nim_lk/README.md

# Nim lockfile generator

Generates Nix specific lock files for Nim packages.

It puts your dependencies in the Nix store where they belong.

```sh
cd «Nim project with a Nimble file»
nim_lk > lock.json
```

These lock files contain Nix FOD store paths that can be converted to `nim.cfg` files.

```nix
{ pkgs ? import <nixpkgs> { }, lockPath }:
let inherit (pkgs) lib;
in lib.pipe lockPath [
  builtins.readFile
  builtins.fromJSON
  (builtins.getAttr "depends")
  (map ({ path, srcDir, ... }: ''path:"${path}/${srcDir}"''))
  lib.strings.concatLines
  (pkgs.writeText "nim.cfg")
]
```

I manage all this with [Tup](https://gittup.org/tup).

```
# Tuprules.tup above my Nim projects
!nim_lk = |> nim_lk > %o |> lock.json

NIXEXPRS_DIR = $(TUP_CWD)/nixexprs
!nim_cfg = |> nix build --file $(NIXEXPRS_DIR)/configure.nix --argstr lockPath `pwd`/%f --out-link %o |> nim.cfg
```

```
# Tupfile in a Nim project
include_rules
: |> !nim_lk |> | ./<lock>
: lock.json |> !nim_cfg |> | ./<lock>
```