1 files changed, 67 insertions, 0 deletions
diff --git a/third_party/bazel/rules_haskell/haskell/private/pkg_id.bzl b/third_party/bazel/rules_haskell/haskell/private/pkg_id.bzl
new file mode 100644
index 0000000000..0a3c5fa439
--- /dev/null
+++ b/third_party/bazel/rules_haskell/haskell/private/pkg_id.bzl
@@ -0,0 +1,67 @@
+"""Package identifiers"""
+
+load(":private/mode.bzl", "is_profiling_enabled")
+load("@bazel_skylib//lib:paths.bzl", "paths")
+
+def _zencode(s):
+    """Z-escape special characters to make a valid GHC package identifier.
+
+    Args:
+      s: string
+    """
+    return s.replace("Z", "ZZ").replace("_", "ZU").replace("/", "ZS")
+
+def _to_string(my_pkg_id):
+    """Get a globally unique package identifier.
+
+    The identifier is required to be unique for each Haskell rule.
+    It includes the Bazel package and the name of this component.
+    We can't use just the latter because then two components with
+    the same names in different packages would clash.
+    """
+    return _zencode(
+        paths.join(
+            my_pkg_id.label.workspace_root,
+            my_pkg_id.label.package,
+            my_pkg_id.name,
+        ),
+    )
+
+def _new(label, version = None):
+    """Create a new package identifier.
+
+    Package identifiers should be globally unique. This is why we use
+    a label to identify them.
+
+    Args:
+      label: The label of the rule declaring the package.
+      version: an optional version annotation.
+
+    Returns:
+      string: GHC package ID to use.
+
+    """
+    return struct(
+        label = label,
+        name = label.name.replace("_", "-"),
+        version = version,
+    )
+
+def _library_name(hs, my_pkg_id, prof_suffix = False):
+    """Get library name.
+
+    Args:
+      hs: Haskell context.
+      my_pkg_id: pkg_id struct.
+      prof_suffix: whether to automatically add profiling suffix.
+    """
+    library_name = "HS" + _to_string(my_pkg_id)
+    if is_profiling_enabled(hs) and prof_suffix:
+        library_name += "_p"
+    return library_name
+
+pkg_id = struct(
+    new = _new,
+    to_string = _to_string,
+    library_name = _library_name,
+)