>This project is a heavy WIP and not ready to be used. The name is also very WIP, please give me recommendations.

# ezshell
Standalone semi-implementation of devenv's `languages` feature.

## Install (flake)
```nix
inputs.ezshell.url = "git+https://tangled.org/poacher.dev/ezshell";
inputs.ezshell.inputs.nixpkgs.follows = "nixpkgs";
```

## Basic usage
`ezshell.lib.withLangs` determines `system`/`pkgs` itself from whatever
systems appear in `languages`:

```nix
{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    ezshell.url = "git+https://tangled.org/poacher.dev/ezshell";
  };
  outputs = {nixpkgs, ezshell, ...}: let
    system = "x86_64-linux";
  in ezshell.lib.withLangs {
    languages.${system} = {
      rust.enable = true;
      python = {
        enable = true;
        version = "3.11"; # -> python311
      };
    };
  };
}
```

```
$ nix develop
$ python --version
$ cargo --version
```

## Composing with an existing devShell
`withLangs` takes any flake-outputs-shaped attrset and merges into it.
Your existing devShells are preserved via. 

```nix
ezshell.lib.withLangs {
  devShells.${system}.default = pkgs.mkShellNoCC {
    packages = [pkgs.postgresql];
  };
  languages.${system}.python.enable = true;
}
```

## Git hooks (optional)
`withLangs` always generates a `nixhooks.hooks.${system}` attrset as part of
its output in the shape expected by [nixhooks](https://tangled.org/poacher.dev/nixhooks),
so you can compose it with ezshell:

```nix
{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    ezshell.url = "git+https://tangled.org/poacher.dev/ezshell";
    nixhooks.url = "git+https://tangled.org/poacher.dev/nixhooks";
  };
  outputs = {nixpkgs, ezshell, nixhooks, ...}: let
    system = "x86_64-linux";
  in nixhooks.lib.withHooks (ezshell.lib.withLangs {
    languages.${system}.rust.enable = true;
  });
}
```

```
$ nix develop         # git hooks install automatically
$ nix run .#run-hooks # manually install hooks
```

## Reaching into resolved options
Both `withLangs` and `mkLangs` always include every language's fully resolved
options in their result under `languages`. 

In a flake, you may reach it through `self`:

```nix
{
  outputs = {self, nixpkgs, ezshell, ...}: ezshell.lib.withLangs {
    languages.${system}.nix.enable = true;

    checks.${system}.fmt-check = pkgs.runCommand "fmt-check" {} ''
      ${pkgs.lib.getExe self.languages.${system}.nix.formatter.package} --check ${./.}
      touch $out
    '';
  };
}
```

## Manual, single-system use
`ezshell.lib.${system}.mkLangs` is also available directly, for lower-level
per-system control:

```nix
let
  result = ezshell.lib.${system}.mkLangs {
    languages.python.enable = true;
  };
in
  result.languages.python.package
```

## Non-flake usage
Vendor your own `nixpkgs` and `adios`, then use `mkLangs`:
Non-flake usage only gets `mkLangs`, so you need to build the devShell yourself:

```nix
let
  pkgs = import <nixpkgs> {};
  adios = import (import ./npins).lladios; 
  ezshell = import (fetchTarball "https://tangled.org/poacher.dev/ezshell/archive/main.tar.gz") {
    inherit pkgs adios;
  };
  result = ezshell.mkLangs {
    languages.python.enable = true;
  };
in
  pkgs.mkShellNoCC {packages = result.packages;}
```