Brummel
747b7cd05c
Dogfood payoff for parameterised ADTs (13a/b/c). Adds the first
program to nest a nullary ctor of a parameterised ADT inside a
parent ctor (Cons(Int, Nil)) and to call a polymorphic recursive
higher-order fn over a recursive parameterised ADT.
Fixture (examples/list_map_poly.ail.json):
- data List a = Nil | Cons a (List a)
- inc : (Int) -> Int = \x. x + 1
- map : forall a b. ((a) -> b, List<a>) -> List<b>
recursive, instantiated at (Int, Int)
- print_list : (List<Int>) -> Unit !{IO}, recursive
- main builds [1,2,3], maps inc, prints each: "2", "3", "4"
E2E test list_map_poly_inc_then_prints in crates/ail/tests/e2e.rs.
Bug fixed (crates/ailang-codegen/src/lib.rs, +30/-9):
synth_arg_type used Type::unit() as placeholder for ADT type
vars that the ctor's args couldn't pin (Nil for List<a>).
Inside Cons(Int, Nil), unify_for_subst then bound a=Int from
the head and collided with a=Unit from the tail. Replaced the
placeholder with a synth-only wildcard Type::Var{name:"$u"}
mirroring the checker's $m metavar convention; unify_for_subst
short-circuits on $u-prefixed arg-side vars (accept without
binding, let a sibling pin the var).
No schema or API change. No new variant. Tester's recursion
hypothesis was refuted by debugger via a non-recursive
Cons(7, Nil) repro before the fix landed.
Tests: 25/25 e2e (was 24). All Iter 12/13 regressions green.
cargo doc --no-deps zero warnings (workspace invariant from
13d/e/f preserved).
Three-agent flow (tester -> debugger, no implementer needed
since the fix was inside debugger's <50 LOC scope). Process
note in JOURNAL.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
231 lines
5.9 KiB
JSON
231 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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}
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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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