1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
//! Auto-generated module
//!
//! 🤖 Generated with [SplitRS](https://github.com/cool-japan/splitrs)
use crate::lcnf::*;
use std::collections::HashMap;
use super::functions::*;
use super::functions::{FromImports, PYTHON_KEYWORDS};
/// A class variable (field) in a Python class.
#[derive(Debug, Clone, PartialEq)]
pub struct PythonClassVar {
/// Field name
pub name: String,
/// Type annotation
pub annotation: PythonType,
/// Optional default value
pub default: Option<PythonExpr>,
}
/// A Python function definition.
#[derive(Debug, Clone, PartialEq)]
pub struct PythonFunction {
/// Function name
pub name: String,
/// Parameters
pub params: Vec<PythonParam>,
/// Return type annotation
pub return_type: Option<PythonType>,
/// Function body
pub body: Vec<PythonStmt>,
/// Decorator expressions (e.g. `property`, `classmethod`, `staticmethod`)
pub decorators: Vec<String>,
/// Whether this is an async function
pub is_async: bool,
/// Whether this is a classmethod
pub is_classmethod: bool,
/// Whether this is a staticmethod
pub is_staticmethod: bool,
}
impl PythonFunction {
/// Create a new function with just a name, empty body.
pub fn new(name: impl Into<String>) -> Self {
PythonFunction {
name: name.into(),
params: Vec::new(),
return_type: None,
body: Vec::new(),
decorators: Vec::new(),
is_async: false,
is_classmethod: false,
is_staticmethod: false,
}
}
}
/// A Python class definition.
#[derive(Debug, Clone, PartialEq)]
pub struct PythonClass {
/// Class name
pub name: String,
/// Base classes
pub bases: Vec<String>,
/// Methods
pub methods: Vec<PythonFunction>,
/// Class variables / fields (for dataclasses)
pub class_vars: Vec<PythonClassVar>,
/// Whether to annotate with `@dataclass`
pub is_dataclass: bool,
/// Whether to annotate with `ABC` base or `@abstractmethod`
pub is_abstract: bool,
/// Additional decorators
pub decorators: Vec<String>,
/// Docstring
pub docstring: Option<String>,
}
impl PythonClass {
/// Create a new empty class.
pub fn new(name: impl Into<String>) -> Self {
PythonClass {
name: name.into(),
bases: Vec::new(),
methods: Vec::new(),
class_vars: Vec::new(),
is_dataclass: false,
is_abstract: false,
decorators: Vec::new(),
docstring: None,
}
}
}
/// Python function parameter with optional type annotation and default.
#[derive(Debug, Clone, PartialEq)]
pub struct PythonParam {
/// Parameter name
pub name: String,
/// Optional type annotation
pub annotation: Option<PythonType>,
/// Optional default value
pub default: Option<PythonExpr>,
/// Whether this is a `*args` parameter
pub is_vararg: bool,
/// Whether this is a `**kwargs` parameter
pub is_kwarg: bool,
/// Whether this is a keyword-only parameter (after `*`)
pub is_keyword_only: bool,
}
impl PythonParam {
/// Create a simple parameter with just a name.
pub fn simple(name: impl Into<String>) -> Self {
PythonParam {
name: name.into(),
annotation: None,
default: None,
is_vararg: false,
is_kwarg: false,
is_keyword_only: false,
}
}
/// Create a parameter with a type annotation.
pub fn typed(name: impl Into<String>, ty: PythonType) -> Self {
PythonParam {
name: name.into(),
annotation: Some(ty),
default: None,
is_vararg: false,
is_kwarg: false,
is_keyword_only: false,
}
}
}
/// A match case arm: `case <pattern>: <body>`
#[derive(Debug, Clone, PartialEq)]
pub struct MatchArm {
/// The pattern (as raw Python text for flexibility)
pub pattern: String,
/// Optional guard: `if guard`
pub guard: Option<PythonExpr>,
/// Body statements
pub body: Vec<PythonStmt>,
}
/// Python literal value.
#[derive(Debug, Clone, PartialEq)]
pub enum PythonLit {
/// Integer literal: `42`, `-7`
Int(i64),
/// Float literal: `3.14`, `-0.5`
Float(f64),
/// String literal: `"hello"` or `'hello'`
Str(String),
/// Boolean literal: `True` or `False`
Bool(bool),
/// `None` literal
None,
/// Bytes literal: `b"data"`
Bytes(Vec<u8>),
/// Ellipsis: `...`
Ellipsis,
}
/// Python code generation backend.
///
/// Compiles LCNF function declarations to a `PythonModule` containing
/// Python 3.10+ code with type hints.
pub struct PythonBackend {
/// The module being built.
pub module: PythonModule,
/// Mapping from LCNF names to mangled Python names.
pub fn_map: HashMap<String, String>,
/// Counter for generating fresh temporary variable names.
pub fresh_counter: usize,
}
impl PythonBackend {
/// Create a new Python backend.
pub fn new() -> Self {
PythonBackend {
module: PythonModule::new(),
fn_map: HashMap::new(),
fresh_counter: 0,
}
}
/// Generate a fresh temporary variable name: `_t0`, `_t1`, etc.
pub fn fresh_var(&mut self) -> String {
let n = self.fresh_counter;
self.fresh_counter += 1;
format!("_t{}", n)
}
/// Mangle an LCNF name into a valid Python identifier.
///
/// Rules:
/// - Replace `.` with `_`
/// - Replace `'` (prime) with `_prime`
/// - Replace `-` with `_`
/// - Prefix Python reserved words with `_`
pub fn mangle_name(&self, name: &str) -> String {
let mangled: String = name
.chars()
.map(|c| match c {
'.' | '\'' | '-' | ' ' => '_',
c if c.is_alphanumeric() || c == '_' => c,
_ => '_',
})
.collect();
if PYTHON_KEYWORDS.contains(&mangled.as_str())
|| mangled.starts_with(|c: char| c.is_ascii_digit())
{
format!("_{}", mangled)
} else if mangled.is_empty() {
"_anon".to_string()
} else {
mangled
}
}
/// Top-level entry point: compile a slice of LCNF function declarations
/// into a Python module string.
pub fn compile_module(decls: &[LcnfFunDecl]) -> Result<String, String> {
let mut backend = PythonBackend::new();
backend.module.add_from_import(
"typing",
vec![
("Any".to_string(), None),
("Optional".to_string(), None),
("Union".to_string(), None),
("List".to_string(), None),
("Dict".to_string(), None),
("Tuple".to_string(), None),
("Callable".to_string(), None),
],
);
for decl in decls {
let py_name = backend.mangle_name(&decl.name);
backend.fn_map.insert(decl.name.clone(), py_name);
}
for decl in decls {
let func = backend.compile_decl(decl)?;
backend.module.add_function(func);
}
for decl in decls {
if let Some(py_name) = backend.fn_map.get(&decl.name) {
backend.module.all_exports.push(py_name.clone());
}
}
Ok(backend.module.emit())
}
/// Compile a single LCNF function declaration into a `PythonFunction`.
pub fn compile_decl(&mut self, decl: &LcnfFunDecl) -> Result<PythonFunction, String> {
let py_name = self.mangle_name(&decl.name);
let mut func = PythonFunction::new(py_name);
for param in &decl.params {
let param_name = format!("_v{}", param.id.0);
func.params.push(PythonParam {
name: param_name,
annotation: Some(PythonType::Any),
default: None,
is_vararg: false,
is_kwarg: false,
is_keyword_only: false,
});
}
func.return_type = Some(PythonType::Any);
let body_stmts = self.compile_expr_to_stmts(&decl.body)?;
func.body = body_stmts;
Ok(func)
}
/// Compile an LCNF expression into a list of Python statements,
/// ending with a `return`.
pub(super) fn compile_expr_to_stmts(
&mut self,
expr: &LcnfExpr,
) -> Result<Vec<PythonStmt>, String> {
self.compile_expr_stmts_inner(expr, &mut Vec::new())
}
/// Compile an LCNF expression into a sequence of Python statements.
pub(super) fn compile_expr_stmts_inner(
&mut self,
expr: &LcnfExpr,
stmts: &mut Vec<PythonStmt>,
) -> Result<Vec<PythonStmt>, String> {
match expr {
LcnfExpr::Let {
name, value, body, ..
} => {
let py_name = self.mangle_name(name);
let py_val = self.compile_let_value(value)?;
stmts.push(PythonStmt::Assign(vec![PythonExpr::Var(py_name)], py_val));
self.compile_expr_stmts_inner(body, stmts)
}
LcnfExpr::Return(arg) => {
let py_expr = self.compile_arg(arg);
stmts.push(PythonStmt::Return(Some(py_expr)));
Ok(stmts.clone())
}
LcnfExpr::Unreachable => {
stmts.push(PythonStmt::Raise(Some(PythonExpr::Call(
Box::new(PythonExpr::Var("RuntimeError".to_string())),
vec![PythonExpr::Lit(PythonLit::Str("unreachable".to_string()))],
vec![],
))));
Ok(stmts.clone())
}
LcnfExpr::TailCall(func, args) => {
let py_func = self.compile_arg(func);
let py_args: Vec<PythonExpr> = args.iter().map(|a| self.compile_arg(a)).collect();
stmts.push(PythonStmt::Return(Some(PythonExpr::Call(
Box::new(py_func),
py_args,
vec![],
))));
Ok(stmts.clone())
}
LcnfExpr::Case {
scrutinee,
alts,
default,
..
} => {
let scrutinee_name = format!("_v{}", scrutinee.0);
let match_arms: Vec<MatchArm> = alts
.iter()
.map(|alt| {
let pattern = if alt.params.is_empty() {
alt.ctor_name.clone()
} else {
let param_names: Vec<String> =
alt.params.iter().map(|p| format!("_v{}", p.id.0)).collect();
format!("{}({})", alt.ctor_name, param_names.join(", "))
};
let mut arm_stmts = Vec::new();
let _ = self.compile_expr_stmts_inner(&alt.body, &mut arm_stmts);
MatchArm {
pattern,
guard: None,
body: arm_stmts,
}
})
.collect();
let mut all_arms = match_arms;
if let Some(def) = default {
let mut def_stmts = Vec::new();
let _ = self.compile_expr_stmts_inner(def, &mut def_stmts);
all_arms.push(MatchArm {
pattern: "_".to_string(),
guard: None,
body: def_stmts,
});
}
stmts.push(PythonStmt::Match(PythonExpr::Var(scrutinee_name), all_arms));
Ok(stmts.clone())
}
}
}
/// Compile an LCNF argument (atomic value) into a Python expression.
pub(super) fn compile_arg(&self, arg: &LcnfArg) -> PythonExpr {
match arg {
LcnfArg::Var(id) => PythonExpr::Var(format!("_v{}", id.0)),
LcnfArg::Lit(lit) => self.compile_lit(lit),
LcnfArg::Erased => PythonExpr::Lit(PythonLit::None),
LcnfArg::Type(_) => PythonExpr::Lit(PythonLit::None),
}
}
/// Compile an LCNF let-bound value into a Python expression.
pub(super) fn compile_let_value(&mut self, value: &LcnfLetValue) -> Result<PythonExpr, String> {
match value {
LcnfLetValue::App(func, args) => {
let py_func = self.compile_arg(func);
let py_args: Vec<PythonExpr> = args.iter().map(|a| self.compile_arg(a)).collect();
Ok(PythonExpr::Call(Box::new(py_func), py_args, vec![]))
}
LcnfLetValue::Proj(_, idx, var) => {
let obj = PythonExpr::Var(format!("_v{}", var.0));
Ok(PythonExpr::Subscript(
Box::new(obj),
Box::new(PythonExpr::Lit(PythonLit::Int(*idx as i64))),
))
}
LcnfLetValue::Ctor(name, _, args) => {
let py_args: Vec<PythonExpr> = args.iter().map(|a| self.compile_arg(a)).collect();
Ok(PythonExpr::Call(
Box::new(PythonExpr::Var(self.mangle_name(name))),
py_args,
vec![],
))
}
LcnfLetValue::Lit(lit) => Ok(self.compile_lit(lit)),
LcnfLetValue::Erased => Ok(PythonExpr::Lit(PythonLit::None)),
LcnfLetValue::FVar(id) => Ok(PythonExpr::Var(format!("_v{}", id.0))),
LcnfLetValue::Reset(id) => Ok(PythonExpr::Var(format!("_v{}", id.0))),
LcnfLetValue::Reuse(id, name, _, args) => {
let py_args: Vec<PythonExpr> = args.iter().map(|a| self.compile_arg(a)).collect();
let _ = id;
Ok(PythonExpr::Call(
Box::new(PythonExpr::Var(self.mangle_name(name))),
py_args,
vec![],
))
}
}
}
/// Compile an LCNF literal into a Python expression.
pub(super) fn compile_lit(&self, lit: &LcnfLit) -> PythonExpr {
match lit {
LcnfLit::Nat(n) => PythonExpr::Lit(PythonLit::Int(*n as i64)),
LcnfLit::Str(s) => PythonExpr::Lit(PythonLit::Str(s.clone())),
}
}
/// Emit the compiled module as a Python string.
pub fn emit_module(&self) -> String {
self.module.emit()
}
}
/// Python type annotation for type-hinted code generation (PEP 484).
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub enum PythonType {
/// `int`
Int,
/// `float`
Float,
/// `str`
Str,
/// `bool`
Bool,
/// `None`
None_,
/// `list[T]`
List(Box<PythonType>),
/// `dict[K, V]`
Dict(Box<PythonType>, Box<PythonType>),
/// `tuple[T1, T2, ...]`
Tuple(Vec<PythonType>),
/// `T | None` (Optional\[T\])
Optional(Box<PythonType>),
/// `T1 | T2 | ...` (Union)
Union(Vec<PythonType>),
/// User-defined type / class name
Custom(String),
/// `Any` (typing.Any)
Any,
/// `Callable[[A, B], R]`
Callable,
/// `set[T]`
Set(Box<PythonType>),
/// `frozenset[T]`
FrozenSet(Box<PythonType>),
/// `Generator[Y, S, R]`
Generator(Box<PythonType>, Box<PythonType>, Box<PythonType>),
/// `AsyncGenerator[Y, S]`
AsyncGenerator(Box<PythonType>, Box<PythonType>),
/// `Iterator[T]`
Iterator(Box<PythonType>),
/// `Iterable[T]`
Iterable(Box<PythonType>),
/// `Sequence[T]`
Sequence(Box<PythonType>),
/// `Mapping[K, V]`
Mapping(Box<PythonType>, Box<PythonType>),
/// `ClassVar[T]`
ClassVar(Box<PythonType>),
/// `Final[T]`
Final(Box<PythonType>),
/// `type[T]` (the class itself)
Type(Box<PythonType>),
}
/// Part of an f-string.
#[derive(Debug, Clone, PartialEq)]
pub enum FStringPart {
/// Raw string text
Literal(String),
/// Interpolated expression: `{expr}`
Expr(PythonExpr),
/// Interpolated expression with format spec: `{expr:.2f}`
ExprWithFormat(PythonExpr, String),
}
/// Python statement for code generation.
#[derive(Debug, Clone, PartialEq)]
pub enum PythonStmt {
/// Expression statement: `expr`
Expr(PythonExpr),
/// Simple assignment: `target = value`
Assign(Vec<PythonExpr>, PythonExpr),
/// Augmented assignment: `target op= value`
AugAssign(PythonExpr, String, PythonExpr),
/// Annotated assignment: `target: type = value`
AnnAssign(String, PythonType, Option<PythonExpr>),
/// If/elif/else statement
If(
PythonExpr,
Vec<PythonStmt>,
Vec<(PythonExpr, Vec<PythonStmt>)>,
Vec<PythonStmt>,
),
/// For loop: `for var in iter: body`
For(String, PythonExpr, Vec<PythonStmt>, Vec<PythonStmt>),
/// While loop: `while cond: body`
While(PythonExpr, Vec<PythonStmt>, Vec<PythonStmt>),
/// With statement: `with expr as var: body`
With(Vec<(PythonExpr, Option<String>)>, Vec<PythonStmt>),
/// Try/except/else/finally statement
Try(
Vec<PythonStmt>,
Vec<(Option<PythonExpr>, Option<String>, Vec<PythonStmt>)>,
Vec<PythonStmt>,
Vec<PythonStmt>,
),
/// Return statement: `return expr`
Return(Option<PythonExpr>),
/// Raise statement: `raise expr`
Raise(Option<PythonExpr>),
/// Delete statement: `del name`
Del(Vec<PythonExpr>),
/// Pass statement: `pass`
Pass,
/// Break statement: `break`
Break,
/// Continue statement: `continue`
Continue,
/// Import statement: `import module` or `import module as alias`
Import(Vec<(String, Option<String>)>),
/// From-import statement: `from module import name` or `from module import *`
From(String, Vec<(String, Option<String>)>),
/// Class definition
ClassDef(PythonClass),
/// Function definition
FuncDef(PythonFunction),
/// Async function definition
AsyncFuncDef(PythonFunction),
/// Docstring statement
Docstring(String),
/// Assert statement: `assert expr, msg`
Assert(PythonExpr, Option<PythonExpr>),
/// Global declaration: `global x, y`
Global(Vec<String>),
/// Nonlocal declaration: `nonlocal x, y`
Nonlocal(Vec<String>),
/// Match statement (Python 3.10+)
Match(PythonExpr, Vec<MatchArm>),
/// Raw Python text (escape hatch)
Raw(String),
}
/// A complete Python module (one `.py` file).
#[derive(Debug, Clone)]
pub struct PythonModule {
/// Module-level imports: `import X` or `import X as Y`
pub imports: Vec<(String, Option<String>)>,
/// From-imports: `from X import Y` or `from X import Y as Z`
pub from_imports: FromImports,
/// Top-level class definitions
pub classes: Vec<PythonClass>,
/// Top-level function definitions
pub functions: Vec<PythonFunction>,
/// Other top-level statements
pub statements: Vec<PythonStmt>,
/// Module docstring
pub module_docstring: Option<String>,
/// `__all__` exports
pub all_exports: Vec<String>,
}
impl PythonModule {
/// Create a new empty Python module.
pub fn new() -> Self {
PythonModule {
imports: Vec::new(),
from_imports: Vec::new(),
classes: Vec::new(),
functions: Vec::new(),
statements: Vec::new(),
module_docstring: None,
all_exports: Vec::new(),
}
}
/// Add a module-level import.
pub fn add_import(&mut self, module: impl Into<String>, alias: Option<String>) {
self.imports.push((module.into(), alias));
}
/// Add a from-import.
pub fn add_from_import(
&mut self,
module: impl Into<String>,
names: Vec<(String, Option<String>)>,
) {
self.from_imports.push((module.into(), names));
}
/// Add a class definition.
pub fn add_class(&mut self, cls: PythonClass) {
self.classes.push(cls);
}
/// Add a function definition.
pub fn add_function(&mut self, func: PythonFunction) {
self.functions.push(func);
}
/// Add a top-level statement.
pub fn add_statement(&mut self, stmt: PythonStmt) {
self.statements.push(stmt);
}
/// Emit the full Python module as a string.
pub fn emit(&self) -> String {
let mut out = String::new();
if let Some(doc) = &self.module_docstring {
out.push_str(&format!("\"\"\"{}\"\"\"\n\n", doc));
}
let future_imports: Vec<_> = self
.from_imports
.iter()
.filter(|(m, _)| m == "__future__")
.collect();
for (module, names) in &future_imports {
out.push_str(&format_from_import(module, names));
out.push('\n');
}
if !future_imports.is_empty() {
out.push('\n');
}
for (module, alias) in &self.imports {
match alias {
Some(a) => out.push_str(&format!("import {} as {}\n", module, a)),
None => out.push_str(&format!("import {}\n", module)),
}
}
if !self.imports.is_empty() {
out.push('\n');
}
let non_future: Vec<_> = self
.from_imports
.iter()
.filter(|(m, _)| m != "__future__")
.collect();
for (module, names) in &non_future {
out.push_str(&format_from_import(module, names));
out.push('\n');
}
if !non_future.is_empty() {
out.push('\n');
}
if !self.all_exports.is_empty() {
out.push_str("__all__ = [");
for (i, name) in self.all_exports.iter().enumerate() {
if i > 0 {
out.push_str(", ");
}
out.push_str(&format!("\"{}\"", name));
}
out.push_str("]\n\n");
}
for cls in &self.classes {
out.push_str(&emit_class(cls, 0));
out.push_str("\n\n");
}
for func in &self.functions {
out.push_str(&emit_function(func, 0));
out.push_str("\n\n");
}
for stmt in &self.statements {
out.push_str(&emit_stmt(stmt, 0));
out.push('\n');
}
out
}
}
/// Python expression for code generation.
#[derive(Debug, Clone, PartialEq)]
pub enum PythonExpr {
/// A literal value: `42`, `"hello"`, `True`, `None`, etc.
Lit(PythonLit),
/// A variable identifier: `x`, `my_var`
Var(String),
/// Binary operator: `lhs + rhs`, `a == b`, etc.
BinOp(String, Box<PythonExpr>, Box<PythonExpr>),
/// Unary operator: `-x`, `not x`, `~x`
UnaryOp(String, Box<PythonExpr>),
/// Function call: `f(a, b, key=val)`
Call(Box<PythonExpr>, Vec<PythonExpr>, Vec<(String, PythonExpr)>),
/// Attribute access: `obj.field`
Attr(Box<PythonExpr>, String),
/// Subscript: `obj[idx]`
Subscript(Box<PythonExpr>, Box<PythonExpr>),
/// Lambda expression: `lambda x, y: x + y`
Lambda(Vec<String>, Box<PythonExpr>),
/// Conditional (ternary) expression: `a if cond else b`
IfExpr(Box<PythonExpr>, Box<PythonExpr>, Box<PythonExpr>),
/// List comprehension: `[expr for var in iter if cond]`
ListComp(
Box<PythonExpr>,
String,
Box<PythonExpr>,
Option<Box<PythonExpr>>,
),
/// Dict comprehension: `{k: v for k, v in items}`
DictComp(
Box<PythonExpr>,
Box<PythonExpr>,
String,
String,
Box<PythonExpr>,
),
/// Set comprehension: `{x for x in iter}`
SetComp(
Box<PythonExpr>,
String,
Box<PythonExpr>,
Option<Box<PythonExpr>>,
),
/// Generator expression: `(expr for var in iter if cond)`
GenExpr(
Box<PythonExpr>,
String,
Box<PythonExpr>,
Option<Box<PythonExpr>>,
),
/// Tuple literal: `(a, b, c)` or `a, b, c`
Tuple(Vec<PythonExpr>),
/// List literal: `[a, b, c]`
List(Vec<PythonExpr>),
/// Dict literal: `{"key": val, ...}`
Dict(Vec<(PythonExpr, PythonExpr)>),
/// Set literal: `{a, b, c}`
Set(Vec<PythonExpr>),
/// Await expression: `await expr`
Await(Box<PythonExpr>),
/// Yield expression: `yield expr`
Yield(Option<Box<PythonExpr>>),
/// Yield from expression: `yield from expr`
YieldFrom(Box<PythonExpr>),
/// Match expression (Python 3.10+): used as target in match stmt
Match(Box<PythonExpr>),
/// f-string: `f"hello {name}!"`
FString(Vec<FStringPart>),
/// Walrus operator (assignment expression): `name := expr`
Walrus(String, Box<PythonExpr>),
/// Star expression: `*args`
Star(Box<PythonExpr>),
/// Double-star expression: `**kwargs`
DoubleStar(Box<PythonExpr>),
/// Slice: `a:b:c`
Slice(
Option<Box<PythonExpr>>,
Option<Box<PythonExpr>>,
Option<Box<PythonExpr>>,
),
}