Replace Travis CI with Buildkite

Author: rvl

.buildkite/build.sh

@@ -0,0 +1,38 @@
+#! /usr/bin/env nix-shell
+#! nix-shell --pure -i bash -p nix cabal-install ghc nix-prefetch-scripts
+
+export NIX_PATH="nixpkgs=channel:nixos-19.03"
+
+set -euo pipefail
+
+# This file can interfere with the build.
+# https://github.com/input-output-hk/haskell.nix/issues/57
+rm -f .nix-tools.cache
+
+echo "+++ Cabal configure"
+cabal new-update
+cabal new-configure
+
+echo
+echo "+++ Run stable version of plan-to-nix"
+nix build -f https://github.com/input-output-hk/haskell.nix/archive/master.tar.gz nix-tools -o nt
+./nt/bin/plan-to-nix --output nix1 --plan-json dist-newstyle/cache/plan.json
+
+echo
+echo "+++ Build project"
+nix build -f nix1 nix-tools.components.exes --no-link
+
+echo
+echo "+++ Run tests"
+echo "There are no tests -- https://github.com/input-output-hk/haskell.nix/issues/51"
+
+echo
+echo "+++ Run plan-to-nix again"
+
+nix build -f nix1 nix-tools.components.exes.plan-to-nix
+./result/bin/plan-to-nix --output nix2 --plan-json dist-newstyle/cache/plan.json
+
+echo
+echo "+++ Build project"
+
+nix build -f nix2 nix-tools.components.exes --no-link

.buildkite/pipeline.yml

@@ -0,0 +1,5 @@
+steps:
+  - label: 'Build'
+    command: ./.buildkite/build.sh
+    agents:
+      system: x86_64-linux