clojure.core.logic/pred

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Type: macro Added: Clojure unknown Examples: 3 Runnable: 0

([v f])

Check a predicate against the value logic var. Non-relational.

Examples

by qneo on 2015-12-20 . May have evaluation errors. ▶

(run* [q] (pred q symbol?)) () (run* [q] (== q 'x) (pred q symbol?)) (x) (run* [q] (== q 1) (pred q symbol?)) () (run* [q] (== q 1) (pred q number?)) (1)

by hank-lenzi on 2021-12-25 . May have evaluation errors. ▶

Example From PC3 (defn indexed [coll] (map-indexed vector coll)) #'user/indexed (indexed "abcde") ([0 \a] [1 \b] [2 \c] [3 \d] [4 \e]) (defn index-filter [pred coll] (when pred (for [[idx elt] (indexed coll) :when (pred elt)] idx))) (index-filter #{\a \b} "abcdbbb") -> (0 1 4 5 6) ;;; NOTES ;; 'for' used destructuring above. 'for' is not a loop - ;; it's 'list comprehension'. ;; 'pred' is a predicate and a lisp form (i.e., 'keyword') in core.logic ;; - https://clojuredocs.org/clojure.core.logic/pred ;; It's from https://clojuredocs.org/clojure.core.logic ;; and NOT included in core ;; https://github.com/clojure/core.logic ;; for forms accept bindings (':let') , filters (with ':when') ;; and restraints (':when') .

by wactbprot on 2021-12-30 . May have evaluation errors. ▶

(use '[clojure.core.logic :only [run* membero pred]]) ;; The position of the pred expression matters: (run* [q] (pred q keyword?) (membero q [1 :a :b]) (membero q [1 :a :c])) ;; => () (run* [q] (membero q [1 :a :b]) (membero q [1 :a :c]) (pred q keyword?)) ;; => (:a)

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