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Crystal
Building a Crystal package
This section uses Mint as an example for how to build a Crystal package.
If the Crystal project has any dependencies, the first step is to get a shards.nix
file encoding those. Get a copy of the project and go to its root directory such that its shard.lock
file is in the current directory, then run crystal2nix
in it
$ git clone https://github.com/mint-lang/mint
$ cd mint
$ git checkout 0.5.0
$ nix-shell -p crystal2nix --run crystal2nix
This should have generated a shards.nix
file.
Next create a Nix file for your derivation and use pkgs.crystal.buildCrystalPackage
as follows:
with import <nixpkgs> {};
crystal.buildCrystalPackage rec {
pname = "mint";
version = "0.5.0";
src = fetchFromGitHub {
owner = "mint-lang";
repo = "mint";
rev = version;
sha256 = "0vxbx38c390rd2ysvbwgh89v2232sh5rbsp3nk9wzb70jybpslvl";
};
# Insert the path to your shards.nix file here
shardsFile = ./shards.nix;
...
}
This won't build anything yet, because we haven't told it what files build. We can specify a mapping from binary names to source files with the crystalBinaries
attribute. The project's compilation instructions should show this. For Mint, the binary is called "mint", which is compiled from the source file src/mint.cr
, so we'll specify this as follows:
crystalBinaries.mint.src = "src/mint.cr";
# ...
Additionally you can override the default crystal build
options (which are currently --release --progress --no-debug --verbose
) with
crystalBinaries.mint.options = [ "--release" "--verbose" ];
Depending on the project, you might need additional steps to get it to compile successfully. In Mint's case, we need to link against openssl, so in the end the Nix file looks as follows:
with import <nixpkgs> {};
crystal.buildCrystalPackage rec {
version = "0.5.0";
pname = "mint";
src = fetchFromGitHub {
owner = "mint-lang";
repo = "mint";
rev = version;
sha256 = "0vxbx38c390rd2ysvbwgh89v2232sh5rbsp3nk9wzb70jybpslvl";
};
shardsFile = ./shards.nix;
crystalBinaries.mint.src = "src/mint.cr";
buildInputs = [ openssl ];
}