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Squash merge of 76 commits from loops/minikanren. Adds lib/minikanren/ — a complete miniKanren-on-SX implementation built on top of lib/guest/match.sx, validating the lib-guest unify-and-match kit as intended. Modules (20 .sx files, ~1700 LOC): unify, stream, goals, fresh, conde, condu, conda, run, relations, peano, intarith, project, nafc, matche, fd, queens, defrel, clpfd, tabling Phases 1–5 fully done (core miniKanren API, all classic relations, matche, conda, project, nafc). Phase 6 — native CLP(FD): domain primitives, fd-in / fd-eq / fd-neq / fd-lt / fd-lte / fd-plus / fd-times / fd-distinct / fd-label, with constraint reactivation iterating to fixed point. N-queens via FD: 4-queens 2 solutions, 5-queens 10 solutions (vs naive timeout past N=4). Phase 7 — naive ground-arg tabling: table-1 / table-2 / table-3. Fibonacci canary: tab-fib(25) = 75025 in seconds, naive fib(25) times out at 60s. Ackermann via table-3: A(3,3) = 61. 71 test files, 644+ tests passing across the suite. Producer/consumer SLG (cyclic patho, mutual recursion) deferred — research-grade work. The lib-guest validation experiment is conclusive: lib/minikanren/ unify.sx adds ~50 lines of local logic (custom cfg, deep walk*, fresh counter) over lib/guest/match.sx's ~100-line kit. The kit earns its keep ~3× by line count.
67 lines
2.0 KiB
Plaintext
67 lines
2.0 KiB
Plaintext
;; lib/minikanren/stream.sx — Phase 2 piece A: lazy streams of substitutions.
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;;
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;; SX has no improper pairs (cons requires a list cdr), so we use a
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;; tagged stream-cell shape for mature stream elements:
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;;
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;; stream ::= mzero empty (the SX empty list)
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;; | (:s HEAD TAIL) mature cell, TAIL is a stream
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;; | thunk (fn () ...) → stream when forced
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;;
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;; HEAD is a substitution dict. TAIL is again a stream (possibly a thunk),
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;; which is what gives us laziness — mk-mplus can return a mature head with
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;; a thunk in the tail, deferring the rest of the search.
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(define mzero (list))
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(define s-cons (fn (h t) (list :s h t)))
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(define
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s-cons?
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(fn (s) (and (list? s) (not (empty? s)) (= (first s) :s))))
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(define s-car (fn (s) (nth s 1)))
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(define s-cdr (fn (s) (nth s 2)))
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(define unit (fn (s) (s-cons s mzero)))
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(define stream-pause? (fn (s) (and (not (list? s)) (callable? s))))
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;; mk-mplus — interleave two streams. If s1 is paused we suspend and
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;; swap (Reasoned Schemer "interleave"); otherwise mature-cons head with
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;; mk-mplus of the rest.
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(define
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mk-mplus
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(fn
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(s1 s2)
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(cond
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((empty? s1) s2)
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((stream-pause? s1) (fn () (mk-mplus s2 (s1))))
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(:else (s-cons (s-car s1) (mk-mplus (s-cdr s1) s2))))))
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;; mk-bind — apply goal g to every substitution in stream s, mk-mplus-ing.
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(define
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mk-bind
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(fn
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(s g)
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(cond
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((empty? s) mzero)
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((stream-pause? s) (fn () (mk-bind (s) g)))
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(:else (mk-mplus (g (s-car s)) (mk-bind (s-cdr s) g))))))
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;; stream-take — force up to n results out of a (possibly lazy) stream
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;; into a flat SX list of substitutions. n = -1 means take all.
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(define
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stream-take
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(fn
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(n s)
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(cond
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((= n 0) (list))
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((empty? s) (list))
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((stream-pause? s) (stream-take n (s)))
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(:else
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(cons
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(s-car s)
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(stream-take
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(if (= n -1) -1 (- n 1))
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(s-cdr s)))))))
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