Section 7C: Collections & Iteration

Goal: Collection methods, iterator traits, and Debug trait

SPEC: spec/annex-c-built-in-functions.md DESIGN: modules/prelude.md

7C.1 Collection Functions

NOTE: len and is_empty are being moved from free functions to methods on collections (see 7C.4). The free function forms are deprecated in favor of .len() and .is_empty() methods. Keep backward compatibility during transition, then remove free functions.

• Implement: len(x) — spec/annex-c-built-in-functions.md § len (deprecated, use .len()) [done] (2026-02-10)

  • Rust Tests: Evaluator builtin — len function tests
  • Ori Tests: Used extensively in test suite via .len() method
  • LLVM Support: LLVM codegen for len function
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — len function codegen
  • AOT Tests: No AOT coverage yet (free function form; method form covered in 7C.4)

• Implement: is_empty(x) — spec/annex-c-built-in-functions.md § is_empty (deprecated, use .is_empty()) [done] (2026-02-10)

  • Rust Tests: Evaluator builtin — is_empty function tests
  • Ori Tests: tests/spec/traits/core/is_empty.ori — 15+ tests
  • LLVM Support: LLVM codegen for is_empty function
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — is_empty function codegen
  • AOT Tests: No AOT coverage yet (free function form; method form covered in 7C.4)

7C.2 Collection Methods on [T]

Design Principle: Lean core, rich libraries. Data transformation is stdlib, not compiler patterns.

• Implement: [T].map(f: T -> U) -> [U] — modules/prelude.md § List [done] (2026-02-10)

  • Rust Tests: Evaluator method dispatch — list map tests
  • Ori Tests: Used in tests/spec/types/primitives.ori, tests/spec/lexical/keywords.ori
  • LLVM Support: LLVM codegen for list map
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list map codegen
  • AOT Tests: ori_llvm/tests/aot/iterators.rs — test_iter_map (iterator-level .map(), 1 test); ori_llvm/tests/aot/collections_ext.rs — test_coll_list_iter_map_collect_length (1 test)

• Implement: [T].filter(f: T -> bool) -> [T] — modules/prelude.md § List [done] (2026-02-10)

  • Rust Tests: Evaluator method dispatch — list filter tests
  • Ori Tests: tests/spec/lexical/operators.ori — list.filter(predicate: x -> x % 2 == 0)
  • LLVM Support: LLVM codegen for list filter
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list filter codegen
  • AOT Tests: ori_llvm/tests/aot/iterators.rs — test_iter_filter (iterator-level .filter(), 1 test); ori_llvm/tests/aot/collections_ext.rs — test_coll_list_iter_filter_count (1 test)

• Implement: [T].fold(initial: U, f: (U, T) -> U) -> U — modules/prelude.md § List [done] (2026-02-10)

  • Rust Tests: Evaluator method dispatch — list fold tests
  • Ori Tests: tests/spec/lexical/keywords.ori — [1,2,3].fold(initial: 0, combine: (a,b) -> a + b)
  • LLVM Support: LLVM codegen for list fold
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list fold codegen
  • AOT Tests: ori_llvm/tests/aot/iterators.rs — test_iter_fold_sum, test_iter_fold_with_filter (iterator-level .fold(), 2 tests); ori_llvm/tests/aot/collections_ext.rs — test_coll_list_iter_sum_via_fold (1 test)

• Implement: [T].find(f: T -> bool) -> Option<T> — modules/prelude.md § List

  • Rust Tests: ori_eval/src/methods.rs — list find tests
  • Ori Tests: tests/spec/stdlib/list_methods.ori
  • LLVM Support: LLVM codegen for list find
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list find codegen
  • AOT Tests: ori_llvm/tests/aot/iterators.rs — test_iter_find_some, test_iter_find_none (iterator-level .find(), 2 tests)

• Implement: [T].any(f: T -> bool) -> bool — modules/prelude.md § List

  • Rust Tests: ori_eval/src/methods.rs — list any tests
  • Ori Tests: tests/spec/stdlib/list_methods.ori
  • LLVM Support: LLVM codegen for list any
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list any codegen
  • AOT Tests: ori_llvm/tests/aot/iterators.rs — test_iter_any_true, test_iter_any_false (iterator-level .any(), 2 tests); ori_llvm/tests/aot/collections_ext.rs — test_coll_list_iter_any_all (1 test)

• Implement: [T].all(f: T -> bool) -> bool — modules/prelude.md § List

  • Rust Tests: ori_eval/src/methods.rs — list all tests
  • Ori Tests: tests/spec/stdlib/list_methods.ori
  • LLVM Support: LLVM codegen for list all
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list all codegen
  • AOT Tests: ori_llvm/tests/aot/iterators.rs — test_iter_all_true, test_iter_all_false (iterator-level .all(), 2 tests); ori_llvm/tests/aot/collections_ext.rs — test_coll_list_iter_any_all (1 test)

• Implement: [T].first() -> Option<T> — modules/prelude.md § List

  • Rust Tests: ori_eval/src/methods.rs — list first tests
  • Ori Tests: tests/spec/stdlib/list_methods.ori
  • LLVM Support: LLVM codegen for list first
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list first codegen
  • AOT Tests: ori_llvm/tests/aot/collections_ext.rs — test_coll_list_first (1 test, ignored: list.first() not in builtin table)

• Implement: [T].last() -> Option<T> — modules/prelude.md § List

  • Rust Tests: ori_eval/src/methods.rs — list last tests
  • Ori Tests: tests/spec/stdlib/list_methods.ori
  • LLVM Support: LLVM codegen for list last
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list last codegen
  • AOT Tests: ori_llvm/tests/aot/collections_ext.rs — test_coll_list_last (1 test, ignored: list.last() not in builtin table)

• Implement: [T].take(n: int) -> [T] — modules/prelude.md § List

  • Rust Tests: ori_eval/src/methods.rs — list take tests
  • Ori Tests: tests/spec/stdlib/list_methods.ori
  • LLVM Support: LLVM codegen for list take
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list take codegen
  • AOT Tests: ori_llvm/tests/aot/iterators.rs — test_iter_take (iterator-level take adapter, 1 test)

• Implement: [T].skip(n: int) -> [T] — modules/prelude.md § List

  • Rust Tests: ori_eval/src/methods.rs — list skip tests
  • Ori Tests: tests/spec/stdlib/list_methods.ori
  • LLVM Support: LLVM codegen for list skip
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list skip codegen
  • AOT Tests: ori_llvm/tests/aot/iterators.rs — test_iter_skip (iterator-level skip adapter, 1 test)

• Implement: [T].reverse() -> [T] — modules/prelude.md § List

  • Rust Tests: ori_eval/src/methods.rs — list reverse tests
  • Ori Tests: tests/spec/stdlib/list_methods.ori
  • LLVM Support: LLVM codegen for list reverse
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list reverse codegen
  • AOT Tests: ori_llvm/tests/aot/collections_ext.rs — test_coll_list_reverse (1 test, ignored: list.reverse() not in builtin table)

• Implement: [T].sort() -> [T] where T: Comparable — modules/prelude.md § List

  • Rust Tests: ori_eval/src/methods.rs — list sort tests
  • Ori Tests: tests/spec/stdlib/list_methods.ori
  • LLVM Support: LLVM codegen for list sort
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list sort codegen
  • AOT Tests: No AOT coverage yet

• Implement: [T].contains(value: T) -> bool where T: Eq — modules/prelude.md § List

  • Rust Tests: ori_eval/src/methods.rs — list contains tests
  • Ori Tests: tests/spec/stdlib/list_methods.ori
  • LLVM Support: LLVM codegen for list contains
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list contains codegen
  • AOT Tests: ori_llvm/tests/aot/collections_ext.rs — test_coll_list_contains (1 test, ignored: list.contains() not in builtin table)

• Implement: [T].push(value: T) -> [T] — modules/prelude.md § List

  • Rust Tests: ori_eval/src/methods.rs — list push tests
  • Ori Tests: tests/spec/stdlib/list_methods.ori
  • LLVM Support: LLVM codegen for list push
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list push codegen
  • AOT Tests: ori_llvm/tests/aot/collections_ext.rs — test_coll_list_push (1 test, ignored: list.push() not in builtin table)

• Implement: [T].concat(other: [T]) -> [T] — modules/prelude.md § List

  • Rust Tests: ori_eval/src/methods.rs — list concat tests
  • Ori Tests: tests/spec/stdlib/list_methods.ori
  • LLVM Support: LLVM codegen for list concat
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list concat codegen
  • AOT Tests: No AOT coverage yet

7C.3 Range Methods

• Implement: Range.map(f: T -> U) -> [U] — modules/prelude.md § Range

  • Rust Tests: ori_eval/src/methods.rs — Range.map tests
  • Ori Tests: tests/spec/stdlib/range_methods.ori
  • LLVM Support: LLVM codegen for Range.map
  • LLVM Rust Tests: ori_llvm/tests/range_tests.rs — Range.map codegen
  • AOT Tests: ori_llvm/tests/aot/iterators.rs — test_iter_map tests map on list iterator; test_chained_map_filter_take tests map on range-derived iterator

• Implement: Range.filter(f: T -> bool) -> [T] — modules/prelude.md § Range

  • Rust Tests: ori_eval/src/methods.rs — Range.filter tests
  • Ori Tests: tests/spec/stdlib/range_methods.ori
  • LLVM Support: LLVM codegen for Range.filter
  • LLVM Rust Tests: ori_llvm/tests/range_tests.rs — Range.filter codegen
  • AOT Tests: ori_llvm/tests/aot/iterators.rs — test_iter_filter tests filter on list iterator; test_chained_map_filter_take tests filter on range-derived iterator

• Implement: Range.fold(initial: U, f: (U, T) -> U) -> U — modules/prelude.md § Range

  • Rust Tests: ori_eval/src/methods.rs — Range.fold tests
  • Ori Tests: tests/spec/stdlib/range_methods.ori
  • LLVM Support: LLVM codegen for Range.fold
  • LLVM Rust Tests: ori_llvm/tests/range_tests.rs — Range.fold codegen
  • AOT Tests: ori_llvm/tests/aot/iterators.rs — test_iter_fold_sum, test_iter_fold_with_filter test fold on range-derived iterators via chaining

• Implement: Range.collect() -> [T] — modules/prelude.md § Range

  • Rust Tests: ori_eval/src/methods.rs — Range.collect tests
  • Ori Tests: tests/spec/stdlib/range_methods.ori
  • LLVM Support: LLVM codegen for Range.collect
  • LLVM Rust Tests: ori_llvm/tests/range_tests.rs — Range.collect codegen
  • AOT Tests: ori_llvm/tests/aot/iterators.rs — test_range_iter_collect (range .iter().collect() to list, 1 test)

• Implement: Range.contains(value: T) -> bool — modules/prelude.md § Range

  • Rust Tests: ori_eval/src/methods.rs — Range.contains tests
  • Ori Tests: tests/spec/stdlib/range_methods.ori
  • LLVM Support: LLVM codegen for Range.contains
  • LLVM Rust Tests: ori_llvm/tests/range_tests.rs — Range.contains codegen
  • AOT Tests: No AOT coverage yet

7C.4 Collection Methods (len, is_empty)

Move from free functions to methods on collections.

• Implement: [T].len() -> int — modules/prelude.md § List [done] (2026-02-10)

  • Rust Tests: Evaluator method dispatch — list len tests
  • Ori Tests: tests/spec/expressions/field_access.ori, tests/spec/lexical/delimiters.ori
  • LLVM Support: LLVM codegen for list len method
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list len method codegen
  • AOT Tests: ori_llvm/tests/aot/collections_ext.rs — test_coll_list_length_empty + 2 variants, test_coll_list_len_alias (4 tests, 0 ignored)

• Implement: [T].is_empty() -> bool — modules/prelude.md § List [done] (2026-02-10)

  • Rust Tests: Evaluator method dispatch — list is_empty tests
  • Ori Tests: tests/spec/traits/core/is_empty.ori — 15+ tests
  • LLVM Support: LLVM codegen for list is_empty method
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — list is_empty method codegen
  • AOT Tests: ori_llvm/tests/aot/collections_ext.rs — test_coll_list_is_empty_true, test_coll_list_is_empty_false (2 tests, 0 ignored)

• Implement: {K: V}.len() -> int — modules/prelude.md § Map [done] (2026-02-10)

  • Rust Tests: Evaluator method dispatch — map len tests
  • Ori Tests: tests/spec/lexical/delimiters.ori — map.len() tests
  • LLVM Support: LLVM codegen for map len method
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — map len method codegen
  • AOT Tests: ori_llvm/tests/aot/collections_ext.rs — test_coll_map_length_basic, test_coll_map_length_one, test_coll_map_len_alias (3 tests, 0 ignored)

• Implement: {K: V}.is_empty() -> bool — modules/prelude.md § Map

  • Rust Tests: ori_eval/src/methods.rs — map is_empty tests
  • Ori Tests: tests/spec/stdlib/map_methods.ori
  • LLVM Support: LLVM codegen for map is_empty method
  • LLVM Rust Tests: ori_llvm/tests/collection_tests.rs — map is_empty method codegen
  • AOT Tests: No AOT coverage yet

• Implement: str.len() -> int — modules/prelude.md § str [done] (2026-02-10)

  • Rust Tests: Evaluator method dispatch — str len tests
  • Ori Tests: tests/spec/expressions/field_access.ori — "hello".len()
  • LLVM Support: LLVM codegen for str len method
  • LLVM Rust Tests: ori_llvm/tests/string_tests.rs — str len method codegen
  • AOT Tests: ori_llvm/tests/aot/strings.rs — test_str_length_basic + 4 variants, test_str_len_alias (6 tests, 0 ignored)

• Implement: str.is_empty() -> bool — modules/prelude.md § str [done] (2026-02-10)

  • Rust Tests: Evaluator method dispatch — str is_empty tests
  • Ori Tests: tests/spec/traits/core/is_empty.ori — "".is_empty(), !"hello".is_empty()
  • LLVM Support: LLVM codegen for str is_empty method
  • LLVM Rust Tests: ori_llvm/tests/string_tests.rs — str is_empty method codegen
  • AOT Tests: ori_llvm/tests/aot/strings.rs — test_str_is_empty_true, test_str_is_empty_false, test_str_is_empty_space (3 tests, 0 ignored)

• Implement: Set<T>.len() -> int — modules/prelude.md § Set [done] (2026-02-25)

  • Rust Tests: ori_eval/src/methods/helpers/mod.rs — set len in TYPECK_BUILTIN_METHODS
  • Ori Tests: tests/spec/types/set_methods/set_methods.ori — set len tests
  • LLVM Support: ori_llvm/src/codegen/arc_emitter/builtins/collections.rs — emit_set_length()
  • AOT Tests: ori_llvm/tests/aot/sets.rs — test_aot_set_length (passing) (2026-03-01)

• Implement: Set<T>.is_empty() -> bool — modules/prelude.md § Set [done] (2026-02-25)

  • Rust Tests: ori_eval/src/methods/helpers/mod.rs — set is_empty in TYPECK_BUILTIN_METHODS
  • Ori Tests: tests/spec/types/set_methods/set_methods.ori — set is_empty tests
  • LLVM Support: ori_llvm/src/codegen/arc_emitter/builtins/collections.rs — emit_set_is_empty()
  • AOT Tests: ori_llvm/tests/aot/sets.rs — test_aot_set_is_empty (passing — check_collect_to_set now unifies element type with expected) (2026-03-01)

• Implement: Set<T>.contains(elem) -> bool — modules/prelude.md § Set [done] (2026-02-25)

  • Evaluator: ori_eval/src/methods/collections.rs — set contains dispatch
  • Ori Tests: tests/spec/types/set_methods/set_methods.ori — set contains tests
  • LLVM Support: ori_llvm/src/codegen/arc_emitter/builtins/collections.rs — emit_set_contains() via ori_set_contains runtime
  • AOT Tests: ori_llvm/tests/aot/sets.rs — test_aot_set_contains (passing) (2026-03-01)

• Implement: Set<T>.insert(elem) -> Set<T> — modules/prelude.md § Set [done] (2026-02-25)

  • Evaluator: ori_eval/src/methods/collections.rs — set insert dispatch
  • Ori Tests: tests/spec/types/set_methods/set_methods.ori — set insert tests
  • LLVM Support: ori_llvm/src/codegen/arc_emitter/builtins/collections.rs — emit_set_insert() via ori_set_insert runtime (sret)
  • AOT Tests: ori_llvm/tests/aot/sets.rs — test_aot_set_insert (passing) (2026-03-01)

• Implement: Set<T>.remove(elem) -> Set<T> — modules/prelude.md § Set [done] (2026-02-25)

  • Evaluator: ori_eval/src/methods/collections.rs — set remove dispatch
  • Ori Tests: tests/spec/types/set_methods/set_methods.ori — set remove tests
  • LLVM Support: ori_llvm/src/codegen/arc_emitter/builtins/collections.rs — emit_set_remove() via ori_set_remove runtime (sret)
  • AOT Tests: ori_llvm/tests/aot/sets.rs — test_aot_set_remove (passing) (2026-03-01)

• Implement: Set<T>.union(other) -> Set<T> — modules/prelude.md § Set [done] (2026-02-25)

  • Evaluator: ori_eval/src/methods/collections.rs — set union dispatch
  • Ori Tests: tests/spec/types/set_methods/set_methods.ori — set union tests
  • LLVM Support: ori_llvm/src/codegen/arc_emitter/builtins/collections.rs — emit_set_union() via ori_set_union runtime (sret)
  • AOT Tests: ori_llvm/tests/aot/sets.rs — test_aot_set_union (passing — lexer fix: reserved-future keywords suppressed in method position) (2026-03-01)

• Implement: Set<T>.intersection(other) -> Set<T> — modules/prelude.md § Set [done] (2026-02-25)

  • Evaluator: ori_eval/src/methods/collections.rs — set intersection dispatch
  • Ori Tests: tests/spec/types/set_methods/set_methods.ori — set intersection tests
  • LLVM Support: ori_llvm/src/codegen/arc_emitter/builtins/collections.rs — emit_set_intersection() via ori_set_intersection runtime (sret)
  • AOT Tests: ori_llvm/tests/aot/sets.rs — test_aot_set_intersection (passing) (2026-03-01)

• Implement: Set<T>.difference(other) -> Set<T> — modules/prelude.md § Set [done] (2026-02-25)

  • Evaluator: ori_eval/src/methods/collections.rs — set difference dispatch
  • Ori Tests: tests/spec/types/set_methods/set_methods.ori — set difference tests
  • LLVM Support: ori_llvm/src/codegen/arc_emitter/builtins/collections.rs — emit_set_difference() via ori_set_difference runtime (sret)
  • AOT Tests: ori_llvm/tests/aot/sets.rs — test_aot_set_difference (passing) (2026-03-01)

• Implement: Set<T>.to_list() -> [T] — modules/prelude.md § Set [done] (2026-02-25)

  • Evaluator: ori_eval/src/methods/collections.rs — set to_list dispatch
  • Ori Tests: tests/spec/types/set_methods/set_methods.ori — set to_list tests
  • LLVM Support: ori_llvm/src/codegen/arc_emitter/builtins/collections.rs — emit_set_to_list() via ori_set_to_list runtime (sret)
  • AOT Tests: ori_llvm/tests/aot/sets.rs — test_aot_set_to_list (passing) (2026-03-01)

7C.5 Comparable Methods (min, max, compare)

Move from free functions to methods on Comparable trait.

• Implement: T.min(other: T) -> T where T: Comparable — modules/prelude.md § Comparable

  • Rust Tests: ori_eval/src/methods.rs — min method tests
  • Ori Tests: tests/spec/stdlib/comparable.ori
  • LLVM Support: LLVM codegen for min method
  • LLVM Rust Tests: ori_llvm/tests/comparison_tests.rs — min method codegen
  • AOT Tests: No AOT coverage yet

• Implement: T.max(other: T) -> T where T: Comparable — modules/prelude.md § Comparable

  • Rust Tests: ori_eval/src/methods.rs — max method tests
  • Ori Tests: tests/spec/stdlib/comparable.ori
  • LLVM Support: LLVM codegen for max method
  • LLVM Rust Tests: ori_llvm/tests/comparison_tests.rs — max method codegen
  • AOT Tests: No AOT coverage yet

• Implement: T.compare(other: T) -> Ordering where T: Comparable — modules/prelude.md § Comparable [done] (2026-02-10)

  • Rust Tests: Evaluator method dispatch — compare method tests
  • Ori Tests: tests/spec/traits/core/comparable.ori — 133 test occurrences
  • LLVM Support: LLVM codegen for compare method
  • LLVM Rust Tests: ori_llvm/tests/comparison_tests.rs — compare method codegen
  • AOT Tests: No AOT coverage yet

7C.6 Iterator Traits

PROPOSAL: proposals/drafts/iterator-traits-proposal.md

Formalize iteration with traits, enabling user types in for loops and generic iteration.

• Implement: Iterator trait

  trait Iterator {
      type Item
      @next (mut self) -> Option<Self.Item>
  }

  • Rust Tests: ori_types/src/check/traits/iterator.rs
  • Ori Tests: tests/spec/traits/iterator.ori
  • LLVM Support: LLVM codegen for Iterator trait
  • LLVM Rust Tests: ori_llvm/tests/iterator_tests.rs — Iterator trait codegen
  • AOT Tests: No AOT coverage yet (formal Iterator trait definition)

• Implement: Iterable trait

  trait Iterable {
      type Item
      @iter (self) -> impl Iterator where Item == Self.Item
  }

  • Rust Tests: ori_types/src/check/traits/iterable.rs
  • Ori Tests: tests/spec/traits/iterable.ori
  • LLVM Support: LLVM codegen for Iterable trait
  • LLVM Rust Tests: ori_llvm/tests/iterator_tests.rs — Iterable trait codegen
  • AOT Tests: No AOT coverage yet (formal Iterable trait definition)

• Implement: Collect trait

  trait Collect<T> {
      @from_iter (iter: impl Iterator where Item == T) -> Self
  }

  • Rust Tests: ori_types/src/check/traits/collect.rs
  • Ori Tests: tests/spec/traits/collect.ori
  • LLVM Support: LLVM codegen for Collect trait
  • LLVM Rust Tests: ori_llvm/tests/iterator_tests.rs — Collect trait codegen
  • AOT Tests: No AOT coverage yet (formal Collect trait definition)

• Implement: Standard Iterable implementations

  • impl<T> [T]: Iterable — list iteration
  • impl<K, V> {K: V}: Iterable — map iteration (yields tuples)
  • impl<T> Set<T>: Iterable — set iteration
  • impl str: Iterable — character iteration
  • impl Range<int>: Iterable — range iteration
  • impl<T> Option<T>: Iterable — zero/one element
  • Ori Tests: tests/spec/stdlib/iterable_impls.ori
  • LLVM Support: LLVM codegen for standard Iterable implementations
  • LLVM Rust Tests: ori_llvm/tests/iterator_tests.rs — Iterable implementations codegen
  • AOT Tests: ori_llvm/tests/aot/iterators.rs — list .iter() (2 tests), range .iter() (2 tests); ori_llvm/tests/aot/collections_ext.rs — map .iter() (2 tests), string .iter() via ori_llvm/tests/aot/strings.rs (3 tests)

• Implement: Standard Collect implementations

  • impl<T> Collect<T> for [T] — collect to list
  • impl<T> Collect<T> for Set<T> — collect to set (LLVM __collect_set implemented 2026-03-01)
  • Ori Tests: tests/spec/stdlib/collect_impls.ori
  • LLVM Support: LLVM codegen for standard Collect implementations — collect-to-list (ori_iter_collect) and collect-to-set (ori_iter_collect_set via __collect_set intercept) both implemented (2026-03-01)
  • LLVM Rust Tests: ori_llvm/tests/iterator_tests.rs — Collect implementations codegen
  • AOT Tests: ori_llvm/tests/aot/iterators.rs — test_list_iter_collect, test_iter_chain_collect (collect to list via .iter().collect())

• Implement: for loop desugaring to .iter() and .next()

  • Rust Tests: ori_eval/src/interpreter/for_loop.rs
  • Ori Tests: tests/spec/control/for_iterator.ori
  • LLVM Support: LLVM codegen for for loop desugaring
  • LLVM Rust Tests: ori_llvm/tests/iterator_tests.rs — for loop desugaring codegen
  • AOT Tests: ori_llvm/tests/aot/iterators.rs — test_for_over_iterator, test_for_over_range_iterator (for-loop over .iter() on lists and ranges)

• Implement: Iterator extension methods

  • map, filter, fold, find, collect, count
  • any, all, take, skip, enumerate, zip, chain
  • Ori Tests: tests/spec/stdlib/iterator_methods.ori
  • LLVM Support: LLVM codegen for iterator extension methods
  • LLVM Rust Tests: ori_llvm/tests/iterator_tests.rs — iterator extension methods codegen
  • AOT Tests: ori_llvm/tests/aot/iterators.rs — 25 tests (0 ignored) covering map, filter, take, skip, count, any, all, find, fold, for_each, collect, zip, chain adapters/consumers via built-in iterator pipeline

7C.7 Debug Trait

PROPOSAL: proposals/drafts/debug-trait-proposal.md

Developer-facing structural output, separate from user-facing Printable.

• Implement: Debug trait

  trait Debug {
      @debug (self) -> str
  }

  • Rust Tests: ori_types/src/check/traits/debug.rs
  • Ori Tests: tests/spec/traits/debug.ori
  • LLVM Support: LLVM codegen for Debug trait
  • LLVM Rust Tests: ori_llvm/tests/debug_tests.rs — Debug trait codegen
  • AOT Tests: No AOT coverage yet

• Implement: #[derive(Debug)] for structs and sum types

  • Rust Tests: ori_types/src/check/derives/debug.rs
  • Ori Tests: tests/spec/traits/debug_derive.ori
  • LLVM Support: LLVM codegen for derive(Debug)
  • LLVM Rust Tests: ori_llvm/tests/debug_tests.rs — derive(Debug) codegen
  • AOT Tests: No AOT coverage yet

• Implement: Standard Debug implementations

  • All primitives: int, float, bool, str, char, byte, void
  • Collections: [T], {K: V}, Set<T> (require T: Debug)
  • Option<T>, Result<T, E> (require inner types Debug)
  • Tuples (require element types Debug)
  • Ori Tests: tests/spec/stdlib/debug_impls.ori
  • LLVM Support: LLVM codegen for standard Debug implementations
  • LLVM Rust Tests: ori_llvm/tests/debug_tests.rs — Debug implementations codegen
  • AOT Tests: No AOT coverage yet

• Implement: String escaping in Debug output

  • "hello".debug() → "\"hello\""
  • '\n'.debug() → "'\\n'"
  • Ori Tests: tests/spec/stdlib/debug_escaping.ori
  • LLVM Support: LLVM codegen for Debug string escaping
  • LLVM Rust Tests: ori_llvm/tests/debug_tests.rs — Debug escaping codegen
  • AOT Tests: No AOT coverage yet

7C.8 Section Completion Checklist

• All items above have all checkboxes marked [ ]
• Re-evaluate against docs/compiler-design/v2/02-design-principles.md
• 80+% test coverage, tests against spec/design
• Run full test suite: ./test-all.sh
• LLVM Support: All LLVM codegen tests pass

Exit Criteria: Collections and iteration working correctly