Bazel steward experiment

WORKSPACE

@@ -93,14 +93,41 @@ rules_jvm_external_setup()
 # deps - TODO: how to put this section into a separate file? do we need a repository_rule for that?
 
 load("@rules_jvm_external//:defs.bzl", "maven_install")
+load("@rules_jvm_external//:specs.bzl", "maven")
+load("//deps:extensions.bzl", "derive", "java", "scala")
+
+slf4j_version = "2.0.7"
+
+logback_version = "1.4.14"
 
 maven_install(
     name = "maven",
-    artifacts = [
-        "ch.qos.logback:logback-classic:1.4.14",
-        "com.typesafe.scala-logging:scala-logging_2.12:3.9.5",
-        "org.slf4j:slf4j-api:2.0.7",
-    ],
+    artifacts = derive(
+        [
+            scala("eu.timepit:fs2-cron-cron4s:0.8.3"),
+            java(
+                "org.slf4j:slf4j-api:%s" % slf4j_version,
+            ),
+            java(
+                maven.artifact(
+                    artifact = "logback-classic",
+                    exclusions = [
+                        "org.slf4j:slf4j-log4j12",
+                    ],
+                    group = "ch.qos.logback",
+                    version = logback_version,
+                ),
+            ),
+            scala(
+                maven.artifact(
+                    "com.typesafe.scala-logging",
+                    "scala-logging",
+                    "3.9.4",
+                ),
+            ),
+        ],
+        ["2.12"],
+    ),
     fail_if_repin_required = True,
     fail_on_missing_checksum = True,
     fetch_javadoc = True,

deps/extensions.bzl

@@ -0,0 +1,37 @@
+load("@rules_jvm_external//:specs.bzl", "parse")
+
+def wrap(things, args = []):
+    return things
+
+def add_scala_version(object, version):
+    if type(object) == "string":
+        parsed = parse.parse_maven_coordinate(object)
+        parsed["artifact"] = parsed["artifact"] + "_" + version
+        return parsed
+    else:
+        object["artifact"] = object["artifact"] + "_" + version
+        return object
+
+def scala(object_or_name):
+    return ("scala", object_or_name)
+
+def java(object_or_name):
+    return ("java", object_or_name)
+
+def _handle_entry(tagged_artifact, scala_version):
+    if type(tagged_artifact) != "tuple":
+        fail("Expected tuple, got string - did you wrap with scala() or java()?")
+    (lang, artifact) = tagged_artifact
+    if lang == "scala":
+        return add_scala_version(artifact, scala_version)
+    else:
+        return artifact
+
+def derive(items, scala_versions):
+    artifacts = []
+    for item in items:
+        #        if type(item) == "string":
+        #            item = ("java", item)
+        derived = [_handle_entry(item, ver) for ver in scala_versions]
+        artifacts.extend(derived)
+    return artifacts