Brummel
a4be1e58a3
Iteration-discipline milestone, 2 of 3. Strictly additive (nothing tail-related removed; that is it.3). New whole-body pass verify_structural_recursion sibling of verify_tail_positions (DD-1): smaller-set algorithm with implicit candidate inference + unconstrained accumulators (DD-2, foldl=structural), self/mutual via inline ADT-family union-find (DD-3), it.2-only tail==false grandfather. CheckError::NonStructuralRecursion. term_contains_loop (stops at Term::Lam, DD-4) injects Diverge so existing UndeclaredEffect enforces it, no new variant; lam-arrow + LetRec sub-effect sites wired. DESIGN.md Decision 3 synced. Four it.1 loop fixtures gained !Diverge. Two spec-premise boundary defects surfaced + resolved within the additive invariant (corpus clean, check not weakened), recorded as corrected it.3 corpus-migration scope: (1) the "21 tail-app fixtures" grandfather premise under-counts the corpus — no-ADT-candidate counter recursions have no structural position to verify, deferred to it.3; (2) two RC-regression fixtures joined the spec's transitional tail-app grandfather as the other 20 do (RC==GC guards verified still green). cargo test --workspace 622/0; 9 acceptance pins non-vacuous. Specfda9b78, planbc9f512.
42 lines
1.4 KiB
Plaintext
42 lines
1.4 KiB
Plaintext
; Iter it.2 Phase-3 e2e: an it.2-clean structural recursion that
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; actually RUNS. `sum` recurses on the Cons-tail `t` via a plain,
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; non-tail `(app sum t)` — structurally guarded ⇒ the it.2 check
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; classifies it pure + total, so it carries NO `!Diverge` and uses
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; NO `tail-app` marker. This proves the structural-recursion
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; classification is behaviourally sound end-to-end (the "total"
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; verdict is not just a typecheck assertion): build [1,2,3,4,5],
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; sum it structurally, print 15.
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(module struct_rec_sum_e2e
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(data IntList
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(ctor INil)
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(ctor ICons (con Int) (con IntList)))
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(fn sum
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(doc "Structural sum: plain non-tail recursion on the Cons tail. No !Diverge, no tail-app.")
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(type
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(fn-type
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(params (con IntList))
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(ret (con Int))))
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(params xs)
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(body
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(match xs
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(case (pat-ctor INil) 0)
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(case (pat-ctor ICons h t)
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(app + h (app sum t))))))
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(fn main
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(doc "Build [1,2,3,4,5] and print its structural sum. Expected stdout: 15.")
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(type (fn-type (params) (ret (con Unit)) (effects IO)))
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(params)
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(body
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(app print
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(app sum
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(term-ctor IntList ICons 1
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(term-ctor IntList ICons 2
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(term-ctor IntList ICons 3
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(term-ctor IntList ICons 4
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(term-ctor IntList ICons 5
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(term-ctor IntList INil)))))))))))
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