funflow-nix provides functions for creating flows which run in a nix environment.

The library exposes the NixConfig data type which allows you to specify the environment and command to run. This is then turned into a flow using nix.

A complete example can be seen in examples/Simple.hs.

We can pin the version of nixpkgs we want to use by specifying a tarball to use as the source.

tarballSource :: NixpkgsSource
tarballSource = NixpkgsTarball [uri|https://github.com/NixOS/nixpkgs/archive/a19357241973538212b5cb435dde84ad25cbe337.tar.gz|]

nixConfig :: Environment -> NixConfig
nixConfig senv =
  NixShellConfig {
    environment = senv
    , command = "jq"
    , args = [ParamText "--version"]
    , env = []
    , stdout = StdOutCapture
    , nixpkgsSource = tarballSource
  }

Once the config has been specified. It can be turned into a flow by using the nix function.

jqVersionPkg :: SimpleFlow () String
jqVersionPkg = readString_ <<< nix (\() -> nixConfig (PackageList ["jq"]))