Brummel
d64031c234
Decision 8 ships. Term::App and Term::Do gain tail: bool with serde-default false and skip-when-false serialisation. New typecheck pass verify_tail_positions enforces tail-position rules (Scheme-style propagation through match arms, seq.rhs, let body, lam body). Codegen emits musttail call for marked App calls. Hash invariance verified: only the two migrated print_list defs (list_map_poly.print_list, sort.print_list) changed hashes; all other defs across all 18 fixtures kept bit-identical hashes — confirms the skip-when-false serialisation rule works. Tests 76 -> 79: tail_call_in_non_tail_position_is_rejected, tail_call_in_tail_position_is_accepted, plus an IR-grep e2e test asserting that print_list's recursive call site emits musttail in the lowered IR. Existing 25 e2e tests unchanged in behaviour (map -> [2,3,4], sort -> sorted list). IR evidence at the recursive site: %v7 = musttail call i8 @ail_list_map_poly_print_list(ptr %v6) ret i8 %v7 Two deviations called out in the implementer report and JOURNAL: 1. tail-do uses tail call, not musttail. Cross-type return (runtime helpers return i32, AILang Unit is i8) would have LLVM reject musttail. Path is implemented but not exercised by any current fixture; proper fix is runtime-helper signature change, punted. 2. block_terminated flag in codegen so tail-call emit (musttail call + ret) doesn't get a duplicate trailing ret from surrounding code (match-arm phi, fn-body, lambda thunk). Internal plumbing; required for IR well-formedness. Form (A) productions now at ~30, exactly the constraint-1 budget. Future surface additions need to retire something or explicit-budget-rebalance in DESIGN.md. GC notes from implementer survey land in JOURNAL: - Allocations cluster in lower_ctor; every term-ctor does malloc(8+8n). - Tail recursion does not reduce alloc pressure, only stack. For map-style ctor-blocked recursions, allocation IS the bottleneck. - Per-fn arena is sound only when fn return type contains no boxed ADT. Most current fixtures violate this. Plan 14f: Boehm conservative GC (GC_malloc, -lgc) as a first cut. Single-iter integration, no AST/schema change. Stress test: build a 100k Cons list, observe RSS doesn't blow up. After 14f the language is feature-complete enough for stdlib work (15a). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
232 lines
5.9 KiB
JSON
232 lines
5.9 KiB
JSON
{
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"schema": "ailang/v0",
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"name": "list_map_poly",
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"imports": [],
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"defs": [
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{
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"kind": "type",
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"name": "List",
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"vars": ["a"],
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"doc": "Polymorphic singly-linked list.",
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"ctors": [
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{ "name": "Nil", "fields": [] },
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{
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"name": "Cons",
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"fields": [
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{ "k": "var", "name": "a" },
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{
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"k": "con",
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"name": "List",
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"args": [{ "k": "var", "name": "a" }]
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}
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]
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}
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]
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},
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{
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"kind": "fn",
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"name": "inc",
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"type": {
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"k": "fn",
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"params": [{ "k": "con", "name": "Int" }],
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"ret": { "k": "con", "name": "Int" },
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"effects": []
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},
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"params": ["x"],
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"doc": "Add 1 to an Int.",
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"body": {
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"t": "app",
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"fn": { "t": "var", "name": "+" },
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"args": [
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{ "t": "var", "name": "x" },
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{ "t": "lit", "lit": { "kind": "int", "value": 1 } }
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]
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}
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},
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{
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"kind": "fn",
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"name": "map",
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"type": {
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"k": "forall",
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"vars": ["a", "b"],
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"body": {
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"k": "fn",
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"params": [
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{
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"k": "fn",
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"params": [{ "k": "var", "name": "a" }],
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"ret": { "k": "var", "name": "b" },
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"effects": []
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},
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{
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"k": "con",
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"name": "List",
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"args": [{ "k": "var", "name": "a" }]
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}
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],
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"ret": {
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"k": "con",
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"name": "List",
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"args": [{ "k": "var", "name": "b" }]
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},
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"effects": []
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}
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},
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"params": ["f", "xs"],
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"doc": "Polymorphic map: apply f to every element, recursing on the tail.",
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"body": {
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"t": "match",
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"scrutinee": { "t": "var", "name": "xs" },
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"arms": [
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{
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"pat": { "p": "ctor", "ctor": "Nil", "fields": [] },
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"body": {
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"t": "ctor",
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"type": "List",
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"ctor": "Nil",
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"args": []
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}
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},
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{
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"pat": {
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"p": "ctor",
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"ctor": "Cons",
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"fields": [
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{ "p": "var", "name": "h" },
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{ "p": "var", "name": "t" }
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]
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},
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"body": {
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"t": "ctor",
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"type": "List",
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"ctor": "Cons",
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"args": [
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{
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"t": "app",
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"fn": { "t": "var", "name": "f" },
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"args": [{ "t": "var", "name": "h" }]
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},
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{
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"t": "app",
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"fn": { "t": "var", "name": "map" },
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"args": [
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{ "t": "var", "name": "f" },
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{ "t": "var", "name": "t" }
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]
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}
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]
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}
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}
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]
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}
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},
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{
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"kind": "fn",
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"name": "print_list",
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"type": {
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"k": "fn",
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"params": [
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{
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"k": "con",
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"name": "List",
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"args": [{ "k": "con", "name": "Int" }]
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}
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],
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"ret": { "k": "con", "name": "Unit" },
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"effects": ["IO"]
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},
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"params": ["xs"],
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"doc": "Print each Int on its own line.",
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"body": {
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"t": "match",
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"scrutinee": { "t": "var", "name": "xs" },
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"arms": [
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{
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"pat": { "p": "ctor", "ctor": "Nil", "fields": [] },
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"body": { "t": "lit", "lit": { "kind": "unit" } }
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},
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{
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"pat": {
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"p": "ctor",
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"ctor": "Cons",
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"fields": [
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{ "p": "var", "name": "h" },
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{ "p": "var", "name": "t" }
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]
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},
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"body": {
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"t": "seq",
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"lhs": {
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"t": "do",
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"op": "io/print_int",
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"args": [{ "t": "var", "name": "h" }]
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},
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"rhs": {
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"t": "app",
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"fn": { "t": "var", "name": "print_list" },
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"args": [{ "t": "var", "name": "t" }],
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"tail": true
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}
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}
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}
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]
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}
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},
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{
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"kind": "fn",
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"name": "main",
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"type": {
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"k": "fn",
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"params": [],
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"ret": { "k": "con", "name": "Unit" },
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"effects": ["IO"]
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},
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"params": [],
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"doc": "Map inc over [1,2,3] via polymorphic List, then print: 2,3,4.",
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"body": {
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"t": "app",
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"fn": { "t": "var", "name": "print_list" },
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"args": [
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{
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"t": "app",
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"fn": { "t": "var", "name": "map" },
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"args": [
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{ "t": "var", "name": "inc" },
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{
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"t": "ctor",
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"type": "List",
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"ctor": "Cons",
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"args": [
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{ "t": "lit", "lit": { "kind": "int", "value": 1 } },
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{
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"t": "ctor",
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"type": "List",
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"ctor": "Cons",
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"args": [
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{ "t": "lit", "lit": { "kind": "int", "value": 2 } },
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{
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"t": "ctor",
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"type": "List",
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"ctor": "Cons",
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"args": [
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{ "t": "lit", "lit": { "kind": "int", "value": 3 } },
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{
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"t": "ctor",
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"type": "List",
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"ctor": "Nil",
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"args": []
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}
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]
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}
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]
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}
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]
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}
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]
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}
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]
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}
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}
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]
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}
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