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project (clj)
(source)function
(project xrel ks)
Returns a rel of the elements of xrel with only the keys in ks
Examples
clojure
(ns clojure.test-clojure.metadata
(:use clojure.test
[clojure.test-helper :only (eval-in-temp-ns)])
(:require [clojure.set :as set]))
(deftest interaction-of-def-with-metadata
(testing "initial def sets metadata"
(let [v (eval-in-temp-ns
(def ^{:a 1} foo 0)
#'foo)]
(is (= 1 (-> v meta :a)))))
(testing "const vars preserve metadata"
(let [[v1 v2] (eval-in-temp-ns
(def ^:const foo ^:foo [])
(def ^:const bar ^:foo [:bar])
[(meta foo) (meta bar)])]
(is (= {:foo true} v1))
(is (= {:foo true} v2))))
#_(testing "subsequent declare doesn't overwrite metadata"
(let [v (eval-in-temp-ns
(def ^{:b 2} bar 0)
(declare bar)
#'bar)]
(is (= 2 (-> v meta :b))))
(testing "when compiled"
(let [v (eval-in-temp-ns
(def ^{:c 3} bar 0)
(defn declare-bar []
(declare bar))
(declare-bar)
#'bar)]
(is (= 3 (-> v meta :c))))))
(testing "subsequent def with init-expr *does* overwrite metadata"
(let [v (eval-in-temp-ns
(def ^{:d 4} quux 0)
(def quux 1)
#'quux)]
(is (nil? (-> v meta :d))))
(testing "when compiled"
(let [v (eval-in-temp-ns
(def ^{:e 5} quux 0)
(defn def-quux []
(def quux 1))
(def-quux)
#'quux)]
(is (nil? (-> v meta :e))))))
(testing "IllegalArgumentException should not be thrown"
(testing "when defining var whose value is calculated with a primitive fn."
(testing "This case fails without a fix for CLJ-852"
(is (eval-in-temp-ns
(defn foo ^long [^long x] x)
(def x (inc (foo 10))))))
(testing "This case should pass even without a fix for CLJ-852"
(is (eval-in-temp-ns
(defn foo ^long [^long x] x)
(def x (foo (inc 10)))))))))
(deftest fns-preserve-metadata-on-maps
(let [xm {:a 1 :b -7}
x (with-meta {:foo 1 :bar 2} xm)
ym {:c "foo"}
y (with-meta {:baz 4 :guh x} ym)]
(is (= xm (meta (:guh y))))
(is (= xm (meta (reduce #(assoc %1 %2 (inc %2)) x (range 1000)))))
(is (= xm (meta (-> x (dissoc :foo) (dissoc :bar)))))
(let [z (assoc-in y [:guh :la] 18)]
(is (= ym (meta z)))
(is (= xm (meta (:guh z)))))
(let [z (update-in y [:guh :bar] inc)]
(is (= ym (meta z)))
(is (= xm (meta (:guh z)))))
(is (= xm (meta (get-in y [:guh]))))
(is (= xm (meta (into x y))))
(is (= ym (meta (into y x))))
(is (= xm (meta (merge x y))))
(is (= ym (meta (merge y x))))
(is (= xm (meta (merge-with + x y))))
(is (= ym (meta (merge-with + y x))))
(is (= xm (meta (select-keys x [:bar]))))
(is (= xm (meta (set/rename-keys x {:foo :new-foo}))))
;; replace returns a seq when given a set. Can seqs have
;; metadata?
;; TBD: rseq, subseq, and rsubseq returns seqs. If it is even
;; possible to put metadata on a seq, does it make sense that the
;; seqs returned by these functions should have the same metadata
;; as the sorted collection on which they are called?
))
(deftest fns-preserve-metadata-on-vectors
(let [xm {:a 1 :b -7}
x (with-meta [1 2 3] xm)
ym {:c "foo"}
y (with-meta [4 x 6] ym)]
(is (= xm (meta (y 1))))
(is (= xm (meta (assoc x 1 "one"))))
(is (= xm (meta (reduce #(conj %1 %2) x (range 1000)))))
(is (= xm (meta (pop (pop (pop x))))))
(let [z (assoc-in y [1 2] 18)]
(is (= ym (meta z)))
(is (= xm (meta (z 1)))))
(let [z (update-in y [1 2] inc)]
(is (= ym (meta z)))
(is (= xm (meta (z 1)))))
(is (= xm (meta (get-in y [1]))))
(is (= xm (meta (into x y))))
(is (= ym (meta (into y x))))
(is (= xm (meta (replace {2 "two"} x))))
(is (= [1 "two" 3] (replace {2 "two"} x)))
;; TBD: Currently subvec drops metadata. Should it preserve it?
;;(is (= xm (meta (subvec x 2 3))))
;; TBD: rseq returns a seq. If it is even possible to put
;; metadata on a seq, does it make sense that the seqs returned by
;; these functions should have the same metadata as the sorted
;; collection on which they are called?
))
(deftest fns-preserve-metadata-on-sets
;; TBD: Do tests independently for set, hash-set, and sorted-set,
;; perhaps with a loop here.
(let [xm {:a 1 :b -7}
x (with-meta #{1 2 3} xm)
ym {:c "foo"}
y (with-meta #{4 x 6} ym)]
(is (= xm (meta (y #{3 2 1}))))
(is (= xm (meta (reduce #(conj %1 %2) x (range 1000)))))
(is (= xm (meta (-> x (disj 1) (disj 2) (disj 3)))))
(is (= xm (meta (into x y))))
(is (= ym (meta (into y x))))
(is (= xm (meta (set/select even? x))))
(let [cow1m {:what "betsy cow"}
cow1 (with-meta {:name "betsy" :id 33} cow1m)
cow2m {:what "panda cow"}
cow2 (with-meta {:name "panda" :id 34} cow2m)
cowsm {:what "all the cows"}
cows (with-meta #{cow1 cow2} cowsm)
cow-names (set/project cows [:name])
renamed (set/rename cows {:id :number})]
(is (= cowsm (meta cow-names)))
(is (= cow1m (meta (first (filter #(= "betsy" (:name %)) cow-names)))))
(is (= cow2m (meta (first (filter #(= "panda" (:name %)) cow-names)))))
(is (= cowsm (meta renamed)))
(is (= cow1m (meta (first (filter #(= "betsy" (:name %)) renamed)))))
(is (= cow2m (meta (first (filter #(= "panda" (:name %)) renamed))))))
;; replace returns a seq when given a set. Can seqs have
;; metadata?
;; union: Currently returns the metadata of the largest input set.
;; This is an artifact of union's current implementation. I doubt
;; any explicit design decision was made to do so. Like join,
;; there doesn't seem to be much reason to prefer the metadata of
;; one input set over another, if at least two input sets are
;; given, but perhaps defining it to always return a set with the
;; metadata of the first input set would be reasonable?
;; intersection: Returns metadata of the smallest input set.
;; Otherwise similar to union.
;; difference: Seems to always return a set with metadata of first
;; input set. Seems reasonable. Not sure we want to add a test
;; for it, if it is an accident of the current implementation.
;; join, index, map-invert: Currently always returns a value with
;; no metadata. This seems reasonable.
))
clojure
(ns clojure.test-clojure.clojure-set
(:use clojure.test)
(:require [clojure.set :as set]))
(deftest test-project
(are [x y] (= x y)
(set/project compositions [:name]) #{{:name "Art of the Fugue"}
{:name "Requiem"}
{:name "Musical Offering"}}
(set/project compositions [:composer]) #{{:composer "W. A. Mozart"}
{:composer "Giuseppe Verdi"}
{:composer "J. S. Bach"}}
(set/project compositions [:year]) #{{}}
(set/project #{{}} [:name]) #{{}} ))
borkdude/speculative
(ns speculative.set
(:require [clojure.set :as set]
[clojure.spec.alpha :as s]
[speculative.specs :as ss]))
(s/fdef set/project
:args (s/cat :xrel ::rel*
:ks ::ss/sequential)
:ret ::ss/set)