wta: Make --different-values optional

It doesn't make much sense for powerset, so now it's possible to omit it.

wta/bench.py

@@ -11,14 +11,18 @@ import scipy.stats as st
 samples = 5
 
 
+def from_maybe(default, x):
+    return default if x is None else x
+
+
 # Edge Spec should be ("transitions", str) or ("zero-frequency", str)
 def coalg_file(states, monoid, symbols, edge_spec, different_values, i):
     if edge_spec[0] == "transitions":
         return "bench/wta_%s_%s_t%s_%s_%s_%d" % (monoid, symbols, edge_spec[1],
-                                         different_values, states, i)
+                                         from_maybe("", different_values), states, i)
     else:
         return "bench/wta_%s_%s_%s_%s_%s_%d" % (monoid, symbols, edge_spec[1],
-                                         different_values, states, i)
+                                         from_maybe("", different_values), states, i)
 
 
 def check_zerotrans(args):
@@ -54,6 +58,7 @@ def generate(args):
 
         cmd = [generator, "--states", states, "--monoid", monoid, "--symbols", symbols]
         cmd += ["--" + edge_spec[0], edge_spec[1]]
+        if not (different_values is None):
             cmd += ["--different-values", different_values]
             
         subprocess.run(cmd, stdout=open(f, "w+"))
@@ -82,7 +87,7 @@ def run_one(args, i):
     stats['monoid'] = monoid
     stats['symbols'] = symbols
     stats['edge-spec'] = str(edge_spec)
-    stats['mon-values'] = different_values
+    stats['mon-values'] = from_maybe("", different_values)
     stats['i'] = i
 
     return stats
@@ -257,7 +262,7 @@ def main():
     gen_parser.add_argument('--symbols', required=True)
     gen_parser.add_argument('--zero-frequency')
     gen_parser.add_argument('--transitions')
-    gen_parser.add_argument('--different-values', required=True)
+    gen_parser.add_argument('--different-values')
     gen_parser.set_defaults(func=generate)
 
     run_parser = subparsers.add_parser('run')
@@ -267,7 +272,7 @@ def main():
     run_parser.add_argument('--symbols', required=True)
     run_parser.add_argument('--zero-frequency')
     run_parser.add_argument('--transitions')
-    run_parser.add_argument('--different-values', required=True)
+    run_parser.add_argument('--different-values')
     run_parser.add_argument(
         '--stddev', action='store_true', help="report stddev for timings")
     run_parser.add_argument(
@@ -283,7 +288,7 @@ def main():
     bisect_parser.add_argument('--symbols', required=True)
     bisect_parser.add_argument('--zero-frequency')
     bisect_parser.add_argument('--transitions')
-    bisect_parser.add_argument('--different-values', required=True)
+    bisect_parser.add_argument('--different-values')
     bisect_parser.add_argument('--start-states', type=int, default=50)
     bisect_parser.add_argument('--good', type=int)
     bisect_parser.add_argument('--bad', type=int)