"""This file contains Hy's core macros that are written in Python and
return compiler Result objects (or Python AST objects) rather than Hy
model trees. These macros serve the role of special forms in other
Lisps: all ordinary macros should eventually compile down to one of
these, or to one of the model builders in hy.compiler."""

# ------------------------------------------------
# * Imports
# ------------------------------------------------

import ast
import textwrap
from contextlib import nullcontext
from itertools import dropwhile

from funcparserlib.parser import finished, forward_decl, many, maybe, oneplus, some

from hy.compat import PY3_11, PY3_12
from hy.compiler import Result, asty, mkexpr
from hy.errors import HyEvalError, HyInternalError, HyTypeError
from hy.macros import pattern_macro, require, require_reader, local_macro_name
from hy.model_patterns import (
    FORM,
    KEYWORD,
    LITERAL,
    STR,
    SYM,
    Tag,
    braces,
    brackets,
    dolike,
    in_tuple,
    keepsym,
    notpexpr,
    parse_if,
    pexpr,
    sym,
    tag,
    times,
    unpack,
)
from hy.models import (
    Bytes,
    Complex,
    Dict,
    Expression,
    FComponent,
    Float,
    FString,
    Integer,
    Keyword,
    List,
    Sequence,
    String,
    Symbol,
    Tuple,
    as_model,
    is_unpack,
)
from hy.reader import mangle
from hy.scoping import OuterVar, ScopeFn, ScopeGen, ScopeLet, is_function_scope, is_inside_function_scope, nearest_python_scope

# ------------------------------------------------
# * Helpers
# ------------------------------------------------

Inf = float("inf")


def pvalue(root, wanted):
    return pexpr(sym(root) + wanted) >> (lambda x: x[0])


def maybe_annotated(target):
    return (
       pexpr(sym("annotate") + target + FORM).named('`annotate` form') |
       (target >> (lambda x: (x, None))))


def dotted(name):
    return Expression(map(Symbol, [".", *name.split(".")]))


type_params = sym(":tp") + brackets(many(
    maybe_annotated(SYM) | unpack("either", Symbol)))

def digest_type_params(compiler, tp):
    "Return a `type_params` attribute for `FunctionDef` etc."

    if tp:
        if not PY3_12:
            compiler._syntax_error(tp, "`:tp` requires Python 3.12 or later")
        tp, = tp
    elif not PY3_12:
        return {}

    return dict(type_params = [
        asty.TypeVarTuple(x[1], name = mangle(x[1]))
            if is_unpack("iterable", x) else
        asty.ParamSpec(x[1], name = mangle(x[1]))
            if is_unpack("mapping", x) else
        asty.TypeVar(x[0],
               name = mangle(x[0]),
               bound = x[1] and compiler.compile(x[1]).force_expr)
        for x in (tp or [])])


# ------------------------------------------------
# * Fundamentals
# ------------------------------------------------


@pattern_macro("do", [many(FORM)])
def compile_do(compiler, expr, root, body):
    return compiler._compile_branch(body)


@pattern_macro(["eval-and-compile", "eval-when-compile", "do-mac"], [many(FORM)])
def compile_eval_foo_compile(compiler, expr, root, body):
    new_expr = Expression([Symbol("do").replace(expr[0])]).replace(expr)

    try:
        value = compiler.eval(new_expr + body)
    except HyInternalError:
        # Unexpected "meta" compilation errors need to be treated
        # like normal (unexpected) compilation errors at this level
        # (or the compilation level preceding this one).
        raise
    except Exception as e:
        # These could be expected Hy language errors (e.g. syntax errors)
        # or regular Python runtime errors that do not signify errors in
        # the compilation *process* (although compilation did technically
        # fail).
        # We wrap these exceptions and pass them through.
        raise HyEvalError(str(e), compiler.filename, body, compiler.source)

    return (
        compiler.compile(as_model(value).replace(expr))
        if root == "do-mac"
        else compiler._compile_branch(body)
        if root == "eval-and-compile"
        else Result()
    )


@pattern_macro(["py", "pys"], [STR])
def compile_inline_python(compiler, expr, root, code):
    exec_mode = root == "pys"

    try:
        o = asty.parse(
            expr,
            textwrap.dedent(code) if exec_mode else "(" + code + "\n)",
            compiler.filename,
            "exec" if exec_mode else "eval",
        ).body
    except (SyntaxError, ValueError) as e:
        raise compiler._syntax_error(
            expr, "Python parse error in '{}': {}".format(root, e)
        )

    return Result(stmts=o) if exec_mode else o


@pattern_macro("pragma", [many(KEYWORD + FORM)])
def compile_pragma(compiler, expr, root, kwargs):
    for kw, value in kwargs:
        if kw == Keyword("warn-on-core-shadow"):
            compiler.local_state_stack[-1]['warn_on_core_shadow'] = (
                bool(compiler.eval(value)))
        else:
            raise compiler._syntax_error(kw, f"Unknown pragma `{kw}`. Perhaps it's implemented by a newer version of Hy.")
    return Result()


# ------------------------------------------------
# * Quoting
# ------------------------------------------------


@pattern_macro(["quote", "quasiquote"], [FORM])
def compile_quote(compiler, expr, root, arg):
    return compiler.compile(render_quoted_form(compiler, arg,
        level = Inf if root == "quote" else 0)[0])
          # Only quasiquotes can unquote

def render_quoted_form(compiler, form, level):
    """
    Render a quoted form as a new hy Expression.

    `level` is the level of quasiquoting of the current form. We can
    unquote if level is 0.

    Returns a two-tuple (`expression`, `splice`).

    The `splice` return value is used to mark `unquote-splice`d forms.
    We need to distinguish them as want to concatenate them instead of
    just nesting them.
    """

    op = None
    if isinstance(form, Expression) and form and isinstance(form[0], Symbol):
        op = mangle(form[0]).replace('_', '-')
        if op in ("unquote", "unquote-splice", "quasiquote"):
            if level == 0 and op != "quasiquote":
                if len(form) != 2:
                    raise HyTypeError(
                        "`%s' needs 1 argument, got %s" % op,
                        len(form) - 1,
                        compiler.filename,
                        form,
                        compiler.source,
                    )
                return form[1], op == "unquote-splice"
            level += 1 if op == "quasiquote" else -1

    name = form.__class__.__name__
    body = [form]

    if isinstance(form, Sequence):
        contents = []
        for x in form:
            f_contents, splice = render_quoted_form(compiler, x, level)
            if splice:
                if is_unpack("iterable", f_contents):
                    raise compiler._syntax_error(f_contents, "`unpack-iterable` is not allowed here")
                f_contents = Expression(
                    [
                        Symbol("unpack-iterable"),
                        Expression([Symbol("or"), f_contents, List()]),
                    ]
                )
            contents.append(f_contents)
        body = [List(contents)]

        if isinstance(form, FString) and form.brackets is not None:
            body.extend([Keyword("brackets"), String(form.brackets)])
        elif isinstance(form, FComponent) and form.conversion is not None:
            body.extend([Keyword("conversion"), String(form.conversion)])

    elif isinstance(form, Symbol):
        body = [String(form), Keyword("from_parser"), Symbol("True")]

    elif isinstance(form, Keyword):
        body = [String(form.name), Keyword("from_parser"), Symbol("True")]

    elif isinstance(form, String):
        if form.brackets is not None:
            body.extend([Keyword("brackets"), String(form.brackets)])

    return (Expression([dotted("hy.models." + name), *body]).replace(form), False)


# ------------------------------------------------
# * Python operators
# ------------------------------------------------


@pattern_macro(["not", "bnot"], [FORM], shadow=True)
def compile_unary_operator(compiler, expr, root, arg):
    ops = {"not": ast.Not, "bnot": ast.Invert}
    operand = compiler.compile(arg)
    return operand + asty.UnaryOp(expr, op=ops[root](), operand=operand.force_expr)


@pattern_macro(["and", "or"], [many(FORM)], shadow=True)
def compile_logical_or_and_and_operator(compiler, expr, operator, args):
    ops = {"and": (ast.And, True), "or": (ast.Or, None)}
    opnode, default = ops[operator]
    if len(args) == 0:
        return asty.Constant(expr[0], value=default)

    ret = None
    var = None          # A temporary variable for assigning results to
    assignment = None   # The current assignment to `var`
    stmts = None        # The current statement list
    can_append = False  # Whether the current expression is the compiled boolop

    def put(node, value):
        # Save the result of the operation so far to `var`.
        nonlocal var, assignment, can_append
        if var is None:
            var = compiler.get_anon_var()
        name = asty.Name(node, id=var, ctx=ast.Store())
        ret.temp_variables.append(name)
        can_append = False
        return (assignment := asty.Assign(node, targets=[name], value=value))

    def get(node):
        # Get the value of `var`, creating it if necessary.
        if var is None:
            stmts.append(put(node, ret.force_expr))
        name = asty.Name(node, id=var, ctx=ast.Load())
        ret.temp_variables.append(name)
        return name

    for value in map(compiler.compile, args):
        if ret is None:
            # This is the first iteration. Don't actually introduce a
            # `BoolOp` yet; the unary case doesn't need it.
            ret = value
            stmts = ret.stmts
            can_append = False
        elif value.stmts:
            # Save the result of the statements to the temporary
            # variable. Use an `if` statement to implement
            # short-circuiting from this point.
            node = value.stmts[0]
            cond = get(node)
            if operator == "or":
                # Negate the conditional.
                cond = asty.UnaryOp(node, op=ast.Not(), operand=cond)
            branch = asty.If(node, test=cond, body=value.stmts, orelse=[])
            stmts.append(branch)
            stmts = branch.body
            stmts.append(put(node, value.force_expr))
        else:
            # Add this value to the current `BoolOp`, or create a new
            # one if we don't have one.
            value = value.force_expr
            def enbool(expr):
                nonlocal can_append
                if can_append:
                    expr.values.append(value)
                    return expr
                can_append = True
                return asty.BoolOp(expr, op=opnode(), values=[expr, value])
            if assignment:
                assignment.value = enbool(assignment.value)
            else:
                ret.expr = enbool(ret.expr)

    if var:
        ret.expr = get(expr)
    return ret


c_ops = {
    "=": ast.Eq,
    "!=": ast.NotEq,
    "<": ast.Lt,
    "<=": ast.LtE,
    ">": ast.Gt,
    ">=": ast.GtE,
    "is": ast.Is,
    "is-not": ast.IsNot,
    "in": ast.In,
    "not-in": ast.NotIn,
}
c_ops = {mangle(k): v for k, v in c_ops.items()}


def get_c_op(compiler, sym):
    k = mangle(sym)
    if k not in c_ops:
        raise compiler._syntax_error(sym, "Illegal comparison operator: " + str(sym))
    return c_ops[k]()


@pattern_macro(["=", "is", "<", "<=", ">", ">="], [oneplus(FORM)], shadow=True)
@pattern_macro(["!=", "is-not", "in", "not-in"], [times(2, Inf, FORM)], shadow=True)
def compile_compare_op_expression(compiler, expr, root, args):
    if len(args) == 1:
        return compiler.compile(args[0]) + asty.Constant(expr, value=True)

    ops = [get_c_op(compiler, root) for _ in args[1:]]
    exprs, ret, _ = compiler._compile_collect(args)
    return ret + asty.Compare(expr, left=exprs[0], ops=ops, comparators=exprs[1:])


@pattern_macro("chainc", [FORM, many(SYM + FORM)])
def compile_chained_comparison(compiler, expr, root, arg1, args):
    ret = compiler.compile(arg1)
    arg1 = ret.force_expr

    ops = [get_c_op(compiler, op) for op, _ in args]
    args, ret2, _ = compiler._compile_collect([x for _, x in args])

    return ret + ret2 + asty.Compare(expr, left=arg1, ops=ops, comparators=args)


# The second element of each tuple below is an aggregation operator
# that's used for augmented assignment with three or more arguments.
m_ops = {
    "+": (ast.Add, "+"),
    "/": (ast.Div, "*"),
    "//": (ast.FloorDiv, "*"),
    "*": (ast.Mult, "*"),
    "-": (ast.Sub, "+"),
    "%": (ast.Mod, None),
    "**": (ast.Pow, "**"),
    "<<": (ast.LShift, "+"),
    ">>": (ast.RShift, "+"),
    "|": (ast.BitOr, "|"),
    "^": (ast.BitXor, None),
    "&": (ast.BitAnd, "&"),
    "@": (ast.MatMult, "@"),
}


@pattern_macro(["+", "*", "|"], [many(FORM)], shadow=True)
@pattern_macro(["-", "/", "&", "@"], [oneplus(FORM)], shadow=True)
@pattern_macro(["**", "//", "<<", ">>"], [times(2, Inf, FORM)], shadow=True)
@pattern_macro(["%", "^"], [times(2, 2, FORM)], shadow=True)
def compile_maths_expression(compiler, expr, root, args):
    if len(args) == 0:
        # Return the identity element for this operator.
        return asty.Constant(expr, value=({"+": 0, "|": 0, "*": 1}[root]))

    if len(args) == 1:
        if root == "/":
            # Compute the reciprocal of the argument.
            args = [Integer(1).replace(expr), args[0]]
        elif root in ("+", "-"):
            # Apply unary plus or unary minus to the argument.
            op = {"+": ast.UAdd, "-": ast.USub}[root]()
            ret = compiler.compile(args[0])
            return ret + asty.UnaryOp(expr, op=op, operand=ret.force_expr)
        else:
            # Return the argument unchanged.
            return compiler.compile(args[0])

    op = m_ops[root][0]
    right_associative = root == "**"
    ret = compiler.compile(args[-1 if right_associative else 0])
    for child in args[-2 if right_associative else 1 :: -1 if right_associative else 1]:
        left_expr = ret.force_expr
        ret += compiler.compile(child)
        right_expr = ret.force_expr
        if right_associative:
            left_expr, right_expr = right_expr, left_expr
        ret += asty.BinOp(expr, left=left_expr, op=op(), right=right_expr)

    return ret


a_ops = {x + "=": v for x, v in m_ops.items()}


@pattern_macro(
    [x for x, (_, v) in a_ops.items() if v is not None], [FORM, oneplus(FORM)]
)
@pattern_macro(
    [x for x, (_, v) in a_ops.items() if v is None], [FORM, times(1, 1, FORM)]
)
def compile_augassign_expression(compiler, expr, root, target, values):
    if len(values) > 1:
        return compiler.compile(
            mkexpr(root, [target], mkexpr(a_ops[root][1], rest=values)).replace(expr)
        )

    op = a_ops[root][0]
    target = compiler._storeize(target, compiler.compile(target))
    ret = compiler.compile(values[0])
    return ret + asty.AugAssign(expr, target=target, value=ret.force_expr, op=op())


# ------------------------------------------------
# * Assignment, mutation, and annotation
# ------------------------------------------------


@pattern_macro("setv", [many(maybe_annotated(FORM) + FORM)])
@pattern_macro("setx", [times(1, 1, SYM + FORM)])
def compile_def_expression(compiler, expr, root, decls):
    if not decls:
        return asty.Constant(expr, value=None)

    result = Result()
    is_assignment_expr = root == "setx"
    for decl in decls:
        if is_assignment_expr:
            ann = None
            name, value = decl
        else:
            (name, ann), value = decl

        result += compile_assign(
            compiler, ann, name, value, is_assignment_expr=is_assignment_expr
        )
    return result


@pattern_macro("let", [brackets(many(maybe_annotated(FORM) + FORM)), many(FORM)])
def compile_let(compiler, expr, root, bindings, body):
    res = Result()
    bindings = bindings[0]
    scope = compiler.scope.create(ScopeLet)

    for (target, ann), value in bindings:
        res += compile_assign(compiler, ann, target, value, let_scope=scope)

    with scope:
        return res + compiler.compile(mkexpr("do", *body).replace(expr))


@pattern_macro(["annotate"], [FORM, FORM])
def compile_basic_annotation(compiler, expr, root, target, ann):
    return compile_assign(compiler, ann, target, None)


def compile_assign(
    compiler, ann, name, value, *, is_assignment_expr=False, let_scope=None
):
    # Ensure that assignment expressions have a result and no annotation.
    assert not is_assignment_expr or (value is not None and ann is None)

    annotate_only = value is None
    if annotate_only:
        result = Result()
    else:
        with let_scope or nullcontext():
            result = compiler.compile(value)
        if let_scope:
            name = let_scope.add(name)

    ld_name = compiler.compile(name)

    if result.temp_variables and isinstance(name, Symbol):
        result.rename(compiler, compiler._nonconst(name))
        if not is_assignment_expr:
            # Throw away .expr to ensure that (setv ...) returns None.
            result.expr = None
    else:
        st_name = compiler._storeize(name, ld_name)

        if ann is not None:
            ann_result = compiler.compile(ann)
            result = ann_result + result

        target = dict(target = st_name)
        if is_assignment_expr:
            node = asty.NamedExpr
        elif ann is not None:
            node = lambda x, **kw: asty.AnnAssign(
                x,
                annotation=ann_result.force_expr,
                simple=int(isinstance(name, Symbol)),
                **kw,
            )
        else:
            node = asty.Assign
            target = dict(targets = [st_name])

        result += node(
            name if hasattr(name, "start_line") else result,
            value=result.force_expr if not annotate_only else None,
            **target
        )

    return result


@pattern_macro(((3, 12), "deftype"), [maybe(type_params), SYM, FORM])
def compile_deftype(compiler, expr, root, tp, name, value):
    return asty.TypeAlias(expr,
       name = asty.Name(name, id = mangle(name), ctx = ast.Store()),
       value = compiler.compile(value).force_expr,
        **digest_type_params(compiler, tp))


@pattern_macro(["global", "nonlocal"], [many(SYM)])
def compile_global_or_nonlocal(compiler, expr, root, syms):
    if not syms:
        return asty.Pass(expr)

    names = [mangle(s) for s in syms]
    if root == "global":
        ret = asty.Global(expr, names=names)
    else:
        ret = OuterVar(expr, compiler.scope, names)

    try:
        compiler.scope.define_nonlocal(ret, root)
    except SyntaxError as e:
        raise compiler._syntax_error(expr, e.msg)

    return ret if syms else Result()


@pattern_macro("del", [many(FORM)])
def compile_del_expression(compiler, expr, name, args):
    if not args:
        return asty.Pass(expr)

    del_targets = []
    ret = Result()
    for target in args:
        compiled_target = compiler.compile(target)
        ret += compiled_target
        del_targets.append(compiler._storeize(target, compiled_target, ast.Del))

    return ret + asty.Delete(expr, targets=del_targets)


# ------------------------------------------------
# * Subsetting
# ------------------------------------------------


@pattern_macro("get", [FORM, oneplus(FORM)], shadow=True)
def compile_index_expression(compiler, expr, name, obj, indices):
    indices, ret, _ = compiler._compile_collect(indices)
    ret += compiler.compile(obj)

    for ix in indices:
        ret += asty.Subscript(
            expr, value=ret.force_expr, slice=ast.Index(value=ix), ctx=ast.Load()
        )

    return ret


notsym = lambda *dissallowed: some(
    lambda x: isinstance(x, Symbol) and str(x) not in dissallowed
)


@pattern_macro(
    ".",
    [
        FORM,
        many(
            SYM
            | brackets(FORM)
            | pexpr(notsym("unpack-iterable", "unpack-mapping"), many(FORM))
        ),
    ],
)
def compile_attribute_access(compiler, expr, name, invocant, keys):
    ret = compiler.compile(invocant)

    for attr in keys:
        if isinstance(attr, Symbol):
            ret += asty.Attribute(
                attr, value=ret.force_expr, attr=mangle(attr), ctx=ast.Load()
            )
        elif isinstance(attr, Expression):
            root, args = attr
            func = asty.Attribute(
                root, value=ret.force_expr, attr=mangle(root), ctx=ast.Load()
            )

            args, funcret, keywords = compiler._compile_collect(args, with_kwargs=True)
            ret += (
                funcret
                + func
                + asty.Call(expr, func=func, args=args, keywords=keywords)
            )
        else:  # attr is a hy List
            compiled_attr = compiler.compile(attr[0])
            ret = (
                compiled_attr
                + ret
                + asty.Subscript(
                    attr,
                    value=ret.force_expr,
                    slice=ast.Index(value=compiled_attr.force_expr),
                    ctx=ast.Load(),
                )
            )

    return ret


@pattern_macro("cut", [FORM, maybe(FORM), maybe(FORM), maybe(FORM)])
def compile_cut_expression(compiler, expr, name, obj, lower, upper, step):
    ret = [Result()]

    def c(e):
        ret[0] += compiler.compile(e)
        return ret[0].force_expr

    if upper is None:
        # cut with single index is an upper bound,
        # this is consistent with slice and islice
        upper = lower
        lower = Symbol("None")

    s = asty.Subscript(
        expr,
        value=c(obj),
        slice=asty.Slice(expr, lower=c(lower), upper=c(upper), step=c(step)),
        ctx=ast.Load(),
    )
    return ret[0] + s


@pattern_macro("unpack-iterable", [FORM])
def compile_unpack_iterable(compiler, expr, root, arg):
    ret = compiler.compile(arg)
    ret += asty.Starred(expr, value=ret.force_expr, ctx=ast.Load())
    return ret


# ------------------------------------------------
# * `if`
# ------------------------------------------------


@pattern_macro("if", [FORM, FORM, FORM])
def compile_if(compiler, expr, _, cond, body, orel_expr):
    cond = compiler.compile(cond)
    body = compiler.compile(body)

    nested = root = False
    orel = Result()
    if (
        isinstance(orel_expr, Expression)
        and isinstance(orel_expr[0], Symbol)
        and orel_expr[0] == Symbol("if*")
    ):
        # Nested ifs: don't waste temporaries
        root = compiler.temp_if is None
        nested = True
        compiler.temp_if = compiler.temp_if or compiler.get_anon_var()
    orel = compiler.compile(orel_expr)

    if not cond.stmts and isinstance(cond.force_expr, ast.Name):
        name = cond.force_expr.id
        branch = None
        if name == "True":
            branch = body
        elif name in ("False", "None"):
            branch = orel
        if branch is not None:
            if compiler.temp_if and branch.stmts:
                name = asty.Name(expr, id=mangle(compiler.temp_if), ctx=ast.Store())

                branch += asty.Assign(expr, targets=[name], value=body.force_expr)

            return branch

    # We want to hoist the statements from the condition
    ret = cond

    if body.stmts or orel.stmts:
        # We have statements in our bodies
        # Get a temporary variable for the result storage
        var = compiler.temp_if or compiler.get_anon_var()
        name = asty.Name(expr, id=mangle(var), ctx=ast.Store())

        # Store the result of the body
        body += asty.Assign(expr, targets=[name], value=body.force_expr)

        # and of the else clause
        if not nested or not orel.stmts or (not root and var != compiler.temp_if):
            orel += asty.Assign(expr, targets=[name], value=orel.force_expr)

        # Then build the if
        ret += asty.If(expr, test=ret.force_expr, body=body.stmts, orelse=orel.stmts)

        # And make our expression context our temp variable
        expr_name = asty.Name(expr, id=mangle(var), ctx=ast.Load())

        ret += Result(expr=expr_name, temp_variables=[expr_name, name])
    else:
        # Just make that an if expression
        ret += asty.IfExp(
            expr, test=ret.force_expr, body=body.force_expr, orelse=orel.force_expr
        )

    if root:
        compiler.temp_if = None

    return ret


# ------------------------------------------------
# * The `for` family
# ------------------------------------------------

loopers = many(
    tag("setv", sym(":setv") + FORM + FORM)
    | tag("if", sym(":if") + FORM)
    | tag("do", sym(":do") + FORM)
    | tag("afor", sym(":async") + FORM + FORM)
    | tag("for", FORM + FORM)
)


@pattern_macro(["for"], [
    brackets(loopers, name = 'square-bracketed loop clauses'),
    many(notpexpr("else")) + maybe(dolike("else"))])
@pattern_macro(["lfor", "sfor", "gfor"], [loopers, FORM])
@pattern_macro(["dfor"], [loopers, finished])
# Here `finished` is a hack replacement for FORM + FORM:
# https://github.com/vlasovskikh/funcparserlib/issues/75
def compile_comprehension(compiler, expr, root, parts, final):
    node_class = {
        "for": asty.For,
        "lfor": asty.ListComp,
        "dfor": asty.DictComp,
        "sfor": asty.SetComp,
        "gfor": asty.GeneratorExp,
    }[root]
    is_for = root == "for"

    ctx = nullcontext() if is_for else compiler.scope.create(ScopeGen)
    mac_con = nullcontext() if is_for else compiler.local_state()
    with mac_con, ctx as scope:

        # Compile the parts.
        if is_for:
            parts = parts[0]
        if node_class is asty.DictComp:
            if not (parts and parts[-1].tag == "for"):
                raise compiler._syntax_error(
                    parts[-1] if parts else parts,
                    "`dfor` must end with key and value forms",
                )
            final = parts.pop().value
        if not parts:
            return Result(
                expr=asty.parse(
                    expr,
                    {
                        asty.For: "None",
                        asty.ListComp: "[]",
                        asty.DictComp: "{}",
                        asty.SetComp: "{1}.__class__()",
                        asty.GeneratorExp: "(_ for _ in [])",
                    }[node_class],
                )
                .body[0]
                .value
            )
        new_parts = []
        for p in parts:
            if p.tag in ("if", "do"):
                tag_value = compiler.compile(p.value)
            else:
                tag_value = [
                    compiler._storeize(p.value[0], compiler.compile(p.value[0])),
                    compiler.compile(p.value[1]),
                ]
                if not is_for:
                    scope.iterator(tag_value[0])
            new_parts.append(Tag(p.tag, tag_value))
        parts = new_parts

        orel = []
        if is_for:
            # Get the `else`.
            body, else_expr = final
            if else_expr is not None:
                orel.append(compiler._compile_branch(else_expr))
                orel[0] += orel[0].expr_as_stmt()
        else:
            # Get the final value (and for dictionary
            # comprehensions, the final key).
            if node_class is asty.DictComp:
                key, elt = map(compiler.compile, final)
            else:
                key = None
                elt = compiler.compile(final)

        # Produce a result.
        if (
            is_for
            or elt.stmts
            or (key is not None and key.stmts)
            or any(
                p.tag == "do"
                or (
                    p.value[1].stmts
                    if p.tag in ("for", "afor", "setv")
                    else p.value.stmts
                )
                for p in parts
            )
        ):
            # The desired comprehension can't be expressed as a
            # real Python comprehension. We'll write it as a nested
            # loop in a function instead.
            def f(parts):
                # This function is called recursively to construct
                # the nested loop.
                if not parts:
                    if is_for:
                        if body:
                            bd = compiler._compile_branch(body)
                            return bd + bd.expr_as_stmt()
                        return Result(stmts=[asty.Pass(expr)])
                    if node_class is asty.DictComp:
                        ret = key + elt
                        val = asty.Tuple(
                            key, ctx=ast.Load(), elts=[key.force_expr, elt.force_expr]
                        )
                    else:
                        ret = elt
                        val = elt.force_expr
                    return ret + asty.Expr(elt, value=asty.Yield(elt, value=val))
                (tagname, v), parts = parts[0], parts[1:]
                if tagname in ("for", "afor"):
                    orelse = orel and orel.pop().stmts
                    node = asty.AsyncFor if tagname == "afor" else asty.For
                    return v[1] + node(
                        v[1],
                        target=v[0],
                        iter=v[1].force_expr,
                        body=f(parts).stmts,
                        orelse=orelse,
                    )
                elif tagname == "setv":
                    return (
                        v[1]
                        + asty.Assign(v[1], targets=[v[0]], value=v[1].force_expr)
                        + f(parts)
                    )
                elif tagname == "if":
                    return v + asty.If(
                        v, test=v.force_expr, body=f(parts).stmts, orelse=[]
                    )
                elif tagname == "do":
                    return v + v.expr_as_stmt() + f(parts)
                else:
                    raise ValueError("can't happen")

            if is_for:
                return f(parts)
            fname = compiler.get_anon_var()
            # Define the generator function.
            stmts = []
            ret = Result()
            assignment_names = scope.finalize()
            if scope.exposing_assignments and assignment_names:
                # expose inner assignments to outer scope
                unlocal_type = (
                    asty.Nonlocal
                    if is_inside_function_scope(scope.parent)
                    else asty.Global
                )
                stmts.append(unlocal_type(expr, names=assignment_names))

                # create a fake assignment statement so python places these
                # names in the immediately outer scope
                if_body = []
                if scope.nonlocal_vars:
                    if_body.append(
                        asty.Nonlocal(expr, names=list(sorted(scope.nonlocal_vars)))
                    )
                assignments = asty.Tuple(
                    expr,
                    elts=[
                        asty.Name(expr, id=var, ctx=ast.Store())
                        for var in assignment_names
                    ],
                    ctx=ast.Store(),
                )
                if_body.append(
                    asty.Assign(
                        expr,
                        targets=[assignments],
                        value=asty.Constant(expr, value=None),
                    )
                )
                ret += asty.If(
                    expr, test=asty.Constant(expr, value=False), body=if_body, orelse=[]
                )

            ret += asty.FunctionDef(
                expr,
                name=fname,
                args=ast.arguments(
                    args=[],
                    vararg=None,
                    kwarg=None,
                    posonlyargs=[],
                    kwonlyargs=[],
                    kw_defaults=[],
                    defaults=[],
                ),
                body=stmts + f(parts).stmts,
                decorator_list=[],
                **({"type_params": []} if PY3_12 else {}),
            )
            # Immediately call the new function. Unless the user asked
            # for a generator, wrap the call in `[].__class__(...)` or
            # `{}.__class__(...)` or `{1}.__class__(...)` to get the
            # right type. We don't want to just use e.g. `list(...)`
            # because the name `list` might be rebound.
            return ret + Result(
                expr=asty.parse(
                    expr,
                    "{}({}())".format(
                        {
                            asty.ListComp: "[].__class__",
                            asty.DictComp: "{}.__class__",
                            asty.SetComp: "{1}.__class__",
                            asty.GeneratorExp: "",
                        }[node_class],
                        fname,
                    ),
                )
                .body[0]
                .value
            )

        # We can produce a real comprehension.
        generators = []
        for tagname, v in parts:
            if tagname in ("for", "afor"):
                generators.append(
                    ast.comprehension(
                        target=v[0],
                        iter=v[1].expr,
                        ifs=[],
                        is_async=int(tagname == "afor"),
                    )
                )
            elif tagname == "setv":
                generators.append(
                    ast.comprehension(
                        target=v[0],
                        iter=asty.Tuple(v[1], elts=[v[1].expr], ctx=ast.Load()),
                        ifs=[],
                        is_async=0,
                    )
                )
            elif tagname == "if":
                generators[-1].ifs.append(v.expr)
            else:
                raise ValueError("can't happen")
        if node_class is asty.DictComp:
            return asty.DictComp(
                expr, key=key.expr, value=elt.expr, generators=generators
            )
        return node_class(expr, elt=elt.expr, generators=generators)


# ------------------------------------------------
# * More looping
# ------------------------------------------------


@pattern_macro(["while"], [FORM, many(notpexpr("else")), maybe(dolike("else"))])
def compile_while_expression(compiler, expr, root, cond, body, else_expr):
    cond_compiled = compiler.compile(cond)

    body = compiler._compile_branch(body)
    body += body.expr_as_stmt()
    body_stmts = body.stmts or [asty.Pass(expr)]

    if cond_compiled.stmts:
        # We need to ensure the statements for the condition are
        # executed on every iteration. Rewrite the loop to use a
        # single anonymous variable as the condition, i.e.:
        #  anon_var = True
        #  while anon_var:
        #    condition stmts...
        #    anon_var = condition expr
        #    if anon_var:
        #      while loop body
        cond_var = asty.Name(cond, id=compiler.get_anon_var(), ctx=ast.Load())

        def make_not(operand):
            return asty.UnaryOp(cond, op=ast.Not(), operand=operand)

        body_stmts = cond_compiled.stmts + [
            asty.Assign(
                cond,
                targets=[compiler._storeize(cond, cond_var)],
                # Cast the condition to a bool in case it's mutable and
                # changes its truth value, but use (not (not ...)) instead of
                # `bool` in case `bool` has been redefined.
                value=make_not(make_not(cond_compiled.force_expr)),
            ),
            asty.If(cond, test=cond_var, body=body_stmts, orelse=[]),
        ]

        cond_compiled = (
            Result()
            + asty.Assign(
                cond,
                targets=[compiler._storeize(cond, cond_var)],
                value=asty.Constant(cond, value=True),
            )
            + cond_var
        )

    orel = Result()
    if else_expr is not None:
        orel = compiler._compile_branch(else_expr)
        orel += orel.expr_as_stmt()

    ret = cond_compiled + asty.While(
        expr, test=cond_compiled.force_expr, body=body_stmts, orelse=orel.stmts
    )

    return ret


@pattern_macro(["break", "continue"], [])
def compile_break_or_continue_expression(compiler, expr, root):
    return (asty.Break if root == "break" else asty.Continue)(expr)


# ------------------------------------------------
# * `with`
# ------------------------------------------------


@pattern_macro("with", [
    brackets(oneplus(maybe(keepsym(":async")) + FORM + FORM)) |
        brackets((maybe(keepsym(":async")) + FORM) >> (lambda x: [(x[0], Symbol("_"), x[1])])),
    many(FORM)])
def compile_with_expression(compiler, expr, root, args, body):

    # We'll store the result of the body in a tempvar
    temp_var = compiler.get_anon_var()
    name = asty.Name(expr, id=mangle(temp_var), ctx=ast.Store())
    # Initialize the tempvar to None in case the `with` exits
    # early with an exception.
    initial_assign = asty.Assign(
        expr, targets=[name], value=asty.Constant(expr, value=None)
    )

    [args] = args
    ret = Result(stmts=[initial_assign])
    items = []
    was_async = None
    cbody = None
    for i, (is_async, variable, ctx) in enumerate(args):
        is_async = bool(is_async)
        if was_async is None:
            was_async = is_async
        elif is_async != was_async:
            # We're compiling a `with` that mixes synchronous and
            # asynchronous context managers. Python doesn't support
            # this directly, so start a new `with` inside the body.
            cbody = compile_with_expression(compiler, expr, root, [args[i:]], body)
            break
        if not isinstance(ctx, Result):
            # In a non-recursive call, `ctx` has not yet been compiled,
            # and thus is not yet a `Result`.
            ctx = compiler.compile(ctx)
            if i == 0:
                ret += ctx
            elif ctx.stmts:
                # We need to include some statements as part of this
                # context manager, but this `with` already has at
                # least one prior context manager. So, put our
                # statements in the body and then start a new `with`.
                cbody = ctx + compile_with_expression(
                    compiler,
                    expr,
                    root,
                    [((is_async, variable, ctx), *args[i + 1:])],
                    body)
                break
        variable = (
            None
            if variable == Symbol("_")
            else compiler._storeize(variable, compiler.compile(variable))
        )
        items.append(
            ast.withitem(context_expr=ctx.force_expr, optional_vars=variable)
        )

    if not cbody:
        cbody = compiler._compile_branch(body)
        cbody += asty.Assign(expr, targets=[name], value=cbody.force_expr)

    node = asty.AsyncWith if was_async else asty.With
    ret += node(expr, body=cbody.stmts, items=items)

    # And make our expression context our temp variable
    expr_name = asty.Name(expr, id=mangle(temp_var), ctx=ast.Load())

    ret += Result(expr=expr_name)
    # We don't give the Result any temp_vars because we don't want
    # Result.rename to touch `name`. Otherwise, initial_assign will
    # clobber any preexisting value of the renamed-to variable.

    return ret


# ------------------------------------------------
# * `match`
# ------------------------------------------------
_pattern = forward_decl()
_pattern.define(
    (
        SYM
        | KEYWORD
        | LITERAL
        | brackets(many(_pattern | unpack("iterable")))
        | in_tuple(many(_pattern | unpack("iterable")))
        | pexpr(keepsym("."), many(SYM))
        | pexpr(keepsym("|"), many(_pattern))
        | braces(many(LITERAL + _pattern), maybe(pvalue("unpack-mapping", SYM)))
        | pexpr(
            pexpr(keepsym("."), oneplus(SYM))
            | notsym(".", "|", "unpack-mapping", "unpack-iterable"),
            many(parse_if(lambda x: not isinstance(x, Keyword), _pattern)),
            many(KEYWORD + _pattern),
        )
    )
    + maybe(sym(":as") + SYM)
)
match_clause = _pattern + maybe(sym(":if") + FORM)


@pattern_macro(((3, 10), "match"), [FORM, many(match_clause + FORM)])
def compile_match_expression(compiler, expr, root, subject, clauses):
    subject = compiler.compile(subject)
    return_var = asty.Name(expr, id=mangle(compiler.get_anon_var()), ctx=ast.Store())

    lifted_if_defs = []
    match_cases = []
    for *pattern, guard, body in clauses:
        if guard and body == Keyword("as"):
            raise compiler._syntax_error(body, ":as clause cannot come after :if guard")

        body = compiler._compile_branch([body])
        body += asty.Assign(pattern[0], targets=[return_var], value=body.force_expr)
        body += body.expr_as_stmt()
        body = body.stmts

        pattern = compile_pattern(compiler, pattern)

        if guard:
            guard = compiler.compile(guard)
            if guard.stmts:
                fname = compiler.get_anon_var()
                guardret = Result() + asty.FunctionDef(
                    guard,
                    name=fname,
                    args=ast.arguments(
                        args=[],
                        kwarg=None,
                        posonlyargs=[],
                        kwonlyargs=[],
                        kw_defaults=[],
                        defaults=[],
                    ),
                    body=guard.stmts + [asty.Return(guard.expr, value=guard.expr)],
                    decorator_list=[],
                    **({"type_params": []} if PY3_12 else {}),
                )
                lifted_if_defs.append(guardret)
                guard = Result(expr=asty.parse(guard, f"{fname}()").body[0].value)

        match_cases.append(
            ast.match_case(
                pattern=pattern,
                guard=guard.force_expr if guard else None,
                body=body,
            )
        )

    returnable = Result(
        expr=asty.Name(expr, id=return_var.id, ctx=ast.Load()),
        temp_variables=[return_var],
    )
    ret = Result() + subject
    ret += asty.Assign(
        expr, targets=[return_var], value=asty.Constant(expr, value=None)
    )
    if not match_cases:
        return ret + returnable

    for lifted_if in lifted_if_defs:
        ret += lifted_if
    ret += asty.Match(expr, subject=subject.force_expr, cases=match_cases)
    return ret + returnable


def compile_pattern(compiler, pattern):
    value, assignment = pattern
    if assignment is not None:
        return compiler.scope.assign(
            asty.MatchAs(
                value,
                pattern=compile_pattern(compiler, (value, None)),
                name=mangle(compiler._nonconst(assignment)),
            )
        )

    if str(value) in ("None", "True", "False"):
        return asty.MatchSingleton(
            value,
            value=compiler.compile(value).force_expr.value,
        )
    elif isinstance(value, (String, Integer, Float, Complex, Bytes)):
        return asty.MatchValue(
            value,
            value=compiler.compile(value).expr,
        )
    elif value == Symbol("_"):
        return asty.MatchAs(value)
    elif isinstance(value, Symbol):
        return compiler.scope.assign(asty.MatchAs(value, name=mangle(value)))
    elif isinstance(value, Expression) and value[0] == Symbol("|"):
        return asty.MatchOr(
            value,
            patterns=[compile_pattern(compiler, v) for v in value[1]],
        )
    elif isinstance(value, Expression) and value[0] == Symbol("."):
        root, syms = value
        dotform = mkexpr(root, *syms).replace(value)
        return asty.MatchValue(
            value,
            value=compiler.compile(dotform).expr,
        )
    elif isinstance(value, (Tuple, List)):
        patterns = value[0]
        patterns = [
            compile_pattern(compiler, (v, None) if is_unpack("iterable", v) else v)
            for v in patterns
        ]
        return asty.MatchSequence(value, patterns=patterns)
    elif is_unpack("iterable", value):
        return compiler.scope.assign(asty.MatchStar(value, name=mangle(value[1])))

    elif isinstance(value, Dict):
        kvs, rest = value
        keys, values = zip(*kvs) if kvs else ([], [])
        # Call `scope.assign` for the assignment to `rest`.
        return compiler.scope.assign(
            asty.MatchMapping(
                value,
                keys=[compiler.compile(key).expr for key in keys],
                patterns=[compile_pattern(compiler, v) for v in values],
                rest=mangle(rest) if rest else None,
            )
        )
    elif isinstance(value, Expression):
        head, args, kwargs = value
        keywords, values = zip(*kwargs) if kwargs else ([], [])
        return asty.MatchClass(
            value,
            cls=compiler.compile(
              # `head` could be a symbol or a dotted form.
                (head[:1] + head[1]).replace(head)
                if type(head) is Expression
                else head).expr,
            patterns=[compile_pattern(compiler, v) for v in args],
            kwd_attrs=[kwd.name for kwd in keywords],
            kwd_patterns=[compile_pattern(compiler, value) for value in values],
        )
    elif isinstance(value, Keyword):
        return asty.MatchClass(
            value,
            cls=compiler.compile(dotted("hy.models.Keyword")).expr,
            patterns=[
                asty.MatchValue(value, value=asty.Constant(value, value=value.name))
            ],
            kwd_attrs=[],
            kwd_patterns=[],
        )
    else:
        raise compiler._syntax_error(value, "unsupported")


# ------------------------------------------------
# * `raise` and `try`
# ------------------------------------------------


@pattern_macro("raise", [maybe(FORM), maybe(sym(":from") + FORM)])
def compile_raise_expression(compiler, expr, root, exc, cause):
    ret = Result()

    if exc is not None:
        exc = compiler.compile(exc)
        ret += exc
        exc = exc.force_expr

    if cause is not None:
        cause = compiler.compile(cause)
        ret += cause
        cause = cause.force_expr

    return ret + asty.Raise(expr, exc=exc, cause=cause)


@pattern_macro(
    "try",
    [
        many(notpexpr("except", "except*", "else", "finally")),
        many(
            pexpr(
                keepsym("except") | keepsym("except*"),
                brackets() | brackets(FORM) | brackets(SYM, FORM),
                many(FORM),
            )
        ),
        maybe(dolike("else")),
        maybe(dolike("finally")),
    ],
)
def compile_try_expression(compiler, expr, root, body, catchers, orelse, finalbody):
    if orelse is not None and not catchers:
        # Python forbids `else` when there are no `except` clauses.
        # But we can get the same effect by appending the `else` forms
        # to the body.
        body += list(orelse)
        orelse = None
    body = compiler._compile_branch(body)
    if not (catchers or finalbody):
        # Python forbids this, so just return the body, per `do`.
        return body

    return_var = asty.Name(expr, id=mangle(compiler.get_anon_var()), ctx=ast.Store())

    handler_results = Result()
    handlers = []
    except_syms_seen = set()
    for catcher in catchers:
        # exceptions catch should be either:
        # [[list of exceptions]]
        # or
        # [variable [list of exceptions]]
        # or
        # [variable exception]
        # or
        # [exception]
        # or
        # []
        except_sym, exceptions, ebody = catcher
        if not PY3_11 and except_sym == Symbol("except*"):
            hy_compiler._syntax_error(except_sym, "`{}` requires Python 3.11 or later")
        except_syms_seen.add(str(except_sym))
        if len(except_syms_seen) > 1:
            raise compiler._syntax_error(
                except_sym, "cannot have both `except` and `except*` on the same `try`"
            )

        name = None
        if len(exceptions) == 2:
            name = mangle(compiler._nonconst(exceptions[0]))

        exceptions_list = exceptions[-1] if exceptions else List()
        if isinstance(exceptions_list, List):
            if len(exceptions_list):
                # [FooBar BarFoo] → catch Foobar and BarFoo exceptions
                elts, types, _ = compiler._compile_collect(exceptions_list)
                types += asty.Tuple(exceptions_list, elts=elts, ctx=ast.Load())
            else:
                # [] → all exceptions caught
                types = Result()
        else:
            types = compiler.compile(exceptions_list)

        # Create a "fake" scope for the exception variable.
        # See: https://docs.python.org/3/reference/compound_stmts.html#the-try-statement
        with compiler.scope.create(ScopeLet) as scope:
            if name:
                scope.add(name, name)
            ebody = compiler._compile_branch(ebody)
        ebody += asty.Assign(catcher, targets=[return_var], value=ebody.force_expr)
        ebody += ebody.expr_as_stmt()

        handler_results += types + asty.ExceptHandler(
            catcher,
            type=types.expr,
            name=name,
            body=ebody.stmts or [asty.Pass(catcher)],
        )
        handlers.append(handler_results.stmts.pop())

    if orelse is None:
        orelse = []
    else:
        orelse = compiler._compile_branch(orelse)
        orelse += asty.Assign(expr, targets=[return_var], value=orelse.force_expr)
        orelse += orelse.expr_as_stmt()
        orelse = orelse.stmts

    if finalbody is None:
        finalbody = []
    else:
        finalbody = compiler._compile_branch(finalbody)
        finalbody += finalbody.expr_as_stmt()
        finalbody = finalbody.stmts

    returnable = Result(
        expr=asty.Name(expr, id=return_var.id, ctx=ast.Load()),
        temp_variables=[return_var],
    )
    body += (
        body.expr_as_stmt()
        if orelse
        else asty.Assign(expr, targets=[return_var], value=body.force_expr)
    )
    body = body.stmts or [asty.Pass(expr)]

    x = (asty.TryStar if "except*" in except_syms_seen else asty.Try)(
        expr, body=body, handlers=handlers, orelse=orelse, finalbody=finalbody
    )
    return handler_results + x + returnable


# ------------------------------------------------
# * Functions and macros
# ------------------------------------------------

NASYM = some(lambda x: isinstance(x, Symbol) and x not in (Symbol("/"), Symbol("*")))
argument = maybe_annotated(NASYM | brackets(NASYM, FORM))
varargs = lambda unpack_type, wanted: maybe_annotated(pvalue(unpack_type, wanted))
kwonly_delim = some(lambda x: x == Symbol("*"))
lambda_list = brackets(
    maybe(many(argument) + sym("/")),
    many(argument),
    maybe(kwonly_delim | varargs("unpack-iterable", NASYM)),
    many(argument),
    maybe(varargs("unpack-mapping", NASYM)),
)


@pattern_macro("fn", [
    maybe(keepsym(":async")),
    maybe(type_params),
    maybe_annotated(lambda_list),
    many(FORM)])
def compile_function_lambda(compiler, expr, root, is_async, tp, params, body):
    params, returns = params
    posonly, args, rest, kwonly, kwargs = params
    has_annotations = returns is not None or any(
        isinstance(param, tuple) and param[1] is not None
        for param in (posonly or []) + args + kwonly + [rest, kwargs]
    )
    args, ret = compile_lambda_list(compiler, params)
    with compiler.local_state(), compiler.scope.create(ScopeFn, args, is_async) as scope:
        body = compiler._compile_branch(body)

    # Compile to lambda if we can
    if not (has_annotations or tp or body.stmts or is_async):
        return ret + asty.Lambda(expr, args=args, body=body.force_expr)

    # Otherwise create a standard function
    node = asty.AsyncFunctionDef if is_async else asty.FunctionDef
    name = compiler.get_anon_var()
    ret += compile_function_node(
        compiler, expr, node, [], tp, name, args, returns, body, scope
    )

    # return its name as the final expr
    return ret + Result(expr=ret.temp_variables[0])


@pattern_macro("defn", [
    maybe(keepsym(":async")),
    maybe(brackets(many(FORM))),
    maybe(type_params),
    maybe_annotated(SYM),
    lambda_list,
    many(FORM)])
def compile_function_def(compiler, expr, root, is_async, decorators, tp, name, params, body):
    name, returns = name
    node = asty.AsyncFunctionDef if is_async else asty.FunctionDef
    decorators, ret, _ = compiler._compile_collect(decorators[0] if decorators else [])
    args, ret2 = compile_lambda_list(compiler, params)
    ret += ret2
    name = mangle(compiler._nonconst(name))
    compiler.scope.define(name)
    with compiler.local_state(), compiler.scope.create(ScopeFn, args, is_async) as scope:
        body = compiler._compile_branch(body)

    return ret + compile_function_node(
        compiler, expr, node, decorators, tp, name, args, returns, body, scope
    )


def compile_function_node(compiler, expr, node, decorators, tp, name, args, returns, body, scope):
    ret = Result()

    if body.expr:
        # implicitly return final expression,
        # except for async generators
        enode = asty.Expr if scope.is_async and scope.has_yield else asty.Return
        body += enode(body.expr, value=body.expr)

    ret += node(
        expr,
        name=name,
        args=args,
        body=body.stmts or [asty.Pass(expr)],
        decorator_list=decorators,
        returns=compiler.compile(returns).force_expr if returns is not None else None,
        **digest_type_params(compiler, tp),
    )

    ast_name = asty.Name(expr, id=name, ctx=ast.Load())
    return ret + Result(temp_variables=[ast_name, ret.stmts[-1]])


@pattern_macro(
    "defmacro",
    [
        SYM,
        brackets(
            maybe(many(argument) + sym("/")),
            many(argument),
            maybe(varargs("unpack-iterable", NASYM)),
        ),
        many(FORM),
    ],
)
def compile_macro_def(compiler, expr, root, name, params, body):
    def E(*x): return Expression(x)
    S = Symbol

    compiler.warn_on_core_shadow(name)
    fn_def = E(S("fn"), List(expr[2]), *body).replace(expr)
    if compiler.is_in_local_state():
        # We're in a local scope, so define the new macro locally.
        state = compiler.local_state_stack[-1]
        # Produce code that will set the macro to a local variable.
        ret = compiler.compile(E(
            S("setv"),
            S(local_macro_name(name)),
            fn_def).replace(expr))
        # Also evaluate the macro definition now, and put it in
        # state['macros'].
        state['macros'][mangle(name)] = compiler.eval(fn_def)
        return ret + ret.expr_as_stmt()
    # Otherwise, define the macro module-wide.
    ret = compiler.compile(E(S("eval-and-compile"), E(
        E(dotted("hy.macros.macro"), str(name)),
        fn_def)).replace(expr))
    return ret + ret.expr_as_stmt()


def compile_lambda_list(compiler, params):
    ret = Result()
    posonly_parms, args_parms, rest_parms, kwonly_parms, kwargs_parms = params

    if not (posonly_parms or posonly_parms is None):
        raise compiler._syntax_error(
            params, "at least one argument must precede /"
        )

    posonly_parms = posonly_parms or []

    is_positional_arg = lambda x: isinstance(x[0], Symbol)
    invalid_non_default = next(
        (
            arg
            for arg in dropwhile(is_positional_arg, posonly_parms + args_parms)
            if is_positional_arg(arg)
        ),
        None,
    )
    if invalid_non_default:
        raise compiler._syntax_error(
            invalid_non_default[0], "non-default argument follows default argument"
        )

    posonly_ast, posonly_defaults, ret = compile_arguments_set(
        compiler, posonly_parms, ret
    )
    args_ast, args_defaults, ret = compile_arguments_set(compiler, args_parms, ret)
    kwonly_ast, kwonly_defaults, ret = compile_arguments_set(
        compiler, kwonly_parms, ret, True
    )
    rest_ast = kwargs_ast = None

    if rest_parms == Symbol("*"):  # rest is a positional only marker
        if not kwonly_parms:
            raise compiler._syntax_error(
                rest_parms, "named arguments must follow bare *"
            )
        rest_ast = None
    elif rest_parms:  # rest is capturing varargs
        [rest_ast], _, ret = compile_arguments_set(compiler, [rest_parms], ret)
    if kwargs_parms:
        [kwargs_ast], _, ret = compile_arguments_set(compiler, [kwargs_parms], ret)

    return (
        ast.arguments(
            args=args_ast,
            defaults=[*posonly_defaults, *args_defaults],
            vararg=rest_ast,
            posonlyargs=posonly_ast,
            kwonlyargs=kwonly_ast,
            kw_defaults=kwonly_defaults,
            kwarg=kwargs_ast,
        ),
        ret,
    )


def compile_arguments_set(compiler, decls, ret, is_kwonly=False):
    args_ast = []
    args_defaults = []

    for decl, ann in decls:
        default = None

        # funcparserlib will check to make sure that the only times we
        # ever have a hy List here are due to a default value.
        if isinstance(decl, List):
            sym, default = decl
        else:
            sym = decl

        if ann is not None:
            ret += compiler.compile(ann)
            ann_ast = ret.force_expr
        else:
            ann_ast = None

        if default is not None:
            ret += compiler.compile(default)
            args_defaults.append(ret.force_expr)
        # Kwonly args without defaults are considered required
        elif not isinstance(decl, List) and is_kwonly:
            args_defaults.append(None)
        elif isinstance(decl, List):
            # Note that the only time any None should ever appear here
            # is in kwargs, since the order of those with defaults vs
            # those without isn't significant in the same way as
            # positional args.
            args_defaults.append(None)

        args_ast.append(
            asty.arg(sym, arg=mangle(compiler._nonconst(sym)), annotation=ann_ast)
        )

    return args_ast, args_defaults, ret


@pattern_macro("return", [maybe(FORM)])
def compile_return(compiler, expr, root, arg):
    ret = Result()
    if arg is None:
        return asty.Return(expr, value=None)
    ret += compiler.compile(arg)
    return ret + asty.Return(expr, value=ret.force_expr)


@pattern_macro("yield", [times(0, 2, FORM)])
def compile_yield_expression(compiler, expr, root, args):
    if is_inside_function_scope(compiler.scope):
        nearest_python_scope(compiler.scope).has_yield = True
    yield_from = False
    if len(args) == 2:
        from_kw, x = args
        if from_kw != Keyword("from"):
            raise compiler._syntax_error(from_kw, "two-argument `yield` requires `:from`")
        yield_from = True
        args = [x]
    ret = Result()
    if args:
        ret += compiler.compile(args[0])
    return ret + (asty.YieldFrom if yield_from else asty.Yield)(expr, value=ret.force_expr)


@pattern_macro("await", [FORM])
def compile_yield_from_or_await_expression(compiler, expr, root, arg):
    ret = Result() + compiler.compile(arg)
    return ret + asty.Await(expr, value=ret.force_expr)


# ------------------------------------------------
# * `defclass`
# ------------------------------------------------


@pattern_macro(
    "defclass",
    [
        maybe(brackets(many(FORM))),
        maybe(type_params),
        SYM,
        maybe(brackets(many(FORM)) + maybe(STR) + many(FORM)),
    ],
)
def compile_class_expression(compiler, expr, root, decorators, tp, name, rest):
    base_list, docstring, body = rest or ([[]], None, [])

    decorators, ret, _ = compiler._compile_collect(decorators[0] if decorators else [])
    bases_expr, ret2, keywords = compiler._compile_collect(
        base_list[0], with_kwargs=True
    )
    ret += ret2

    bodyr = Result()

    if docstring is not None:
        bodyr += compiler.compile(docstring).expr_as_stmt()

    name = mangle(compiler._nonconst(name))
    compiler.scope.define(name)

    with compiler.local_state(), compiler.scope.create(ScopeFn):
        e = compiler._compile_branch(body)
        bodyr += e + e.expr_as_stmt()

    return ret + asty.ClassDef(
        expr,
        decorator_list=decorators,
        name=name,
        keywords=keywords,
        bases=bases_expr,
        body=bodyr.stmts or [asty.Pass(expr)],
        **digest_type_params(compiler, tp)
    )


# ------------------------------------------------
# * `import` and `require`
# ------------------------------------------------

module_name_pattern = SYM | pexpr(
    some(lambda x: isinstance(x, Symbol) and not str(x[0]).strip(".")) + oneplus(SYM)
)


def module_name_str(x):
    return (
        ".".join(map(mangle, x[1][x[1][0] == Symbol("None") :]))
        if isinstance(x, Expression)
        else str(x)
        if isinstance(x, Symbol) and not x.strip(".")
        else mangle(x)
    )


importlike = (
    keepsym("*")
    | (keepsym(":as") + SYM)
    | brackets(many(SYM + maybe(sym(":as") + SYM)))
)


def assignment_shape(module, rest):
    prefix = ""
    assignments = "EXPORTS"
    if rest is None:
        # (import foo)
        prefix = module_name_str(module)
    elif rest == Symbol("*"):
        # (import foo *)
        pass
    elif rest[0] == Keyword("as"):
        # (import foo :as bar)
        prefix = mangle(rest[1])
    else:
        # (import foo [bar baz :as MyBaz bing])
        assignments = [(k, v or k) for k, v in rest[0]]
    return prefix, assignments


@pattern_macro(
    "require",
    [
        many(
            module_name_pattern
            + times(
                0,
                2,
                (maybe(sym(":macros")) + importlike)
                | (keepsym(":readers") + (keepsym("*") | brackets(many(SYM)))),
            )
        )
    ],
)
def compile_require(compiler, expr, root, entries):
    ret = Result()
    for entry in entries:
        module, assignments = entry
        readers, rest = (
            [names for key, names in assignments if (key == Keyword("readers")) == flag]
            for flag in (True, False)
        )
        if len(rest) > 1 or len(readers) > 1:
            raise compiler._syntax_error(
                entry,
                f"redefinition of ':{'macros' if len(rest) > 1 else 'readers'}' brackets.",
            )

        rest = rest[0] if rest else None  # None used for prefixed macro import
        readers = readers and readers[0]

        prefix, assignments = assignment_shape(module, rest)
        module_name = module_name_str(module)
        if isinstance(module, Expression) and module[1][0] == Symbol("None"):
            # Prepend leading dots to `module_name`.
            module_name = str(module[0]) + module_name

        # we don't want to import all macros as prefixed if we're specifically
        # importing readers but not macros
        # (require a-module :readers ["!"])
        if (rest or not readers) and compiler.is_in_local_state():
            reqs = require(
                module_name,
                compiler.local_state_stack[-1]['macros'],
                assignments = assignments,
                prefix = prefix,
                compiler = compiler)
            ret += compiler.compile(Expression([
                Symbol("setv"),
                List([Symbol(local_macro_name(m)) for m, _, _ in reqs]),
                Expression([
                    dotted("hy.macros.require_vals"),
                    String(module_name),
                    Dict(),
                    Keyword("assignments"),
                    List([(String(m), String(m)) for _, m, _ in reqs])])]).replace(expr))
            ret += ret.expr_as_stmt()
        elif (rest or not readers) and require(
                module_name,
                compiler.module,
                assignments = assignments,
                prefix = prefix,
                compiler = compiler):
            # Actually calling `require` is necessary for macro expansions
            # occurring during compilation.
            # The `require` we're creating in AST is the same as above, but used at
            # run-time (e.g. when modules are loaded via bytecode).
            ret += compiler.compile(
                Expression(
                    [
                        dotted("hy.macros.require"),
                        String(module_name),
                        Symbol("None"),
                        Keyword("target_module_name"),
                        String(compiler.module.__name__),
                        Keyword("assignments"),
                        (
                            String("EXPORTS")
                            if assignments == "EXPORTS"
                            else List([List([String(k), String(v)]) for k, v in assignments])
                        ),
                        Keyword("prefix"),
                        String(prefix),
                    ]
                ).replace(expr)
            )
            ret += ret.expr_as_stmt()

        if readers:
            reader_assignments = (
                "ALL"
                if readers == Symbol("*")
                else [str(reader) for reader in readers[0]]
            )
            if require_reader(module_name, compiler.module, reader_assignments):
                ret += compiler.compile(
                    mkexpr(
                        "do",
                        mkexpr(
                            dotted("hy.macros.require-reader"),
                            String(module_name),
                            "None",
                            [reader_assignments],
                        ),
                        mkexpr(
                            "eval-when-compile",
                            mkexpr(
                                dotted("hy.macros.enable-readers"),
                                "None",
                                mkexpr(dotted("hy.reader.HyReader.current-reader")),
                                [reader_assignments],
                            ),
                        ),
                    ).replace(expr)
                )
                ret += ret.expr_as_stmt()
    return ret


@pattern_macro("import", [many(module_name_pattern + maybe(importlike))])
def compile_import(compiler, expr, root, entries):
    ret = Result()

    for entry in entries:
        module, _ = entry
        prefix, assignments = assignment_shape(*entry)
        module_name = module_name_str(module)
        if assignments == "EXPORTS" and prefix == "":
            node = asty.ImportFrom
            names = [asty.alias(module, name="*", asname=None)]
        elif assignments == "EXPORTS":
            compiler.scope.define(prefix)
            node = asty.Import
            names = [asty.alias(
                module,
                name = module_name,
                asname = prefix if prefix != module_name else None)]
        else:
            node = asty.ImportFrom
            names = []
            for k, v in assignments:
                compiler.scope.define(mangle(v))
                names.append(asty.alias(
                    module,
                    name = mangle(k),
                    asname = None if v == k else mangle(v)))
        ret += node(
            expr,
            names = names,
            **({} if node is asty.Import else dict(
                module = module_name
                    if module_name and module_name.strip(".")
                    else None,
                level =
                    len(module[0])
                    if isinstance(module, Expression)
                        and module[1][0] == Symbol("None")
                    else len(module)
                    if isinstance(module, Symbol)
                        and not module.strip(".")
                    else 0)))

    return ret


# ------------------------------------------------
# * Miscellany
# ------------------------------------------------


@pattern_macro("assert", [FORM, maybe(FORM)])
def compile_assert_expression(compiler, expr, root, test, msg):
    test = compiler.compile(test)
    if msg:
        msg = compiler.compile(msg)

    if not (test.stmts or (msg and msg.stmts)):
        return asty.Assert(expr, test=test.force_expr, msg=msg and msg.force_expr)

    return asty.If(
        expr,
        test=asty.Name(expr, id="__debug__", ctx=ast.Load()),
        orelse=[],
        body=test.stmts
        + [
            asty.If(
                test,
                test=asty.UnaryOp(test, op=ast.Not(), operand=test.force_expr),
                orelse=[],
                body=(msg.stmts if msg else [])
                + [
                    asty.Assert(
                        expr,
                        test=asty.Constant(test, value=False),
                        msg=msg and msg.force_expr,
                    )
                ],
            )
        ],
    )


@pattern_macro(
    "unquote unquote-splice unpack-mapping except except* finally else".split(),
    [many(FORM)],
)
def compile_placeholder(compiler, expr, root, body):
    raise ValueError(f"`{root}` is not allowed here")
