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nixpkgs/pkgs/build-support/dhall-to-nix.nix
2019-09-08 23:38:31 +00:00

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Nix

/* `dhallToNix` is a utility function to convert expressions in the Dhall
configuration language to their corresponding Nix expressions.
Example:
dhallToNix "{ foo = 1, bar = True }"
=> { foo = 1; bar = true; }
dhallToNix "λ(x : Bool) x == False"
=> x : x == false
dhallToNix "λ(x : Bool) x == False" false
=> true
See https://hackage.haskell.org/package/dhall-nix/docs/Dhall-Nix.html for
a longer tutorial
Note that this uses "import from derivation", meaning that Nix will perform
a build during the evaluation phase if you use this `dhallToNix` utility
*/
{ stdenv, dhall-nix }:
let
dhallToNix = code :
let
file = builtins.toFile "dhall-expression" code;
drv = stdenv.mkDerivation {
name = "dhall-compiled.nix";
buildCommand = ''
dhall-to-nix <<< "${file}" > $out
'';
buildInputs = [ dhall-nix ];
};
in
import drv;
in
dhallToNix