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ino is membero with the constraint-store-friendly argument order
(`(ino x dom)` reads as "x in dom"). all-distincto checks pairwise
distinctness via nafc + membero on the recursive tail. These two are
enough to express the enumerate-then-filter style of finite-domain
solving:
(fresh (a b c)
(ino a (list 1 2 3)) (ino b (list 1 2 3)) (ino c (list 1 2 3))
(all-distincto (list a b c)))
enumerates all 6 distinct triples from {1, 2, 3}. Full CLP(FD) with
arc-consistency, fd-plus, etc. remains pending under Phase 6 proper.
9 new tests, 237/237 cumulative.
26 lines
1.0 KiB
Plaintext
26 lines
1.0 KiB
Plaintext
;; lib/minikanren/fd.sx — Phase 6 piece A: minimal finite-domain helpers.
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;;
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;; A full CLP(FD) engine (arc consistency, native integer domains, fd-plus
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;; etc.) is Phase 6 proper. For now we expose two small relations layered
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;; on the existing list machinery — they're sufficient for permutation
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;; puzzles, the N-queens-style core of constraint solving:
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;;
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;; (ino x dom) — x is a member of dom (alias for membero with the
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;; constraint-store-friendly argument order).
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;; (all-distincto l) — all elements of l are pairwise distinct.
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;;
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;; all-distincto uses nafc + membero on the tail — it requires the head
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;; element of each recursive step to be ground enough for membero to be
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;; finitary, so order matters: prefer (in x dom) goals BEFORE
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;; (all-distincto (list x ...)) so values get committed first.
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(define ino (fn (x dom) (membero x dom)))
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(define
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all-distincto
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(fn
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(l)
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(conde
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((nullo l))
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((fresh (a d) (conso a d l) (nafc (membero a d)) (all-distincto d))))))
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