# Command line tools

To install the command line tools refer to the [Installing nix-tools](https://input-output-hk.github.io/haskell.nix/dev/manually-generating-nix-expressions/) section.

## stack-to-nix

```
stack-to-nix - a stack to nix converter

Usage: stack-to-nix (-o|--output DIR) [--stack-yaml FILE]
                    [--ignore-package-yaml] [--cache FILE]
  Generate a Nix expression for a Haskell package using Stack

Available options:
  -o,--output DIR          Generate output in DIR
  --stack-yaml FILE        Override project stack.yaml (default: "stack.yaml")
  --ignore-package-yaml    disable hpack run and use only cabal disregarding
                           package.yaml existence
  --cache FILE             Dependency cache
                           file (default: ".stack-to-nix.cache")
  -h,--help                Show this help text
```

Use this for stack projects. If a `default.nix` does not exist in the
output directory, it will create a basic one with a
[`mkStackPkgSet`](../manually-generating-nix-expressions#Using-Stack) function.

!!! note
    If you find that there are missing files which should have been
    generated, remove `.stack-to-nix.cache`
    (The open issue is [#57][cache-issue]).

[cache-issue]: https://github.com/input-output-hk/haskell.nix/issues/57

## plan-to-nix

```
plan-to-nix - a stack to nix converter

Usage: plan-to-nix (-o|--output DIR) [--plan-json FILE] [--cabal-project FILE]
                   [--cache FILE]
  Generate a Nix expression for a Haskell package using Cabal

Available options:
  -o,--output DIR          Generate output in DIR
  --plan-json FILE         Override plan.json
                           location (default: "dist-newstyle/cache/plan.json")
  --cabal-project FILE     Override path to
                           cabal.project (default: "cabal.project")
  --cache FILE             Dependency cache file (default: ".nix-tools.cache")
  -h,--help                Show this help text
```

Use this for Cabal new-build projects (even if you don't have a
`cabal.project`). Before running, you need to create a plan. For more
information, see [Cabal Projects](../manually-generating-nix-expressions#Using-Cabal) in the user
guide.

It will create a template `default.nix` in the output directory,
unless that file already exists.

Inside the output directory, there will be another directory
`.plan.nix`, which contains Nix expressions for all local packages,
generated by `cabal-to-nix`. The output file `pkgs.nix` refers to
these files.

!!! note
    If you find that there are missing files which should have been
    generated, remove `.nix-tools.cache`
    (The open issue is [#57][cache-issue]).

## cabal-to-nix

```
Usage: cabal-to-nix FILE.cabal
```

This writes (to stdout) a [Haskell.nix][] Nix expression for the given
cabal package.

Normally, you do not need to run `cabal-to-nix` yourself. It is called
by `stack-to-nix` and `plan-to-nix`.

[haskell.nix]: https://github.com/input-output-hk/haskell.nix