# Buggy code
def __str__(self):
    global _hy_colored_errors

    output = traceback.format_exception_only(SyntaxError, SyntaxError(*self.args))

    if _hy_colored_errors:
        from hy.errors import colored

        output[-1] = colored.yellow(output[-1])
        if len(self.source) > 0:
            output[-2] = colored.green(output[-2])
            for line in output[::-2]:
                if line.strip().startswith('File "{}", line'.format(self.filename)):
                    break
            output[-3] = colored.red(output[-3])

    # Avoid "...expected str instance, ColoredString found"
    return reduce(lambda x, y: x + y, output)


# Traceback (hy.errors.HyCompileError)
Traceback (most recent call last):
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/importer.py", line 180, in hy_eval
_ast, expr = hy_compile(hytree, module_name, get_expr=True)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 2213, in hy_compile
result = compiler.compile(tree)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 460, in compile
ret = self.compile_atom(_type, tree)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 447, in compile_atom
else _compile_table[atom_type](self, atom))
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 1731, in compile_expression
ret = self.compile_atom(fn, expression)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 447, in compile_atom
else _compile_table[atom_type](self, atom))
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 819, in compile_do
return self._compile_branch(expression)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 545, in _compile_branch
return _branch(self.compile(expr) for expr in exprs)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 318, in _branch
results = list(results)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 545, in <genexpr>
return _branch(self.compile(expr) for expr in exprs)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 460, in compile
ret = self.compile_atom(_type, tree)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 447, in compile_atom
else _compile_table[atom_type](self, atom))
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 1731, in compile_expression
ret = self.compile_atom(fn, expression)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 447, in compile_atom
else _compile_table[atom_type](self, atom))
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 372, in checker
return fn(self, expression)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 873, in compile_try_expression
name)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 1002, in _compile_catch_expression
body = self._compile_branch(expr)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 545, in _compile_branch
return _branch(self.compile(expr) for expr in exprs)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 318, in _branch
results = list(results)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 545, in <genexpr>
return _branch(self.compile(expr) for expr in exprs)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 460, in compile
ret = self.compile_atom(_type, tree)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 447, in compile_atom
else _compile_table[atom_type](self, atom))
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 1731, in compile_expression
ret = self.compile_atom(fn, expression)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 447, in compile_atom
else _compile_table[atom_type](self, atom))
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 372, in checker
return fn(self, expression)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 858, in compile_try_expression
body += self.compile(expr.pop(0))
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 472, in compile
raise_empty(HyCompileError, e, sys.exc_info()[2])
File "<string>", line 1, in raise_empty
hy.errors.HyCompileError: Internal Compiler Bug 😱
⤷ ImportError: cannot require names: [HySymbol('let')]
Compilation traceback:
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 460, in compile
ret = self.compile_atom(_type, tree)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 447, in compile_atom
else _compile_table[atom_type](self, atom))
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 1731, in compile_expression
ret = self.compile_atom(fn, expression)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 447, in compile_atom
else _compile_table[atom_type](self, atom))
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/compiler.py", line 1486, in compile_require
require(module, self.module_name, assignments=assignments)
File "/home/johnzhuang/.virtualenvs/hy/lib/python3.6/site-packages/hy/macros.py", line 106, in require
raise ImportError("cannot require names: " + repr(list(unseen)))

# Fixed code
def __str__(self):
    """Provide an exception message that includes SyntaxError-like source
    line information when available.
    """
    global _hy_colored_errors

    # Syntax errors are special and annotate the traceback (instead of what
    # we would do in the message that follows the traceback).
    if isinstance(self, SyntaxError):
        return super(HyLanguageError, self).__str__()

    # When there isn't extra source information, use the normal message.
    if not isinstance(self, SyntaxError) and not self.text:
        return super(HyLanguageError, self).__str__()

    # Re-purpose Python's builtin syntax error formatting.
    output = traceback.format_exception_only(
        SyntaxError,
        SyntaxError(self.msg, (self.filename, self.lineno, self.offset, self.text)),
    )

    arrow_idx, _ = next(
        ((i, x) for i, x in enumerate(output) if x.strip() == "^"), (None, None)
    )
    if arrow_idx:
        msg_idx = arrow_idx + 1
    else:
        msg_idx, _ = next(
            (i, x) for i, x in enumerate(output) if x.startswith("SyntaxError: ")
        )

    # Get rid of erroneous error-type label.
    output[msg_idx] = re.sub("^SyntaxError: ", "", output[msg_idx])

    # Extend the text arrow, when given enough source info.
    if arrow_idx and self.arrow_offset:
        output[arrow_idx] = "{}{}^\n".format(
            output[arrow_idx].rstrip("\n"), "-" * (self.arrow_offset - 1)
        )

    if _hy_colored_errors:
        from clint.textui import colored

        output[msg_idx:] = [colored.yellow(o) for o in output[msg_idx:]]
        if arrow_idx:
            output[arrow_idx] = colored.green(output[arrow_idx])
        for idx, line in enumerate(output[::msg_idx]):
            if line.strip().startswith('File "{}", line'.format(self.filename)):
                output[idx] = colored.red(line)

    # This resulting string will come after a "<class-name>:" prompt, so
    # put it down a line.
    output.insert(0, "\n")

    # Avoid "...expected str instance, ColoredString found"
    return reduce(lambda x, y: x + y, output)