feat: add lambda expression support to BAML compiler by hellovai · Pull Request #3302 · BoundaryML/baml

hellovai · 2026-03-29T10:53:12Z

What problems was I solving

BAML had no support for lambda expressions (anonymous functions / closures). Users couldn't write inline callbacks, pass functions to higher-order methods like .map(), or use closures that capture variables from enclosing scopes. Every transformation required a named function definition, making code verbose and blocking a broad class of functional programming patterns — from simple transforms to closures returned from functions, IIFEs, and nested lambdas with shared mutable state.

After this PR, lambda expressions are a first-class feature across the entire compiler stack: they parse, format, type-check with bidirectional inference, compile to bytecode with cell-based capture semantics, and execute in the VM with full GC support. Users can write lambdas with minimal annotation — parameter and return types are inferred from context when possible.

What user-facing changes did I ship

Lambda expression syntax: (params) -> [RetType] { body } with optional type annotations, optional return type, optional generic parameters (<T>(x: T) -> T { x }), and optional throws clauses
Bidirectional type inference: lambda parameter types inferred from call context (e.g. items.map((x) -> { x * 2 }) infers x: int from Array<int>.map)
Closure capture semantics: lambdas capture variables by shared reference via cells — mutations in the closure are visible to the parent and vice versa
Transitive capture propagation: nested lambdas automatically capture variables from grandparent+ scopes through intermediate lambdas
New container methods: Array.map, Map.map, Map.map_keys, Map.map_values — higher-order methods that accept lambda callbacks
Error diagnostics: type mismatches, arity mismatches, missing param annotations (when no context available), and param type conflicts are all reported
Test projects: lambda_basic (9 functions), lambda_advanced (~33 functions), lambda_errors (4 error cases) with full snapshot coverage across all 8 compiler phases

How I implemented it

This was a full-stack feature spanning every compiler layer, implemented across 18 commits in two tasks: first the frontend (parser → AST → HIR → TIR + formatter), then the backend (MIR → emit → bytecode → VM → GC).

1. Syntax & Parser

syntax_kind.rs — Added LAMBDA_EXPR node kind to the CST
parser.rs — Added looks_like_lambda() and looks_like_generic_lambda() disambiguation predicates with depth-aware paren scanning (up to 64 tokens lookahead). Added parse_lambda_expr() with parse_lambda_parameter_list() (optional type annotations unlike regular function params). Hooked into parse_primary_expr for both LParen (regular lambdas) and Less (generic lambdas)

2. AST Lowering

ast.rs — Added Expr::Lambda(Box<FunctionDef>) variant reusing the existing FunctionDef struct with synthetic name "<anonymous function>"
lower_expr_body.rs — Added lower_lambda_expr with a fresh LoweringContext for the lambda's own ExprBody arena. Made lower_params public via lower_cst.rs

3. HIR Scope Registration & Capture Analysis

hir/builder.rs — Added pass that pushes ScopeKind::Lambda, registers params, and recursively walks the lambda's own ExprBody. ScopeBindings.captures records which parent-scope variables each lambda references. ScopeBindings.captured_names on function scopes marks which locals are captured by any descendant lambda — the foundation for cell wrapping in MIR

4. TIR Type Inference

tir/builder.rs — Three major additions:
1. infer_expr (synthesis): Lambda with no expected type — requires annotated params, infers return from body
2. check_expr (checking): Lambda with expected Ty::Function — decomposes expected type for bidirectional param/return inference (the key to items.map((x) -> { x * 2 }))
3. infer_lambda_body helper: Save/restore approach for locals, declared_types, return_ty, generic_params, and expressions (to prevent ExprId collisions between lambda and parent arenas). Lambda params seeded on top of parent locals so captures work naturally
4. Two-pass generic call inference: Non-lambda args are inferred first to bind type vars, then lambda args are checked with resolved bindings (e.g. apply((x) -> { x * 2 }, 21) binds T=int from 21 before checking the lambda)
5. Method-level generic resolution: Fixed resolve_member_access to include method-level generics in bindings so items.map(...) resolves correctly
infer_context.rs — Added CannotInferLambdaParamType diagnostic variant
normalize.rs — Fixed Optional/Union subtyping to work in both directions

5. Formatter

expressions.rs — Added LambdaExpr, GenericParamList, ThrowsClause structs with full FromCST/Printable impls, dispatching on LAMBDA_EXPR CST node
tokens.rs / lib.rs — Supporting token and top-level dispatch additions

6. Container Builtins

containers.baml — Added Array.map(self, f: (T) -> U) -> U[], Map.map(self, f: (K, V) -> U) -> U[], Map.map_keys, Map.map_values
array.rs / map.rs — VM implementations that invoke closures via call_indirect

7. VM Structural Foundation

types.rs — Object::Closure { function: HeapPtr, captures: Vec<Value> } and Object::Cell { value: Value } with full Display, ObjectType, and value_type_tag support
bytecode.rs — 7 new instructions: MakeClosure, MakeCell, LoadDeref, StoreDeref, LoadCapture, StoreCapture, and CaptureRef (7th not in original plan — needed for forwarding cell pointers to inner closures)
gc.rs — add_references_to_worklist and fixup_object_references trace Closure/Cell objects
vm.rs — collect_frame_roots and apply_frame_forwarding ensure frame function pointers survive GC relocation. Execution handlers for all 7 instructions. resolve_callable_target, load_function, execute_call_from_locals_offset, and allocate_real_locals_for_frame all extended for Object::Closure
lib.rs (engine) — Frame root collection and forwarding in GC cycle

8. MIR IR & Lowering

ir.rs — Rvalue::MakeClosure { lambda_idx, captures }, Place::Capture(idx), MirFunction.lambdas: Vec<MirFunction>, LocalDecl.is_captured: bool
lower.rs — Key migration: expr_types key changed from AstExprId to (FileScopeId, AstExprId) with current_scope tracking, eliminating ExprId collisions. Added lower_lambda method with full save/restore of parent state (builder, body, source_map, locals, exit_block, loop/catch context, pending_lambdas, capture_indices). HIR captured_names → is_captured flag. capture_indices: Option<HashMap<Name, usize>> for lambda body variable resolution. transitive_captures_needed: Vec<Name> for nested lambda propagation

9. Emit Layer

pull_semantics.rs — make_closure(), load_capture(), store_capture_value() trait methods + walk_rvalue_pull and walk_place_pull arms
emit.rs — lambda_object_indices, lambda_names, captured_locals, loading_for_closure_capture fields on StackifyCodegen. Cell-wrapping preamble: LoadVar → MakeCell → StoreVar for each is_captured local. Parent-side deref: LoadDeref/StoreDeref instead of LoadVar/StoreVar. Capture operand loading: LoadVar (bypassing deref) when loading_for_closure_capture is set. Lambda body: Place::Capture(idx) → LoadCapture(idx) / StoreCapture(idx). Transitive forwarding: CaptureRef(idx) via load_capture when loading_for_closure_capture is set
lib.rs (emit) — compile_lambdas_flat() recursively compiles lambda MirFunctions into bytecode Function objects, registering them in program.objects. lower_let_body changed to return lambdas alongside the body

10. Tests

compiler2_tir/mod.rs — 216+ lines of TIR snapshot infrastructure: format_lambda_signature, render_expr_body_untyped, lambda capture annotations, compound argument expansion
52+ new snapshot files across lexer, parser, HIR, TIR, MIR, diagnostics, codegen, and formatter phases for all three lambda test projects
Existing snapshot updates — Minor codegen snapshot changes in 8 existing test projects (format_checks, control_flow, etc.) due to new container methods

Deviations from the plans

This feature was implemented across two plans:

Plan A ("Lambda Expression Support"): parser → AST → HIR → TIR + formatter
Plan B ("Lambda Closure Compilation and Runtime Support"): MIR → emit → VM → GC

Implemented as planned

Plan A: Test projects, parser with disambiguation, Expr::Lambda(Box<FunctionDef>), HIR lambda scope pass, formatter LambdaExpr — all match plan
Plan B: Phase 1 structural foundation (VM types, GC, bytecode, MIR IR), Phase 2 ExprId fix + emit infrastructure, Phase 3 non-capturing lambda lowering, Phase 4 capturing lambdas with cells, Phase 5 transitive captures — all match plan

Deviations/surprises

Save/restore vs nested builder (Plan A): Plan A discussed both approaches and preferred nested builder for TIR. Implementation used the simpler save/restore approach, noting ExprId collisions as fixable (and Plan B fixed them via the (FileScopeId, AstExprId) key migration)
Two-pass call inference (Plan A): Plan A specified a single-pass with contains_typevar check. Implementation went further with a true two-pass approach (non-lambda args first, then lambda args) for better generic resolution
Method-level generics fix (Plan A): Plan A said resolve_member_access needed "no changes." Implementation found and fixed a bug where method-level generic params (like  on Array.map) weren't being added to bindings
Optional/Union subtyping fix (Plan A): Plan A said normalize.rs needed "no changes." A bug was found and fixed where Optional<T> wasn't recognized as a subtype of Union types containing T and Null
7th bytecode instruction CaptureRef (Plan B): Plan B specified 6 instructions. Implementation added a 7th — CaptureRef pushes the raw cell pointer from a closure's captures without reading through the cell. Necessary for forwarding captured cells to inner closures during transitive capture propagation
loading_for_closure_capture flag (Plan B): Emit layer uses a boolean on StackifyCodegen to distinguish "load for closure capture" (cell pointer) vs "load for use" (cell value). Plan B mentioned the concept but didn't detail this mechanism
lower_let_body returns lambdas (Plan B): Plan B didn't account for lambdas inside let-binding initializers. Implementation changed lower_let_body to return Option<(MirFunctionBody, Vec<MirFunction>)>

Additions not in plans

lambda_advanced test project: 334-line comprehensive test suite exercising generic inference, chained maps, nested generics, optional/union patterns, shadowing, and complex composition
Builtin map/map_keys/map_values methods: Added to Array<T> and Map<K, V> in containers.baml with VM implementations — needed to test real lambda-as-argument patterns
216+ lines of TIR test infrastructure: Dedicated snapshot rendering for lambda signatures, lambda bodies, capture annotations, and compound argument expansion
LSP and onionskin exhaustive match updates: check.rs and compiler.rs needed Expr::Lambda arms

Items planned but not implemented

FFI/codegen for external targets (Python, TypeScript) — out of scope
PPIR streaming support for closures — out of scope
Closure inlining/devirtualization — out of scope
GC optimizations (escape analysis, open/closed upvalue transitions) — out of scope
Recursive closures (closures that capture themselves) — out of scope
Expression-body lambdas (without braces) — out of scope
Default lambda params — out of scope

How to verify it

Setup

git fetch
git checkout vbv/add-lambda-expression-support-to-baml-compiler

Automated Tests

# Full test suite
cargo test -p baml_tests

# Lambda-specific tests
cargo test -p baml_tests -- lambda_basic
cargo test -p baml_tests -- lambda_advanced
cargo test -p baml_tests -- lambda_errors

# Component tests
cargo test -p bex_vm
cargo test -p baml_compiler_parser
cargo test -p baml_compiler2_tir

Manual Testing

Review lambda_basic.baml — verify each lambda pattern (annotated, inferred, zero-param, capture, nested, generic, multi-param)
Review lambda_advanced.baml — verify complex patterns (chained maps, nested captures, higher-order return, IIFEs, shadowing)
Review lambda_errors.baml — verify each error case produces clear diagnostics
Review TIR snapshots — verify correct inferred types for all lambda expressions
Review MIR snapshots — verify [captured] annotations and make_closure rvalues with capture operands
Review codegen snapshots — verify cell-wrapping preamble, LoadDeref/StoreDeref, LoadCapture/StoreCapture, CaptureRef, MakeClosure instructions

Description for the changelog

Add lambda expression support to BAML: anonymous functions with (params) -> { body } syntax, bidirectional type inference, cell-based closure captures with shared mutation semantics, transitive capture propagation for nested lambdas, and higher-order container methods (Array.map, Map.map, Map.map_keys, Map.map_values).

Summary by CodeRabbit

New Features
- Lambda expressions: generics, parameter/return annotations, optional throws, block bodies, closures with captured variables.
- Container mapping helpers: Array.map, Map.map, Map.map_keys, Map.map_values.
Bug Fixes / Diagnostics
- New diagnostic for uninferrable lambda parameter types.
Tests
- Extensive new unit/integration tests exercising lambdas, captures, map usage, and error cases.
Runtime / Tooling
- VM, bytecode, GC, formatter and diagnostic integrations updated to support closures, capture cells, and new bytecode.

vercel · 2026-03-29T10:53:17Z

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coderabbitai · 2026-03-29T10:53:35Z

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📝 Walkthrough

Walkthrough

Adds end-to-end lambda/closure support (parsing, CST→AST lowering, HIR capture analysis, TIR inference/checking, MIR lowering, bytecode/runtime closure & cell support), Array/Map map* builtin declarations, formatter updates, extensive tests, and VM/GC/emitter integration for captures.

Changes

Cohort / File(s)	Summary
Parser & Syntax `baml_language/crates/baml_compiler_syntax/src/syntax_kind.rs`, `baml_language/crates/baml_compiler_parser/src/parser.rs`	Introduce `LAMBDA_EXPR` SyntaxKind and parsing for generic params, parameter lists, `->` return type, optional `throws`, block body, and lookahead heuristics.
CST → AST Lowering `baml_language/crates/baml_compiler2_ast/src/lower_expr_body.rs`, `baml_language/crates/baml_compiler2_ast/src/ast.rs`, `baml_language/crates/baml_compiler2_ast/src/lower_cst.rs`	Lower lambda CST into `Expr::Lambda(Box<FunctionDef>)`, add `lower_lambda_expr`, and promote some lowering helpers to `pub(crate)`.
HIR / Capture Analysis `baml_language/crates/baml_compiler2_hir/src/builder.rs`, `baml_language/crates/baml_compiler2_hir/src/semantic_index.rs`	Create lambda scopes, seed params, perform capture resolution, and record captures; add `captures` and `captured_names` to `ScopeBindings`.
TIR: Inference & Checking `baml_language/crates/baml_compiler2_tir/src/builder.rs`, `.../infer_context.rs`, `.../normalize.rs`, `.../inference.rs`	Add lambda inference/checking (including save/restore of inference state), `infer_lambda_body` helper, new `CannotInferLambdaParamType` error, two-pass call-site inference to handle lambda args, and subtype rule adjustments for Optional/Union.
MIR: IR, Lowering & Cleanup `baml_language/crates/baml_compiler2_mir/src/ir.rs`, `.../lower.rs`, `.../builder.rs`, `.../cleanup.rs`, `.../analysis.rs`, `.../pretty.rs`	Extend MIR with `MirFunction.lambdas`, `Rvalue::MakeClosure`, `Place::Capture`, and `LocalDecl.is_captured`; lower lambdas to child MIR, thread scope-aware type maps, and update cleanup/analysis/pretty to handle captures/closures.
Emit / Pull Semantics / Codegen `baml_language/crates/baml_compiler2_emit/src/lib.rs`, `.../emit.rs`, `.../pull_semantics.rs`, `.../stack_carry.rs`	Add codegen context fields for precompiled lambdas, new sink APIs (`make_closure`,`load_capture`,`store_capture_value`), stack simulation updates, closure emission (MakeClosure/MakeCell), and capture-load/store handling.
Bytecode & Runtime Types `baml_language/crates/bex_vm_types/src/bytecode.rs`, `baml_language/crates/bex_vm_types/src/types.rs`	Add bytecode instructions for closures/cells/captures and runtime types `Object::Closure` and `Object::Cell` plus corresponding structs and ObjectType variants.
VM & Heap Integration `baml_language/crates/bex_vm/src/vm.rs`, `baml_language/crates/bex_heap/src/gc.rs`, `baml_language/crates/bex_heap/src/accessor.rs`, `baml_language/crates/bex_engine/src/conversion.rs`, `babl_language/crates/bex_heap/src/heap_debugger/real.rs`	VM handlers for closure/cell instructions, GC tracing/forwarding and frame-root handling, conversion/accessor rejections for closures/cells, and heap invariant checks/trace/fixup for closures and cells.
VM Packaging & Formatting `baml_language/crates/bex_vm/src/package_baml/...`, `baml_language/crates/bex_vm/src/debug.rs`, `.../unstable.rs`, `.../root.rs`, `baml_language/crates/bex_vm/src/package_baml/array.rs`, `.../map.rs`	Formatting/debug updates for closures/cells, deep-copy allocation for closures/cells, and added stub `PackageBaml` `map`/`map_keys`/`map_values` implementations that currently `todo!()` panic.
Formatter & AST Printing `baml_language/crates/baml_fmt/src/ast/expressions.rs`, `.../tokens.rs`, `.../lib.rs`	Add `LambdaExpr`, `GenericParamList`, `ThrowsClause`, `Throws` token, formatter printing for lambdas, and idempotency tests.
Tests & Snapshots `baml_language/crates/baml_tests/...`, `baml_language/crates/baml_tests/src/compiler2_tir/mod.rs`, `baml_language/crates/baml_tests/tests/lambdas.rs`	Add many BAML test projects (basic/advanced/errors), Rust async runtime tests, and TIR/HIR snapshot rendering for lambda signatures, bodies, and capture annotations.
Builtins Declarations `baml_language/crates/baml_builtins2/baml_std/baml/containers.baml`	Declare `Array.map`, `Map.map`, `Map.map_keys`, and `Map.map_values` methods (implemented via `$rust_function`).
Small API / Visibility `baml_language/crates/baml_compiler2_ast/src/lower_cst.rs`, `baml_language/crates/baml_compiler2_mir/src/builder.rs`	Promote some lowering helpers to `pub(crate)`, add MirBuilder accessors, and initialize `LocalDecl.is_captured = false` in locals.

Sequence Diagram(s)

sequenceDiagram
    participant Src as Source
    participant Parser as Parser
    participant CST as CST
    participant Lower as Lowering/AST
    participant HIR as HIR/Scopes
    participant TIR as TIR/Infer
    participant MIR as MIR/Lower
    participant Codegen as Codegen/Emit
    participant VM as VM/Runtime

    Src->>Parser: parse lambda syntax (<...>(params) -> { ... })
    Parser->>CST: produce LAMBDA_EXPR node
    CST->>Lower: lower_lambda_expr -> Expr::Lambda(FunctionDef)
    Lower->>HIR: create lambda scope, register params
    HIR->>TIR: infer_lambda_body / type-check lambda
    TIR->>MIR: lower lambda into child MirFunction + Rvalue::MakeClosure
    MIR->>Codegen: collect/compile nested lambdas, emit MakeClosure/MakeCell
    Codegen->>VM: runtime allocates Closure/Cell and wires captures

Estimated Code Review Effort

🎯 5 (Critical) | ⏱️ ~120 minutes

Possibly related PRs

Stack-carry soundness + shared pull semantics #3135 — overlaps on pull-model traversal and stack-carry / emit integration; directly related to closure/capture emission changes.
VM cleanup: remove dead code, refactor watch graph, fix GC tracing #3108 — touches VM GC/frame forwarding and bytecode/VM internals used by closure/cell support.
Integration/canary compiler2 merge #3217 — related to builtin container APIs and earlier lambda/closure integration work.

Suggested reviewers

imalsogreg

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The pull request title clearly summarizes the main change: adding lambda expression support to the BAML compiler, which aligns directly with the extensive changes across parser, AST, type inference, MIR, emit, and runtime components.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

Create PR with unit tests
Commit unit tests in branch vbv/add-lambda-expression-support-to-baml-compiler

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Actionable comments posted: 19

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

baml_language/crates/baml_compiler_parser/src/parser.rs (1)

3562-3599: 🧹 Nitpick | 🔵 Trivial

Add parser-level tests for the new lambda disambiguation branches.

parse_primary_expr now relies on custom ( / < lookahead to choose between lambdas and non-lambda expressions. A few unit tests in this module for (x) -> {}, <T>(x) -> {}, (x), and nested parameter types would make regressions much easier to localize than end-to-end fixtures alone.

As per coding guidelines, **/*.rs: Prefer writing Rust unit tests over integration tests where possible.

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 06170aa1-cc8f-4342-8db1-3a9d22fdd0b7

📥 Commits

Reviewing files that changed from the base of the PR and between 1388039 and 0b6cc48.

⛔ Files ignored due to path filters (37)

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📒 Files selected for processing (22)

baml_language/crates/baml_builtins2/baml_std/baml/containers.baml
baml_language/crates/baml_compiler2_ast/src/ast.rs
baml_language/crates/baml_compiler2_ast/src/lower_cst.rs
baml_language/crates/baml_compiler2_ast/src/lower_expr_body.rs
baml_language/crates/baml_compiler2_hir/src/builder.rs
baml_language/crates/baml_compiler2_mir/src/lower.rs
baml_language/crates/baml_compiler2_tir/src/builder.rs
baml_language/crates/baml_compiler2_tir/src/infer_context.rs
baml_language/crates/baml_compiler2_tir/src/normalize.rs
baml_language/crates/baml_compiler_parser/src/parser.rs
baml_language/crates/baml_compiler_syntax/src/syntax_kind.rs
baml_language/crates/baml_fmt/src/ast/expressions.rs
baml_language/crates/baml_fmt/src/ast/tokens.rs
baml_language/crates/baml_fmt/src/lib.rs
baml_language/crates/baml_lsp2_actions/src/check.rs
baml_language/crates/baml_tests/projects/lambda_advanced/lambda_advanced.baml
baml_language/crates/baml_tests/projects/lambda_basic/lambda_basic.baml
baml_language/crates/baml_tests/projects/lambda_errors/lambda_errors.baml
baml_language/crates/baml_tests/src/compiler2_tir/mod.rs
baml_language/crates/bex_vm/src/package_baml/array.rs
baml_language/crates/bex_vm/src/package_baml/map.rs
baml_language/crates/tools_onionskin/src/compiler.rs

baml_language/crates/baml_builtins2/baml_std/baml/containers.baml

baml_language/crates/baml_compiler_parser/src/parser.rs

baml_language/crates/baml_compiler2_ast/src/lower_expr_body.rs

baml_language/crates/baml_compiler2_hir/src/builder.rs

baml_language/crates/baml_tests/projects/lambda_advanced/lambda_advanced.baml

baml_language/crates/baml_tests/src/compiler2_tir/mod.rs

baml_language/crates/bex_vm/src/package_baml/array.rs

baml_language/crates/bex_vm/src/package_baml/map.rs

github-actions · 2026-03-29T11:07:37Z

Binary size checks passed

✅ 7 passed

	Artifact	Platform	Gzip	Baseline	Delta	Status
✅	`bridge_cffi`	Linux	4.3 MB	5.7 MB	-1.4 MB (-24.6%)	OK
✅	`bridge_cffi-stripped`	Linux	2.8 MB	4.3 MB	-1.5 MB (-35.4%)	OK
✅	`bridge_cffi`	macOS	3.5 MB	4.6 MB	-1.1 MB (-24.1%)	OK
✅	`bridge_cffi-stripped`	macOS	2.2 MB	3.5 MB	-1.2 MB (-35.5%)	OK
✅	`bridge_cffi`	Windows	3.5 MB	4.6 MB	-1.1 MB (-24.6%)	OK
✅	`bridge_cffi-stripped`	Windows	2.3 MB	3.5 MB	-1.3 MB (-35.3%)	OK
✅	`bridge_wasm`	WASM	2.2 MB	3.0 MB	-738.9 KB (-24.9%)	OK

Generated by cargo size-gate · workflow run

codspeed-hq · 2026-03-29T11:08:47Z

Merging this PR will not alter performance

⚠️

Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

✅ 15 untouched benchmarks
⏩ 98 skipped benchmarks¹

_{Comparing vbv/add-lambda-expression-support-to-baml-compiler (5669b4c) with canary (fa79810)}

98 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

coderabbitai

Actionable comments posted: 12

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

baml_language/crates/bex_vm_types/src/types.rs (1)
809-817: ⚠️ Potential issue | 🟠 Major

Object::Variant is still classified as enum.

While touching ObjectType::of(), the variant arm below still returns Self::Enum. That keeps runtime type checks and diagnostics wrong for actual enum values.
🩹 Proposed fix
         match ob {
             Object::Function(func) => Self::Function(FunctionType::from(&func.kind)),
             Object::Closure(_) => Self::Closure,
             Object::Cell(_) => Self::Cell,
             Object::Class(_) => Self::Class,
             Object::Instance(_) => Self::Instance,
             Object::Enum(_) => Self::Enum,
-            Object::Variant(_) => Self::Enum,
+            Object::Variant(_) => Self::Variant,
             Object::String(_) => Self::String,
             Object::Array(_) => Self::Array,
             Object::Map(_) => Self::Map,

♻️ Duplicate comments (2)

baml_language/crates/baml_tests/src/compiler2_tir/mod.rs (2)
253-284: ⚠️ Potential issue | 🟡 Minor

Render lambda throws clauses in signatures.

FunctionDef::throws is still ignored here, so throwing lambdas snapshot exactly like non-throwing ones in both the TIR and HIR renderers.
🩹 Proposed fix
 let ret = func_def
 .return_type
 .as_ref()
 .map(|te| format!(" {}", type_expr_to_string(&te.expr)))
 .unwrap_or_default();
+ let throws = func_def
+ .throws
+ .as_ref()
+ .map(|te| format!(" throws {}", type_expr_to_string(&te.expr)))
+ .unwrap_or_default();
 let generics = if func_def.generic_params.is_empty() {
 String::new()
 } else {
 format!(
 "<{}>",
@@
- format!("{generics}({}) ->{ret} {{ ... }}", params.join(", "))
+ format!("{generics}({}) ->{ret}{throws} {{ ... }}", params.join(", "))
402-410: ⚠️ Potential issue | 🟠 Major

Keep lambda body snapshots typed.

This path still drops into render_expr_body_untyped, so inferred parameter, capture, and return types inside lambdas stop being asserted by the TIR snapshots. Please plumb the lambda scope’s own ScopeInference here instead of using the untyped fallback.

Also applies to: 447-497

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⛔ Files ignored due to path filters (10)

baml_language/crates/baml_tests/snapshots/lambda_advanced/baml_tests__lambda_advanced__03_hir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_advanced/baml_tests__lambda_advanced__04_5_mir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_advanced/baml_tests__lambda_advanced__04_tir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_advanced/baml_tests__lambda_advanced__06_codegen.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_basic/baml_tests__lambda_basic__03_hir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_basic/baml_tests__lambda_basic__04_5_mir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_basic/baml_tests__lambda_basic__04_tir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_basic/baml_tests__lambda_basic__06_codegen.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_errors/baml_tests__lambda_errors__04_5_mir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_errors/baml_tests__lambda_errors__06_codegen.snap is excluded by !**/*.snap

📒 Files selected for processing (29)

baml_language/crates/baml_compiler2_emit/src/analysis.rs
baml_language/crates/baml_compiler2_emit/src/emit.rs
baml_language/crates/baml_compiler2_emit/src/lib.rs
baml_language/crates/baml_compiler2_emit/src/pull_semantics.rs
baml_language/crates/baml_compiler2_emit/src/stack_carry.rs
baml_language/crates/baml_compiler2_emit/src/verifier.rs
baml_language/crates/baml_compiler2_hir/src/builder.rs
baml_language/crates/baml_compiler2_hir/src/semantic_index.rs
baml_language/crates/baml_compiler2_mir/src/builder.rs
baml_language/crates/baml_compiler2_mir/src/cleanup.rs
baml_language/crates/baml_compiler2_mir/src/ir.rs
baml_language/crates/baml_compiler2_mir/src/lower.rs
baml_language/crates/baml_compiler2_mir/src/pretty.rs
baml_language/crates/baml_compiler2_tir/src/builder.rs
baml_language/crates/baml_compiler2_tir/src/inference.rs
baml_language/crates/baml_tests/src/compiler2_tir/mod.rs
baml_language/crates/baml_tests/tests/lambdas.rs
baml_language/crates/bex_engine/src/conversion.rs
baml_language/crates/bex_engine/src/lib.rs
baml_language/crates/bex_heap/src/accessor.rs
baml_language/crates/bex_heap/src/gc.rs
baml_language/crates/bex_heap/src/heap_debugger/real.rs
baml_language/crates/bex_vm/src/debug.rs
baml_language/crates/bex_vm/src/package_baml/root.rs
baml_language/crates/bex_vm/src/package_baml/unstable.rs
baml_language/crates/bex_vm/src/vm.rs
baml_language/crates/bex_vm_types/src/bytecode.rs
baml_language/crates/bex_vm_types/src/types.rs
baml_language/crates/tools_onionskin/src/compiler.rs

baml_language/crates/baml_compiler2_emit/src/analysis.rs

baml_language/crates/baml_compiler2_emit/src/emit.rs

baml_language/crates/baml_compiler2_emit/src/pull_semantics.rs

baml_language/crates/baml_compiler2_mir/src/cleanup.rs

baml_language/crates/baml_compiler2_mir/src/lower.rs

baml_language/crates/baml_compiler2_tir/src/builder.rs

baml_language/crates/baml_tests/src/compiler2_tir/mod.rs

baml_language/crates/bex_engine/src/lib.rs

baml_language/crates/bex_heap/src/gc.rs

baml_language/crates/bex_vm/src/package_baml/root.rs

coderabbitai

Actionable comments posted: 3

♻️ Duplicate comments (1)

baml_language/crates/baml_compiler2_tir/src/builder.rs (1)
4287-4294: ⚠️ Potential issue | 🟠 Major

Don't leak lambda-local ExprId state back into the parent builder.

infer_lambda_body isolates expressions and bindings, but resolutions, catch_residual_throws, and exhaustive_matches still accumulate lambda-local entries keyed by the lambda arena's ExprIds. Those ids can collide with the parent scope and corrupt member resolution, throw tracking, or match-exhaustiveness data after the lambda returns.
Suggested fix
         let saved_generic_params = self.generic_params.clone();
         let saved_expressions = std::mem::take(&mut self.expressions);
         let saved_bindings = std::mem::take(&mut self.bindings);
+        let saved_resolutions = std::mem::take(&mut self.resolutions);
+        let saved_catch_residual_throws = std::mem::take(&mut self.catch_residual_throws);
+        let saved_exhaustive_matches = std::mem::take(&mut self.exhaustive_matches);
@@
         let lambda_expressions = std::mem::replace(&mut self.expressions, saved_expressions);
         self.bindings = saved_bindings;
+        self.resolutions = saved_resolutions;
+        self.catch_residual_throws = saved_catch_residual_throws;
+        self.exhaustive_matches = saved_exhaustive_matches;
         self.locals = saved_locals;
         self.declared_types = saved_declared;
         self.declared_return_ty = saved_return_ty;
Also applies to: 4357-4363

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⛔ Files ignored due to path filters (21)

baml_language/crates/baml_tests/snapshots/__baml_std__/baml_tests____baml_std____03_hir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/__baml_std__/baml_tests____baml_std____04_5_mir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/__baml_std__/baml_tests____baml_std____04_tir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/__baml_std__/baml_tests____baml_std____06_codegen.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_advanced/baml_tests__lambda_advanced__01_lexer__lambda_advanced.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_advanced/baml_tests__lambda_advanced__02_parser__lambda_advanced.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_advanced/baml_tests__lambda_advanced__03_hir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_advanced/baml_tests__lambda_advanced__04_5_mir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_advanced/baml_tests__lambda_advanced__04_tir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_advanced/baml_tests__lambda_advanced__06_codegen.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_advanced/baml_tests__lambda_advanced__10_formatter__lambda_advanced.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_basic/baml_tests__lambda_basic__03_hir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_basic/baml_tests__lambda_basic__04_tir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_errors/baml_tests__lambda_errors__01_lexer__lambda_errors.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_errors/baml_tests__lambda_errors__02_parser__lambda_errors.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_errors/baml_tests__lambda_errors__03_hir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_errors/baml_tests__lambda_errors__04_5_mir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_errors/baml_tests__lambda_errors__04_tir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_errors/baml_tests__lambda_errors__05_diagnostics.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_errors/baml_tests__lambda_errors__06_codegen.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_errors/baml_tests__lambda_errors__10_formatter__lambda_errors.snap is excluded by !**/*.snap

📒 Files selected for processing (6)

baml_language/crates/baml_builtins2/baml_std/baml/containers.baml
baml_language/crates/baml_compiler2_tir/src/builder.rs
baml_language/crates/baml_tests/projects/lambda_advanced/lambda_advanced.baml
baml_language/crates/baml_tests/projects/lambda_errors/lambda_errors.baml
baml_language/crates/baml_tests/src/compiler2_tir/mod.rs
baml_language/crates/bex_vm/src/package_baml/map.rs

baml_language/crates/baml_compiler2_tir/src/builder.rs

coderabbitai

Actionable comments posted: 5

♻️ Duplicate comments (3)

baml_language/crates/baml_tests/src/compiler2_tir/mod.rs (1)

253-292: ⚠️ Potential issue | 🟡 Minor

Use an HIR-aware formatter for lambda signatures.

This shared helper still hard-codes type_expr_to_string(), so the HIR path prints lambda param/return/throws annotations without the package qualification that render_hir2() preserves elsewhere. Please split this into TIR/HIR variants or pass a type-formatting callback.

Also applies to: 1381-1395

baml_language/crates/baml_compiler2_tir/src/builder.rs (2)

693-739: ⚠️ Potential issue | 🟠 Major

Lambda-arg inference is still source-order dependent.

Pass 2 still visits lambda arguments once in source order. If an earlier lambda needs a type variable that only a later lambda binds, the earlier one still falls back to synthesis and can emit CannotInferLambdaParamType for an otherwise-valid call. Defer unresolved lambda args and retry until the bindings map stops changing.

838-890: ⚠️ Potential issue | 🟠 Major

Check-mode lambdas still ignore local generics and can widen the expected return.

These annotation lowerings only see self.generic_params, so lambda-local <T> annotations still become Unknown here even though synthesis mode handles them. effective_ret also takes the explicit annotation without first checking annotation <: expected_ret, which accepts wider return contracts than the expected function type.

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baml_language/crates/baml_compiler2_hir/src/builder.rs
baml_language/crates/baml_compiler2_hir/src/semantic_index.rs
baml_language/crates/baml_compiler2_mir/src/lower.rs
baml_language/crates/baml_compiler2_tir/src/builder.rs
baml_language/crates/baml_compiler2_tir/src/inference.rs
baml_language/crates/baml_tests/src/compiler2_tir/mod.rs
baml_language/crates/baml_tests/tests/lambdas.rs

baml_language/crates/baml_compiler2_tir/src/builder.rs

baml_language/crates/baml_compiler2_tir/src/inference.rs

baml_language/crates/baml_tests/src/compiler2_tir/mod.rs

baml_language/crates/baml_tests/tests/lambdas.rs

coderabbitai

Actionable comments posted: 2

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

baml_language/crates/baml_tests/src/compiler2_tir/mod.rs (1)

475-500: ⚠️ Potential issue | 🟡 Minor

IIFEs and nested lambda call sites still hide their bodies in TIR snapshots.

The typed Expr::Call path only expands compound arguments, not a compound callee, and render_expr_body_untyped() has no call-specific recursion at all. (() -> { ... })() and higher-order calls inside lambda bodies therefore collapse back to the { ... } placeholder, which underasserts some of the new closure cases.

Also applies to: 511-558

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⛔ Files ignored due to path filters (3)

baml_language/crates/baml_tests/snapshots/lambda_advanced/baml_tests__lambda_advanced__04_5_mir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_basic/baml_tests__lambda_basic__04_5_mir.snap is excluded by !**/*.snap
baml_language/crates/baml_tests/snapshots/lambda_errors/baml_tests__lambda_errors__04_5_mir.snap is excluded by !**/*.snap

📒 Files selected for processing (5)

baml_language/crates/baml_compiler2_mir/src/pretty.rs
baml_language/crates/baml_fmt/src/ast/expressions.rs
baml_language/crates/baml_tests/src/compiler2_tir/mod.rs
baml_language/crates/baml_tests/tests/lambdas.rs
baml_language/crates/bex_engine/src/lib.rs

baml_language/crates/baml_tests/src/compiler2_tir/mod.rs

baml_language/crates/baml_tests/tests/lambdas.rs

Create lambda_basic and lambda_errors test projects with BAML files exercising lambda syntax (annotated params, inferred return types, captures, nested lambdas, generics, error cases). Generate baseline snapshots showing expected parse errors before parser support is added.

Add LAMBDA_EXPR to SyntaxKind, implement looks_like_lambda and looks_like_generic_lambda predicates for disambiguating parenthesized expressions from lambda expressions, and add parse_lambda_expr to handle the full lambda syntax including optional generics, params, return type, throws clause, and block body.

Add Lambda(Box<FunctionDef>) to the Expr enum with CST lowering that creates a fresh ExprBody for the lambda's block. Register lambda scopes in HIR with ScopeKind::Lambda and seed param bindings. Add MIR panic stub for lambda expressions. Wire up exhaustive match arms in TIR, test harness, and tools_onionskin.

Implement synthesis and checking modes for Expr::Lambda in the TIR. Lambdas in synthesis mode require annotated param types; in checking mode, unannotated params get their types from the expected function type context. Variable capture works via save/restore of locals. Fix partially-resolved function type checking so lambdas passed to generic higher-order functions get contextual param types even when the return type contains unresolved type vars.

Handle LAMBDA_EXPR CST nodes in the formatter with proper printing of optional generic params, parameter list, arrow, optional return type, optional throws clause, and block body. Add GenericParamList and ThrowsClause formatter types. Include idempotency unit tests.

Add parse_lambda_parameter_list/parse_lambda_parameter that allow type annotations to be omitted (e.g. (x) -> { x * 2 }). This removes the spurious E0010 parser error for unannotated lambda params. Update HIR and TIR snapshot rendering to recursively print lambda bodies instead of just showing "<lambda>", making it possible to verify the internal expression structure.

The formatter expects if-conditions wrapped in parentheses (PAREN_EXPR), matching BAML's standard syntax. Change `if x < 0` to `if (x < 0)` in the lambda_basic test so the formatter can round-trip the file correctly.

Replace the catch-all <stmt> placeholder in render_stmt_untyped with proper rendering of throw, return, assign, break, continue, and assert statements so lambda body snapshots show full expression trees.

When a call expression has compound arguments (lambdas, blocks, if-expressions), expand them recursively below the call line so lambda bodies passed to higher-order functions are visible.

Add higher-order map methods to Array<T> and Map<K,V> with VM stubs. Array.map(f: (T) -> U) -> U[] and Map.map/map_keys/map_values enable lambda expressions as arguments to container methods.

In resolve_builtin_method, add method-level generic params (e.g. U in map) as TypeVar entries in the bindings map before lowering the method signature. This allows method generics to survive as TypeVars through lower_type_expr_with_generics, enabling call-site inference to bind them from argument types (e.g. U=int from a lambda returning int). Previously method generics became Unknown, causing map() to return unknown[] instead of int[].

When inferring types for a generic lambda like <T>(x: T) -> T { x }, combine the lambda's own generic_params with the parent scope's generic_params before calling lower_type_expr_in_ns. Previously only parent generics were passed, so T was unrecognized and became Unknown.

Identify captured variables at HIR time in SemanticIndexBuilder. For each lambda scope, walk the body's ExprBody to find single-segment Path names that resolve to ancestor scope bindings (up to the Function boundary). Record captures on ScopeBindings and mark defining scopes' captured_names for downstream MIR cell-wrapping decisions.

…tructions, MIR data structures Add Object::Closure and Object::Cell variants, 6 new bytecode instructions (MakeClosure, MakeCell, LoadDeref, StoreDeref, LoadCapture, StoreCapture), Rvalue::MakeClosure, MirFunction.lambdas, LocalDecl.is_captured, GC tracing, and VM execution handlers. All additive — no existing behavior changes.

…osures - Save/restore self.expressions and self.bindings in infer_lambda_body to prevent arena ID collisions between lambda and parent scopes - Change expr_types and pat_types keys from bare AstExprId/AstPatId to (FileScopeId, AstExprId/AstPatId) for proper scope isolation - Populate ScopeKind::Lambda with real inference in inference.rs - Add PullSink::make_closure, StackifyCodegen::make_closure, and StackCarryPullSink::make_closure for emit layer support

Replace MIR panic stub with real lambda lowering via save/restore on LoweringContext. Lambda bodies compile to separate MirFunctions stored in parent's lambdas vec. Pass 4 recursively compiles lambda children and maps lambda_idx to ObjectIndex for MakeClosure emission. Non-capturing lambdas and IIFEs now compile and execute correctly.

Add Place::Capture(usize) to MIR for captured variable access in lambda bodies. Wire HIR captured_names into LocalDecl.is_captured. Emit MakeCell preamble for captured locals, LoadDeref/StoreDeref in parent functions, LoadCapture/StoreCapture in lambda bodies. Captures are passed as operands to MakeClosure and shared via Cell objects for mutation semantics.

Add CaptureRef instruction for forwarding cell pointers to inner closures without dereferencing. Fix transitive capture propagation to avoid duplicate entries. Mark lambda params as captured when nested lambdas reference them. Add 7 execution tests: shared mutation counter, transitive captures across 3 scopes, IIFE returning closure, multiple closures sharing cells, deep 3-level nesting, and loop variable accumulation.

…snapshots, fix test types - Report type expression diagnostics in all 4 lambda `lower_type_expr_in_ns` callsites (synthesis param/return, checking param/return) instead of silently dropping them. Added `test_unknown_param_type` and `test_unknown_return_type` error test cases that now correctly produce `unresolved type: NonExistentType`. - Render `throws` clauses in `format_lambda_signature` for TIR/HIR snapshots. - Fix `test_nested_map` return type from `int[]` to `int[][]`. - Remove unused `map_keys`/`map_values` VM stubs (defined in BAML source, not `$rust_function`). Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

@watch

…hrough captures Fix D: When a lambda body assigns a function call result to a captured variable (e.g. `x = helper()`), the MIR builder panicked with "Call destination must be a local place". Now lower_call routes non-Local destinations through a temp local, then assigns to the real destination. Fix F: Thread `DefinitionSite` through HIR capture tracking for shadowing safety. `ScopeBindings.captures` is now `Vec<(Name, DefinitionSite)>` instead of `Vec<Name>`, uniquely identifying which declaration is captured. Mark `is_captured` at the capture-operand building site in MIR (where the exact Local is known) instead of relying solely on the name-based post-pass. Also adds 9 execution tests probing issues identified in PR review: - Issue A (virtual inlining): 2 tests — both pass - Issue B (@watch + cells): 1 test — passes - Issue D (capture call dest): 1 test — was crashing, now fixed - Issue E (resolution key collision): 2 tests — both pass - Issue F (shadowing captures): 2 tests — ignored (BAML disallows shadowing) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Tests for Issue B: verify that `watch let` variables captured by lambdas work correctly with cell wrapping. Both `watch let x` with lambda-only mutation and mixed parent + lambda mutation produce correct values. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

…t, HIR type formatting - Fix parked VMs missing frame-pointer forwarding after GC. The active VM path already called apply_frame_forwarding but parked VMs did not, leaving stale frame.function pointers after moving GC. - Add `// lambda[idx]` labels to MIR pretty printer so child lambdas are unambiguously identified by their MakeClosure slot index. - Propagate multi_lined from ThrowsClause inner type print so parent layout decisions get correct signal. - Add format_lambda_signature_hir for HIR-qualified type names in lambda signatures (uses prefix for local type names). Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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hellovai added 12 commits March 30, 2026 14:55

Fix lambda test file to use parenthesized if-condition

d55d5a7

The formatter expects if-conditions wrapped in parentheses (PAREN_EXPR), matching BAML's standard syntax. Change `if x < 0` to `if (x < 0)` in the lambda_basic test so the formatter can round-trip the file correctly.

Render all statement types in lambda body snapshots

eeb0536

Replace the catch-all <stmt> placeholder in render_stmt_untyped with proper rendering of throw, return, assign, break, continue, and assert statements so lambda body snapshots show full expression trees.

Expand compound arguments in call expression TIR snapshots

7cf74d2

When a call expression has compound arguments (lambdas, blocks, if-expressions), expand them recursively below the call line so lambda bodies passed to higher-order functions are visible.

Add map/map_keys/map_values builtins for Array and Map containers

07e396e

Add higher-order map methods to Array<T> and Map<K,V> with VM stubs. Array.map(f: (T) -> U) -> U[] and Map.map/map_keys/map_values enable lambda expressions as arguments to container methods.

hellovai and others added 11 commits March 30, 2026 14:56

regenerate .snap files

5abe7b2

hellovai force-pushed the vbv/add-lambda-expression-support-to-baml-compiler branch from 21fa705 to 5abe7b2 Compare March 30, 2026 22:00

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make scneario better + remove parser_stress tests

fabbfd8

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hellovai enabled auto-merge March 30, 2026 22:39

remove stress tests

5669b4c

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Merged via the queue into canary with commit 7d24545 Mar 30, 2026
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hellovai deleted the vbv/add-lambda-expression-support-to-baml-compiler branch March 30, 2026 23:38

This was referenced Apr 1, 2026

baml-language/fix: allow parsing 'field: string @alias("asdf") @stream.done' #3314

Merged

implement typed rethrows for higher-order functions #3343

Open

This was referenced Apr 9, 2026

baml grep and baml describe - agent-oriented semantic search tools #3347

Merged

Native function continuations #3353

Merged

Fix closure-over-loop-variable bug, skip MIR on errors, void test bodies #3355

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What problems was I solving

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1. Syntax & Parser

2. AST Lowering

3. HIR Scope Registration & Capture Analysis

4. TIR Type Inference

5. Formatter

6. Container Builtins

7. VM Structural Foundation

8. MIR IR & Lowering

9. Emit Layer

10. Tests

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hellovai commented Mar 29, 2026 •

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