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Sum and product over a list of ground integers via fold + intarith. Empty list yields the identity (0 for sum, 1 for product). Recurse combines the head with the recursively-computed tail value via pluso-i / *o-i. 9 new tests, 481/481 cumulative.
112 lines
2.5 KiB
Plaintext
112 lines
2.5 KiB
Plaintext
;; lib/minikanren/intarith.sx — fast integer arithmetic via project.
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;;
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;; These are ground-only escapes into host arithmetic. They run at native
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;; speed (host ints) but require their arguments to walk to actual numbers
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;; — they are not relational the way `pluso` (Peano) is. Use them when
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;; the puzzle size makes Peano impractical.
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;;
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;; Naming: `-i` suffix marks "integer-only" goals.
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(define
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pluso-i
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(fn
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(a b c)
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(project
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(a b)
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(if (and (number? a) (number? b)) (== c (+ a b)) fail))))
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(define
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minuso-i
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(fn
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(a b c)
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(project
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(a b)
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(if (and (number? a) (number? b)) (== c (- a b)) fail))))
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(define
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*o-i
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(fn
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(a b c)
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(project
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(a b)
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(if (and (number? a) (number? b)) (== c (* a b)) fail))))
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(define
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lto-i
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(fn
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(a b)
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(project
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(a b)
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(if (and (number? a) (and (number? b) (< a b))) succeed fail))))
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(define
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lteo-i
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(fn
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(a b)
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(project
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(a b)
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(if (and (number? a) (and (number? b) (<= a b))) succeed fail))))
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(define
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neqo-i
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(fn
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(a b)
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(project
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(a b)
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(if (and (number? a) (and (number? b) (not (= a b)))) succeed fail))))
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(define numbero (fn (x) (project (x) (if (number? x) succeed fail))))
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(define stringo (fn (x) (project (x) (if (string? x) succeed fail))))
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(define symbolo (fn (x) (project (x) (if (symbol? x) succeed fail))))
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(define
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even-i
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(fn (n) (project (n) (if (and (number? n) (even? n)) succeed fail))))
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(define
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odd-i
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(fn (n) (project (n) (if (and (number? n) (odd? n)) succeed fail))))
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(define
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sortedo
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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) (== l (list a))))
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((fresh (a b rest mid) (conso a mid l) (conso b rest mid) (lteo-i a b) (sortedo mid))))))
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(define
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mino
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(fn
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(l m)
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(conde
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((fresh (a) (== l (list a)) (== m a)))
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((fresh (a d rest-min) (conso a d l) (mino d rest-min) (conde ((lteo-i a rest-min) (== m a)) ((lto-i rest-min a) (== m rest-min))))))))
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(define
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maxo
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(fn
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(l m)
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(conde
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((fresh (a) (== l (list a)) (== m a)))
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((fresh (a d rest-max) (conso a d l) (maxo d rest-max) (conde ((lteo-i rest-max a) (== m a)) ((lto-i a rest-max) (== m rest-max))))))))
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(define
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sumo
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(fn
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(l total)
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(conde
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((nullo l) (== total 0))
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((fresh (a d rest-sum) (conso a d l) (sumo d rest-sum) (pluso-i a rest-sum total))))))
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(define
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producto
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(fn
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(l total)
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(conde
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((nullo l) (== total 1))
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((fresh (a d rest-prod) (conso a d l) (producto d rest-prod) (*o-i a rest-prod total))))))
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