1 files changed, 124 insertions, 0 deletions
diff --git a/third_party/bazel/rules_haskell/start b/third_party/bazel/rules_haskell/start
new file mode 100755
index 000000000000..24f300cb6ec9
--- /dev/null
+++ b/third_party/bazel/rules_haskell/start
@@ -0,0 +1,124 @@
+#!/bin/sh
+
+MIN_BAZEL_MAJOR=0
+MIN_BAZEL_MINOR=24
+
+set -e
+
+check_files_dont_exist () {
+    if [ -e WORKSPACE ] || [ -e BUILD ] || [ -e BazelExample.hs ]
+    then
+        echo "Current directory already has WORKSPACE and/or BUILD and/or BazelExample.hs files." >/dev/stderr
+        exit 1
+    fi
+}
+
+check_bazel_version () {
+    local actual_raw=$(bazel version | egrep '^Build label:' | egrep -o '[0-9.]+')
+
+    IFS=. read actual_major actual_minor actual_patch <<EOF
+$actual_raw
+EOF
+
+    local expected=$MIN_BAZEL_MAJOR.$MIN_BAZEL_MINOR.0
+    local cmp=$expected'\n'$actual
+
+    if ! ( [ "$actual_major" -gt "$MIN_BAZEL_MAJOR" ] || (
+            [ "$actual_major" -eq "$MIN_BAZEL_MAJOR" ] &&
+                [ "$actual_minor" -ge "$MIN_BAZEL_MINOR" ] ) )
+    then
+        echo "Need at least Bazel v${expected}. v${actual_raw} detected." >/dev/stderr
+        exit 1
+    fi
+}
+
+check_files_dont_exist
+check_bazel_version
+
+cat > WORKSPACE <<"EOF"
+# Give your project a name. :)
+workspace(name = "YOUR_PROJECT_NAME_HERE")
+
+# Load the repository rule to download an http archive.
+load(
+    "@bazel_tools//tools/build_defs/repo:http.bzl",
+    "http_archive"
+)
+
+# Download `rules_haskell`.
+# and make it accessible `@io_tweag_rules_haskell`.
+http_archive(
+    name = "io_tweag_rules_haskell",
+    strip_prefix = "rules_haskell-0.8",
+    urls = ["https://github.com/tweag/rules_haskell/archive/v0.8.tar.gz"],
+    sha256 = "431d492a8ee6a110cdf42496181c9d27225dfb997379e64a148eb8e69f272ab7",
+)
+
+load(
+    "@io_tweag_rules_haskell//haskell:repositories.bzl",
+    "haskell_repositories"
+)
+
+# `haskell_repositories()` sets up all bazel dependencies
+# required by `rules_haskell`.
+haskell_repositories()
+
+load(
+    "@io_tweag_rules_haskell//haskell:haskell.bzl",
+    "haskell_register_ghc_bindists",
+)
+
+# Registers a haskell toolchain with a GHC binary
+# downloaded from haskell.org.
+haskell_register_ghc_bindists(version = "8.6.4")
+EOF
+
+cat > BUILD.bazel <<"EOF"
+# Set all target’s visibility in this package to "public".
+package(default_visibility = ["//visibility:public"])
+
+# Load `rules_haskell` rules.
+load(
+    "@io_tweag_rules_haskell//haskell:haskell.bzl",
+    "haskell_toolchain_library",
+    "haskell_library",
+    "haskell_binary",
+)
+
+# `haskell_toolchain_library` can access builtin GHC packages
+# and assign them a bazel target name, so that they
+# can be referenced as dependencies.
+haskell_toolchain_library(name = "base")
+
+# You can add your own libraries with `haskell_library`.
+# haskell_library(
+#     name = "MY_LIBRARY_NAME",
+#     src_strip_prefix = "src",
+#     srcs = glob(['src/**/*.hs']),
+#     deps = [
+#         "base_pkg"
+#     ],
+# )
+
+# An example binary using the Prelude module from the
+# GHC base package, to print the hello world.
+haskell_binary(
+    name = "example",
+    srcs = [":Example.hs"],
+    deps = [":base"],
+)
+EOF
+
+cat > Example.hs <<"EOF"
+module Main where
+
+import Prelude (putStrLn)
+
+main = putStrLn "Hello from rules_haskell!"
+EOF
+
+cat <<"EOF"
+WORKSPACE and initial BUILD files created. To run Bazel and build the example:
+
+    $ bazel run //:example
+EOF