travis: use recent nixpkgs channel (20.09) to install dependencies

1 files changed, 24 insertions, 0 deletions

diff --git a/custom.nix b/custom.nix
new file mode 100644
index 0000000..f8fe7ce
--- /dev/null
+++ b/custom.nix
@@ -0,0 +1,24 @@
+{ pkgs ? import <nixpkgs> {} }: with pkgs;
+
+let
+  mkDhallVersion =
+    version: sha256:
+      stdenv.mkDerivation {
+        name = "dhall-${version}";
+        inherit version;
+        src = fetchurl {
+          url = "https://github.com/dhall-lang/dhall-haskell/releases/download/${version}/dhall-${version}-x86_64-linux.tar.bz2";
+          inherit sha256;
+        };
+        unpackPhase = ''
+          tar -xjf $src
+        '';
+        installPhase = ''
+          mkdir -p $out/bin
+          mv bin/dhall $out/bin/
+        '';
+      };
+in
+{
+  dhall = mkDhallVersion "1.34.0" "0n64jkgbv7a3cmlv3gxpgc11p9b5w0k9nc0zm9am2pzmp6vm6b4n";
+}