language: support setting slices of data in mutate_dataset

artiq/language/environment.py

@@ -286,7 +286,12 @@ class HasEnvironment:
         a given position in a NumPy array)
 
         If the dataset was created in broadcast mode, the modification is
-        immediately transmitted."""
+        immediately transmitted.
+
+        If the index is a tuple of integers, it is interpreted as
+        ``slice(*index)``.
+        If the index is a tuple of tuples, each sub-tuple is interpreted
+        as ``slice(*sub_tuple)`` (multi-dimensional slicing)."""
         self.__dataset_mgr.mutate(key, index, value)
 
     def get_dataset(self, key, default=NoDefault):

artiq/master/worker_db.py

@@ -1,3 +1,4 @@
+from operator import setitem
 from collections import OrderedDict
 import importlib
 import logging
@@ -194,7 +195,13 @@ class DatasetManager:
             target = self.broadcast[key][1]
         if target is None:
             raise KeyError("Cannot mutate non-existing dataset")
-        target[index] = value
+
+        if isinstance(index, tuple):
+            if isinstance(index[0], tuple):
+                index = tuple(slice(*e) for e in index)
+            else:
+                index = slice(*index)
+        setitem(target, index, value)
 
     def get(self, key):
         if key in self.local: