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

third_party/bazel/rules_haskell/haskell/private/context.bzl

@@ -0,0 +1,64 @@
+"""Derived context with Haskell-specific fields and methods"""
+
+load("@bazel_skylib//lib:paths.bzl", "paths")
+
+HaskellContext = provider()
+
+def haskell_context(ctx, attr = None):
+    toolchain = ctx.toolchains["@io_tweag_rules_haskell//haskell:toolchain"]
+
+    if not attr:
+        attr = ctx.attr
+
+    if hasattr(attr, "src_strip_prefix"):
+        src_strip_prefix = attr.src_strip_prefix
+    else:
+        src_strip_prefix = ""
+
+    src_root = paths.join(
+        ctx.label.workspace_root,
+        ctx.label.package,
+        src_strip_prefix,
+    )
+
+    env = {
+        "LANG": toolchain.locale,
+    }
+
+    if toolchain.locale_archive != None:
+        env["LOCALE_ARCHIVE"] = toolchain.locale_archive.path
+
+    coverage_enabled = False
+    if hasattr(ctx, "configuration"):
+        coverage_enabled = ctx.configuration.coverage_enabled
+
+    return HaskellContext(
+        # Fields
+        name = attr.name,
+        label = ctx.label,
+        toolchain = toolchain,
+        tools = toolchain.tools,
+        src_root = src_root,
+        package_root = ctx.label.workspace_root + ctx.label.package,
+        env = env,
+        mode = ctx.var["COMPILATION_MODE"],
+        actions = ctx.actions,
+        bin_dir = ctx.bin_dir,
+        genfiles_dir = ctx.genfiles_dir,
+        coverage_enabled = coverage_enabled,
+    )
+
+def render_env(env):
+    """Render environment dict to shell exports.
+
+    Example:
+
+      >>> render_env({"PATH": "foo:bar", "LANG": "lang"})
+      export PATH=foo:bar
+      export LANG=lang
+
+    """
+    return "\n".join([
+        "export {}={}".format(k, v)
+        for k, v in env.items()
+    ])