Arm the REPL with a customized tree printer

src/python/flowmetal/repl.py

@@ -3,7 +3,6 @@
 import argparse
 import logging
 import sys
-import pprint
 
 from flowmetal.syntax_analyzer import analyzes
 
@@ -25,20 +24,42 @@ class InterpreterInterrupt(Exception):
     """An exception used to break the prompt or evaluation."""
 
 
+def pp(t, indent=""):
+    if isinstance(t, list):  # lists
+        buff = ["["]
+        for e in t:
+            buff.append(f"{indent}  " + pp(e, indent+"  ")+",")
+        return "\n".join(buff + [f"{indent}]"])
+
+    elif hasattr(t, '_fields'):  # namedtuples
+        buff = [f"{type(t).__name__}("]
+        for field, value in zip(t._fields, t):
+            buff.append(f"{indent}  {field}=" + pp(value, indent+"  ")+",")
+        return "\n".join(buff + [f"{indent})"])
+
+    elif isinstance(t, tuple):  # tuples
+        buff = ["("]
+        for e in t:
+            buff.append(f"{indent}  " + pp(e, indent+"  ")+",")
+        return "\n".join(buff + [f"{indent})"])
+
+    else:
+        return repr(t)
+
 parser = argparse.ArgumentParser()
 
 def main():
     """REPL entry point."""
 
     args = parser.parse_args(sys.argv[1:])
-    logger = logging.getLogger("arrdem.datalog")
+    logger = logging.getLogger("flowmetal")
     ch = logging.StreamHandler()
     ch.setLevel(logging.INFO)
     formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
     ch.setFormatter(formatter)
     logger.addHandler(ch)
 
-    session = PromptSession(history=FileHistory(".datalog.history"))
+    session = PromptSession(history=FileHistory(".iflow.history"))
     line_no = 0
 
     while True:
@@ -50,7 +71,7 @@ def main():
             break
 
         try:
-            pprint.pprint(analyzes(line, source_name=f"repl@{line_no}"))
+            print(pp(analyzes(line, source_name=f"repl@{line_no}")))
         except Exception as e:
             print(e)
         finally: