made two delimiter modes

lm_eval/api/samplers.py

@@ -33,7 +33,9 @@ class Sampler:
             self.delimiter.join(
                 [
                     # TODO: is separating doc_to_text and doc_to_target by one space always desired?
-                    self.task.doc_to_text(doc) + " " + self.task.doc_to_target(doc)
+                    self.task.doc_to_text(doc)
+                    + self.config.sample_delimiter
+                    + self.task.doc_to_target(doc)
                     for doc in selected_docs
                 ]
             )

lm_eval/api/task.py

@@ -76,7 +76,8 @@ class TaskConfig(dict):
     gold_alias: Union[Callable, str] = None
     output_type: str = "greedy_until"
     generation_kwargs: dict = None
-    delimiter: str = "\n\n"
+    target_delimiter: str = "\n\n"
+    sample_delimiter: str = " "
     filter_list: Union[str, list] = None
     should_decontaminate: bool = False
     doc_to_decontamination_query: str = None