;; 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))))