e588b4928d
* added defmacro! * revert #924 #924 had an error and should never have been merged in the first place. (see #903) * put back import getargspec Without the `formatargspec` this time. * Give better error message on failed macro expansion Better error messages work most of the time. In cases where there are parameters that aren't valid in Python, error message shown is rather ugly. But this is better than no error messages at all and such macros with strange parameter names are rather rare. * fix flake8 errors * Minor English improvements
247 lines
7.7 KiB
Python
247 lines
7.7 KiB
Python
# Copyright (c) 2013 Paul Tagliamonte <paultag@debian.org>
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#
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# Permission is hereby granted, free of charge, to any person obtaining a
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# copy of this software and associated documentation files (the "Software"),
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# to deal in the Software without restriction, including without limitation
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# the rights to use, copy, modify, merge, publish, distribute, sublicense,
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# and/or sell copies of the Software, and to permit persons to whom the
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# Software is furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in
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# all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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# DEALINGS IN THE SOFTWARE.
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from inspect import getargspec, formatargspec
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from hy.models import replace_hy_obj, wrap_value
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from hy.models.expression import HyExpression
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from hy.models.string import HyString
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from hy.errors import HyTypeError, HyMacroExpansionError
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from collections import defaultdict
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CORE_MACROS = [
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"hy.core.bootstrap",
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]
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EXTRA_MACROS = [
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"hy.core.macros",
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]
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_hy_macros = defaultdict(dict)
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_hy_reader = defaultdict(dict)
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def macro(name):
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"""Decorator to define a macro called `name`.
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This stores the macro `name` in the namespace for the module where it is
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defined.
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If the module where it is defined is in `hy.core`, then the macro is stored
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in the default `None` namespace.
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This function is called from the `defmacro` special form in the compiler.
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"""
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def _(fn):
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try:
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argspec = getargspec(fn)
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fn._hy_macro_pass_compiler = argspec.keywords is not None
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except Exception:
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# An exception might be raised if fn has arguments with
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# names that are invalid in Python.
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fn._hy_macro_pass_compiler = False
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module_name = fn.__module__
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if module_name.startswith("hy.core"):
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module_name = None
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_hy_macros[module_name][name] = fn
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return fn
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return _
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def reader(name):
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"""Decorator to define a reader macro called `name`.
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This stores the macro `name` in the namespace for the module where it is
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defined.
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If the module where it is defined is in `hy.core`, then the macro is stored
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in the default `None` namespace.
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This function is called from the `defreader` special form in the compiler.
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"""
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def _(fn):
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module_name = fn.__module__
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if module_name.startswith("hy.core"):
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module_name = None
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_hy_reader[module_name][name] = fn
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return fn
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return _
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def require(source_module, target_module,
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all_macros=False, assignments={}, prefix=""):
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"""Load macros from `source_module` in the namespace of
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`target_module`. `assignments` maps old names to new names, but is
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ignored if `all_macros` is true. If `prefix` is nonempty, it is
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prepended to the name of each imported macro. (This means you get
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macros named things like "mymacromodule.mymacro", which looks like
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an attribute of a module, although it's actually just a symbol
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with a period in its name.)
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This function is called from the `require` special form in the compiler.
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"""
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seen_names = set()
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if prefix:
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prefix += "."
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for d in _hy_macros, _hy_reader:
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for name, macro in d[source_module].items():
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seen_names.add(name)
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if all_macros:
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d[target_module][prefix + name] = macro
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elif name in assignments:
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d[target_module][prefix + assignments[name]] = macro
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if not all_macros:
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unseen = frozenset(assignments.keys()).difference(seen_names)
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if unseen:
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raise ImportError("cannot require names: " + repr(list(unseen)))
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def load_macros(module_name):
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"""Load the hy builtin macros for module `module_name`.
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Modules from `hy.core` can only use the macros from CORE_MACROS.
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Other modules get the macros from CORE_MACROS and EXTRA_MACROS.
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"""
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def _import(module, module_name=module_name):
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"__import__ a module, avoiding recursions"
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if module != module_name:
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__import__(module)
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for module in CORE_MACROS:
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_import(module)
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if module_name.startswith("hy.core"):
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return
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for module in EXTRA_MACROS:
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_import(module)
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def make_empty_fn_copy(fn):
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try:
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# This might fail if fn has parameters with funny names, like o!n. In
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# such a case, we return a generic function that ensures the program
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# can continue running. Unfortunately, the error message that might get
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# raised later on while expanding a macro might not make sense at all.
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argspec = getargspec(fn)
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formatted_args = formatargspec(*argspec)
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fn_str = 'lambda {}: None'.format(
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formatted_args.lstrip('(').rstrip(')'))
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empty_fn = eval(fn_str)
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except Exception:
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def empty_fn(*args, **kwargs):
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None
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return empty_fn
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def macroexpand(tree, compiler):
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"""Expand the toplevel macros for the `tree`.
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Load the macros from the given `module_name`, then expand the (top-level)
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macros in `tree` until it stops changing.
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"""
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load_macros(compiler.module_name)
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old = None
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while old != tree:
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old = tree
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tree = macroexpand_1(tree, compiler)
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return tree
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def macroexpand_1(tree, compiler):
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"""Expand the toplevel macro from `tree` once, in the context of
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`module_name`."""
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if isinstance(tree, HyExpression):
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if tree == []:
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return tree
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fn = tree[0]
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if fn in ("quote", "quasiquote"):
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return tree
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ntree = HyExpression(tree[:])
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ntree.replace(tree)
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opts = {}
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if isinstance(fn, HyString):
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m = _hy_macros[compiler.module_name].get(fn)
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if m is None:
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m = _hy_macros[None].get(fn)
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if m is not None:
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if m._hy_macro_pass_compiler:
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opts['compiler'] = compiler
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try:
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m_copy = make_empty_fn_copy(m)
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m_copy(*ntree[1:], **opts)
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except TypeError as e:
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msg = "expanding `" + str(tree[0]) + "': "
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msg += str(e).replace("<lambda>()", "", 1).strip()
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raise HyMacroExpansionError(tree, msg)
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try:
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obj = wrap_value(m(*ntree[1:], **opts))
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except HyTypeError as e:
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if e.expression is None:
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e.expression = tree
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raise
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except Exception as e:
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msg = "expanding `" + str(tree[0]) + "': " + repr(e)
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raise HyMacroExpansionError(tree, msg)
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replace_hy_obj(obj, tree)
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return obj
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return ntree
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return tree
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def reader_macroexpand(char, tree, compiler):
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"""Expand the reader macro "char" with argument `tree`."""
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load_macros(compiler.module_name)
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reader_macro = _hy_reader[compiler.module_name].get(char)
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if reader_macro is None:
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try:
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reader_macro = _hy_reader[None][char]
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except KeyError:
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raise HyTypeError(
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char,
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"`{0}' is not a defined reader macro.".format(char)
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)
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expr = reader_macro(tree)
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return replace_hy_obj(wrap_value(expr), tree)
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