session. Requires Nix version 2.4.0 or higher and experimental features enabled.

```bash
nix run --experimental-features "flakes nix-command" nixpkgs#nickel -- repl
nickel> 
```

--------------------------------

### Basic Nickel Configuration Record

Source: https://nickel-lang.org/getting-started

This snippet demonstrates a basic Nickel configuration for a fictional app, showcasing records, strings, multiline strings, arrays, and nested objects. It's useful for defining application metadata, scripts, and dependencies.

```nickel
{
name = "example",
description = m%"
This is an awesome software I'm developing.
Please use it!
"%,
version = "0.1.1",
main = "index.js",
keywords = ["example", "config"],
scripts = {
test = m%"
test.sh --option --install example --version \"0.1.1\"
"%,
do_stuff = "do_stuff.sh subcommand",
},
contributors = [{
name = "John Doe",
email = "johndoe@example.com"
}, {
name = "Ivy Lane",
url = "https://example.com/ivylane"
}],
dependencies = {
dep1 = "^1.0.0",
dep3 = "6.7"
}
}
```

--------------------------------

### Run Nickel REPL with Docker

Source: https://nickel-lang.org/getting-started

Use Docker to run a Nickel REPL session from a specified image. The `--rm` flag ensures the container is removed after exit, and `-it` provides an interactive terminal.

```bash
docker run --rm -it ghcr.io/tweag/nickel:1.10.0 repl
nickel> 
```

--------------------------------

### Export Nickel Configuration to YAML

Source: https://nickel-lang.org/getting-started

Exports a Nickel configuration file to YAML format. This is useful for generating static configuration files.

```bash
nickel export example.ncl --format yaml
```

```yaml
---
contributors:
  - email: johndoe@example.com
    name: John Doe
  - name: Ivy Lane
    url: https://example.com/ivylane
dependencies:
  dep1: ^1.0.0
  dep3: "6.7"
description: "This is awesome software I'm developing.\nPlease use it!"
keywords:
  - example
  - config
main: index.js
name: example
scripts:
  do_stuff: do_stuff.sh subcommand
  test: "test.sh --option --install example --version \"0.1.1\""
version: 0.1.1

```

--------------------------------

### Import YAML into Nickel Configuration

Source: https://nickel-lang.org/getting-started

Imports data from a YAML file into a Nickel configuration. This allows for gradual migration of existing configuration files.

```nickel
{
  # [...] 
  scripts = {
    test = m%" 
      test.sh --option --install example --version "0.1.1"
    "%,
    do_stuff = "do_stuff.sh subcommand",
  },
  contributors = import "contributors.yaml",
  # [...] 
}

```

--------------------------------

### Reuse Values with String Interpolation in Nickel

Source: https://nickel-lang.org/getting-started

Demonstrates reusing values like 'name' and 'version' within other fields, such as 'scripts.test', using string interpolation. This ensures consistency when values are updated.

```nickel
name = "example",
version = "0.1.1",
scripts = {
  test = m%" 
    test.sh --option --install %{name} --version "%{version}"
  "%,

```

--------------------------------

### Updated Configuration After Version Bump

Source: https://nickel-lang.org/getting-started

Shows the resulting configuration after updating the 'version' field and how string interpolation automatically updates related fields like 'scripts.test'.

```yaml
# [...] 
scripts:
  do_stuff: do_stuff.sh subcommand
  test: "test.sh --option --install example --version \"0.1.2\""
version: 0.1.2

```
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