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rose-ash/lib/minikanren/intarith.sx
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mk: sortedo — list is non-decreasing (intarith)
Three conde clauses: empty list / singleton list / two-or-more (where
the first two satisfy lteo-i and the rest is recursively sorted). Uses
ground-only integer comparison (intarith), so the input list must
walk to ground integers.

7 new tests, 463/463 cumulative.
2026-05-08 12:10:52 +00:00

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;; lib/minikanren/intarith.sx — fast integer arithmetic via project.
;;
;; These are ground-only escapes into host arithmetic. They run at native
;; speed (host ints) but require their arguments to walk to actual numbers
;; — they are not relational the way `pluso` (Peano) is. Use them when
;; the puzzle size makes Peano impractical.
;;
;; Naming: `-i` suffix marks "integer-only" goals.
(define
pluso-i
(fn
(a b c)
(project
(a b)
(if (and (number? a) (number? b)) (== c (+ a b)) fail))))
(define
minuso-i
(fn
(a b c)
(project
(a b)
(if (and (number? a) (number? b)) (== c (- a b)) fail))))
(define
*o-i
(fn
(a b c)
(project
(a b)
(if (and (number? a) (number? b)) (== c (* a b)) fail))))
(define
lto-i
(fn
(a b)
(project
(a b)
(if (and (number? a) (and (number? b) (< a b))) succeed fail))))
(define
lteo-i
(fn
(a b)
(project
(a b)
(if (and (number? a) (and (number? b) (<= a b))) succeed fail))))
(define
neqo-i
(fn
(a b)
(project
(a b)
(if (and (number? a) (and (number? b) (not (= a b)))) succeed fail))))
(define numbero (fn (x) (project (x) (if (number? x) succeed fail))))
(define stringo (fn (x) (project (x) (if (string? x) succeed fail))))
(define symbolo (fn (x) (project (x) (if (symbol? x) succeed fail))))
(define
even-i
(fn (n) (project (n) (if (and (number? n) (even? n)) succeed fail))))
(define
odd-i
(fn (n) (project (n) (if (and (number? n) (odd? n)) succeed fail))))
(define
sortedo
(fn
(l)
(conde
((nullo l))
((fresh (a) (== l (list a))))
((fresh (a b rest mid) (conso a mid l) (conso b rest mid) (lteo-i a b) (sortedo mid))))))