Term::If was semantically a subset of Term::Match on Bool. Per
CLAUDE.md the language must contain no redundancies; two AST nodes
for the same operation produces an authoring decision with no
semantic content and a duplicate codegen path. Removed.
Migration shape (applied to sum, sort, max3 fixtures):
(if c a b) -> (match c (case (lit-bool true) a) (case _ b))
No schema version bump (per user direction): no third-party consumes
ailang/v0, so version ceremony is pure overhead. Edited AST and
fixtures in place; pinned hashes in hash.rs updated.
Implementer deviation, called out and justified: a tightly-scoped
lower_bool_match helper (~95 LOC) was needed in codegen because
the existing match path rejects i1 scrutinees and Pattern::Lit.
Helper accepts only the canonical two-arm migration shape, errors
on anything else, emits the same br/phi IR Term::If used to. No
generalisation of the ADT-match codegen.
Diff: 13 files, +286/-221 (net +65 LOC). AST got smaller
(one variant gone), form-(A) got smaller (one production gone),
typecheck got smaller (one branch gone). Codegen got slightly
larger by the bool-match helper.
Hash deltas: sum.sum, sort.insert, max3.max, max3.max3 changed.
All other defs (e.g. sum.main, sort.IntList, sort.sort,
sort.print_list, max3.main) kept bit-identical hashes — confirms
canonical-JSON byte format intact.
Verification: 76/76 tests green; sum->55, max3->17, sort->[1,1,2,
3,3,4,5,5,5,6,9] (identical to pre-migration). cargo doc 0 warnings.
Tail-call survey by implementer (informs 14e): print_list
recursions are already in tail position (rhs of seq inside match
arm); map/sort/insert recursions are NOT (constructor-blocked
inside Cons applications). 14e annotation will benefit terminal
recursions; ctor-blocked ones need accumulator-form rewrites in
source, not a compiler-side transform.
Decision 7 added to DESIGN.md. JOURNAL entry has the language-
completion sequence (14d done, 14e tail-calls, 14f GC, 15a stdlib).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
examples/sort.ail.json: insertion sort over IntList. Defines `insert
:: Int -> IntList -> IntList` and `sort :: IntList -> IntList`
recursively, plus print_list using Iter 10's seq. Sorts an 11-element
input and prints `1 1 2 3 3 4 5 5 5 6 9` one-per-line.
Validates that the language handles deeper ADT recursion + branching
(if + <=) + ctor construction + IO sequencing without surprises.
Wrote, typechecked, ran first try.
The Iter 11 plan called for polymorphism, but on reflection the right
move was one more validation cycle before disturbing the pipeline.
Polymorphism is now queued explicitly as Iter 12 (12a typechecker
substitution, 12b codegen monomorphisation, 12c docs + generic
example).
Tests: 52 green (was 51). New e2e `insertion_sort_orders_list`.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Brummel