[P1-HIGH] Lambda/Closure Transpilation Enhancement - 29 Categories Blocked

[noahgift]

Problem Statement

Lambda expressions have 0.783 Tarantula suspiciousness and block 29 corpus categories.

Evidence

From Tarantula Fault Localization:

lambda: 0.783 suspiciousness (4th highest)

Affected Categories (29):

• async_queue, callback_pattern, event_bus, event_emitter, event_observable
• event_saga, event_stream, expression_eval, func_curry, func_either
• func_lens, func_maybe, func_pipeline, functools_ops, generic_container
• generic_iterator, generic_result, generic_visitor, graph_traversal
• graph_unionfind, json_basic, log_parser, lru_cache, and more...

From OIP Historical Analysis:

• Part of ASTTransform category (60.2% of bugs)

Root Cause

Python lambdas don't always map cleanly to Rust closures:

• Capture semantics differ (Python captures by reference, Rust needs explicit)
• Type inference for closure parameters
• Higher-order function compatibility

Files to Modify

• crates/depyler-core/src/rust_gen/expr_gen.rs - Lambda expression codegen
• crates/depyler-core/src/hir.rs - Lambda HIR representation
• crates/depyler-core/src/borrowing_context.rs - Capture analysis

Acceptance Criteria

• Simple lambdas (lambda x: x + 1) transpile correctly
• Lambdas with captures work (lambda x: x + captured_var)
• Higher-order functions with lambdas (map, filter, sorted key=)
• 20+ of 29 blocked categories now compile

Impact: +8-10% single-shot compile rate

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🤖 Generated from OIP/pmat/Tarantula analysis