Generate more concise syntax and compiler errors

NEWS.rst

@@ -21,6 +21,7 @@ New Features
 
 Bug Fixes
 ------------------------------
+* Cleaned up syntax and compiler errors
 * Fixed issue with empty arguments in `defmain`.
 * `require` now compiles to Python AST.
 * Fixed circular `require`s.

docs/language/cli.rst

@@ -48,12 +48,6 @@ Command Line Options
    `--spy` only works on REPL mode.
    .. versionadded:: 0.9.11
 
-.. cmdoption:: --show-tracebacks
-
-   Print extended tracebacks for Hy exceptions.
-
-   .. versionadded:: 0.9.12
-
 .. cmdoption:: --repl-output-fn
 
    Format REPL output using specific function (e.g., hy.contrib.hy-repr.hy-repr)

hy/__init__.py

@@ -5,6 +5,16 @@
     __version__ = 'unknown'
 
 
+def _initialize_env_var(env_var, default_val):
+    import os, distutils.util
+    try:
+        res = bool(distutils.util.strtobool(
+            os.environ.get(env_var, str(default_val))))
+    except ValueError as e:
+        res = default_val
+    return res
+
+
 from hy.models import HyExpression, HyInteger, HyKeyword, HyComplex, HyString, HyBytes, HySymbol, HyFloat, HyDict, HyList, HySet  # NOQA
 
 

hy/_compat.py

@@ -6,7 +6,7 @@
     import __builtin__ as builtins
 except ImportError:
     import builtins  # NOQA
-import sys, keyword
+import sys, keyword, textwrap
 
 PY3 = sys.version_info[0] >= 3
 PY35 = sys.version_info >= (3, 5)
@@ -22,11 +22,60 @@
 long_type    = int   if PY3 else long         # NOQA
 string_types = str   if PY3 else basestring   # NOQA
 
+#
+# Inspired by the same-named `six` functions.
+#
 if PY3:
-    exec('def raise_empty(t, *args): raise t(*args) from None')
+    raise_src = textwrap.dedent('''
+    def raise_from(value, from_value):
+        raise value from from_value
+    ''')
+
+    def reraise(exc_type, value, traceback=None):
+        try:
+            raise value.with_traceback(traceback)
+        finally:
+            traceback = None
+
+    code_obj_args = ['argcount', 'kwonlyargcount', 'nlocals', 'stacksize',
+                     'flags', 'code', 'consts', 'names', 'varnames',
+                     'filename', 'name', 'firstlineno', 'lnotab', 'freevars',
+                     'cellvars']
 else:
-    def raise_empty(t, *args):
-        raise t(*args)
+    def raise_from(value, from_value=None):
+        raise value
+
+    raise_src = textwrap.dedent('''
+    def reraise(exc_type, value, traceback=None):
+        try:
+            raise exc_type, value, traceback
+        finally:
+            traceback = None
+    ''')
+
+    code_obj_args = ['argcount', 'nlocals', 'stacksize', 'flags', 'code',
+                     'consts', 'names', 'varnames', 'filename', 'name',
+                     'firstlineno', 'lnotab', 'freevars', 'cellvars']
+
+raise_code = compile(raise_src, __file__, 'exec')
+exec(raise_code)
+
+
+def rename_function(func, new_name):
+    """Creates a copy of a function and [re]sets the name at the code-object
+    level.
+    """
+    c = func.__code__
+    new_code = type(c)(*[getattr(c, 'co_{}'.format(a))
+                         if a != 'name' else str(new_name)
+                         for a in code_obj_args])
+
+    _fn = type(func)(new_code, func.__globals__, str(new_name),
+                     func.__defaults__, func.__closure__)
+    _fn.__dict__.update(func.__dict__)
+
+    return _fn
+
 
 def isidentifier(x):
     if x in ('True', 'False', 'None', 'print'):