garn
garn is a new take on Nix - configured in Typescript rather than the Nix language, and with a nicer and simpler CLI (thanks optparse-applicative!). The repository is here, and the website is here.
I’m mentioning it here because we just added better Haskell support, which makes it now a plausible alternative to managing your Haskell projects with Nix, Stack or Cabal. An example Haskell project:
import * as garn from "https://garn.io/ts/v0.0.18/mod.ts";
import * as pkgs from "https://garn.io/ts/v0.0.18/nixpkgs.ts";
export const project = garn.haskell.mkHaskellProject({
description: "My project",
src: ".",
executables: ["server", "openapi-generation"]
overrideDependencies: {
"servant": "0.19.1"
},
ghcVersion: "ghc94"
}).addExecutable("format")`${pkgs.ormolu}/bin/ormolu --mode inplace $(find . -name '*.hs')`
Which allows for garn build project to build the project, and garn enter project to be in a devshell with cabal, ghc94 and all the dependencies installed, and garn run project.format for formatting all files with ormolu.
(garn init is capable of generating most of that file for you.)
Comparisons
First, compared to all of the options below, garn is much less mature - there’ll be rougher edges or features not yet supported. It’s also still changing very quickly, and backwards compatibility is not, for now, a priority.
-
Cabal: Like Cabal, garn still uses a cabal file, and in fact expects you to
develop with cabal. garn brings in the dependencies itself and makes them
known to ghc/cabal, and they’re snapshot-based rather than resolver-based. In
addition, garn makes it easy to include system (non-Haskell) dependencies, it
sandboxes builds and tests for better reproduciblity (making CI in particular
quite easy); it allows for shared caches; it supports scripts for project
janitoring and management; and it supports devshells. -
Stack: Like Stack, garn uses a snapshot-based approach to dependencies. In
fact, it’s based on the stackage releases. It also supports overriding
versions from Hackage, but not yet from git. Unlike Stack, it allows
specifying system dependencies (non-Haskell dependencies); it sandboxes
builds and tests for better reproduciblity (making CI in particular quite
easy); it allows for shared caches; it supports scripts for project
janitoring and management; and it supports devshells. -
Nix: the focus of garn has been a simplified and more productive user
experience when compared to Nix. A typed language means you can get
autocompletion, documentation, and type errors in your editor, for example.
And, even if Typescript is by no means perfect, it’s much easier to program
in than Nix, so it becomes more fun to abstract away functionality (e.g.: an
addGhcidToProject function). garn “transpiles” to Nix, and Nix can be
embedded in garn, so the choice is not binary.
Feedback appreciated!
If you try it out, please let us know what you think, or if you run into any roadblocks. You can message me or open issues on GitHub, or join the Discord channel at.
It also happens to be partly written in Haskell; hopefully that makes it more easy and fun to get involved!
Cheers,
Julian