language,worker: preserve order of arguments

artiq/language/environment.py

@@ -1,3 +1,4 @@
+from collections import OrderedDict
 from inspect import isclass
 
 
@@ -41,7 +42,7 @@ class HasEnvironment:
     parameters, results, arguments)."""
     def __init__(self, dmgr=None, pdb=None, rdb=None, *,
                  param_override=dict(), default_arg_none=False, **kwargs):
-        self.requested_args = dict()
+        self.requested_args = OrderedDict()
 
         self.__dmgr = dmgr
         self.__pdb = pdb

artiq/master/worker_impl.py

@@ -127,8 +127,8 @@ def examine(dmgr, pdb, rdb, file):
                 if name[-1] == ".":
                     name = name[:-1]
             exp_inst = exp_class(dmgr, pdb, rdb, default_arg_none=True)
-            arguments = {k: v.describe()
-                         for k, v in exp_inst.requested_args.items()}
+            arguments = [(k, v.describe())
+                         for k, v in exp_inst.requested_args.items()]
             register_experiment(class_name, name, arguments)