Darcs is a distributed version control system (DVCS) that is focuses on patches instead of snapshots. At the time of writing, Nix flakes does not & cannot support Darcs input pinning requiring an input pinner like Nixtamal to automate it.

How to pin a Darcs repository with Nix + Nixtamal using htmlq

Let’s test the Darcs support by pinning darcsden, which is what runs darcs hub and can be used to self host your own darcs repositories.

Latest change from hub.darcs.net using htmlq 

// manifest.kdl
inputs {
	darcsden {
		darcs {
			repository "https://hub.darcs.net/simon/darcsden"
		}
		fresh-cmd {
			$ curl -sL https:
			| htmlq -t entry:first-of-type id
		}
	}
}