feat(third_party/bazel): Check in rules_haskell from Tweag

third_party/bazel/rules_haskell/tests/repl-flags/ReplFlags.hs

@@ -0,0 +1,17 @@
+{-# LANGUAGE CPP #-}
+module Main where
+
+import Data.ByteString
+
+-- Ensure that `compiler-flags` are correctly set
+#ifdef TESTS_TOOLCHAIN_COMPILER_FLAGS
+main = print "hello"
+#endif
+
+-- Ensure that `repl_ghci_args` are correctly set
+-- OverloadedString is passed by toolchain
+-- The CPP constant is unset by toolchain and set by rule, so ordering must be ensured
+#ifdef TESTS_TOOLCHAIN_REPL_FLAGS
+foo = ("world" :: ByteString)
+#endif
+