let Create a new scope
1 2 3 4 (let (recur (into (set [part (matching-part part)]))))
loop 1 2 3 4 5 6 7 8 9 10 11 (loop 0 ] (println (str "Iteration " iteration)) (if > 3 ) (println "Goodbye!" ) (recur inc
cond 1 2 3 4 5 6 7 (defn pos-neg-or-zero "Determines whether or not n is positive, negative, or zero" [n] (cond (< 0 ) "negative" (> 0 ) "positive" :else "zero" ))
Regular Expressions re-find
Better Symmetrizer with reduce 1 2 3 4 5 6 like this (+ + + 1 2 ) 3 ) 4 ) you can (reduce 15 [1 2 3 4 ])
into repeat 1 2 3 4 5 (def websites (into repeat 1000 "codewars" )) )
seq Returns a seq on the collection. If the collection is
1 2 3 4 5 6 7 8 (seq 1 2 3 )) (seq 1 2 3 ]) (seq 1 2 3 }) (seq :name "Bill Compton" :occupation "Dead mopey guy" })
map 1 2 3 4 (map inc [1 2 3]); => (2 3 4) (map str ["a" "b" "c"] ["A" "B" "C"]); => ("aA" "bB" "cC")
reduce take 1 2 3 4 (take 3 [1 2 3 4 5 6 7 8 9 10]) ; => (1 2 3) (drop 3 [1 2 3 4 5 6 7 8 9 10]) ; => (4 5 6 7 8 9 10)
take-while 1 2 3 4 5 (take-while #(< (:month %) 3) food-journal) ; => ({:month 1 :day 1 :human 5.3 :critter 2.3} {:month 1 :day 2 :human 5.1 :critter 2.0} {:month 2 :day 1 :human 4.9 :critter 2.1} {:month 2 :day 2 :human 5.0 :critter 2.5})
drop-while 1 2 3 4 5 (drop-while #(< (:month %) 3) food-journal) ; => ({:month 3 :day 1 :human 4.2 :critter 3.3} {:month 3 :day 2 :human 4.0 :critter 3.8} {:month 4 :day 1 :human 3.7 :critter 3.9} {:month 4 :day 2 :human 3.7 :critter 3.6})
filter 1 2 3 4 5 6 (filter #(< (:human %) 5) food-journal) ; => ({:month 2 :day 1 :human 4.9 :critter 2.1} {:month 3 :day 1 :human 4.2 :critter 3.3} {:month 3 :day 2 :human 4.0 :critter 3.8} {:month 4 :day 1 :human 3.7 :critter 3.9} {:month 4 :day 2 :human 3.7 :critter 3.6})
some a collection contains any values that test true for a predicate function
1 2 3 4 (some #(> :critter %) 5 ) food-journal) (some #(> :critter %) 3 ) food-journal)
sort and sort-by 1 2 3 4 (sort [3 1 2]) ; (1 2 3) (sort-by count ["aaa" "c" "bb"]) ; => ("c" "bb" "aaa")
concat 1 2 (cancat [1 2] [3 4]) ; => (1 2 3 4)
lazy-seq A lazy seq is a seq whose members aren’t computed until you try to access them.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 (def vampire-database {0 {:makes-blood-puns? false, :has-pulse? true :name "McFishwich"} 1 {:makes-blood-puns? false, :has-pulse? true :name "McMackson"} 2 {:makes-blood-puns? true, :has-pulse? false :name "Damon Salvatore"} 3 {:makes-blood-puns? true, :has-pulse? true :name "Mickey Mouse"}}) (defn vampire-related-details [social-security-number] (Thread/sleep 1000) (get vampire-database social-security-number)) (defn vampire? [record] (and (:makes-blood-puns? record) (not (:has-pulse? Record)) record)) (defn identify-vampire [social-security-numbers] (first (filter vampire? (map vampire-related-details social-security-numbers))))
Infinite Sequences repeat 1 2 3 4 5 6 7 8 9 10 (concat (take 8 (repeat "na")) ["Batman!"]) ; => ("na" "na" "na" "na" "na" "na" "na" "na" "Batman!") (take 3 (repeatedly (fn [] (rand-int 10)))) ; => (1 4 0) (defn even-numbers ([] (even-numbers 0)) ([n] (cons n (lazy-seq (even-numbers (+ n 2)))))) (take 10 (even-numbers)); => (0 2 4 6 8 10 12 14 16 18) (cons 0 '(2 4 6)); => (0 2 4 6)
The Collection Abstraction The collection abstraction is closely related to the sequence abstraction.
empty 1 2 3 4 (empty? []) ; => true (empty? ["no!"]) ; => false
into 1 2 3 4 5 (map identity {:sunlight-reaction "Glitter!"}) ; => ([:sunlight-reaction "Glitter!"]) (into {} (map identity {:sunlight-reaction "Glitter!"})) ; => {:sunlight-reaction "Glitter!"}
conj 1 2 (conj [0] [1]) ; => [0 [1]]
Function Functions apply 1 2 3 4 5 6 7 8 (max 0 1 2) ; => 2 (max [0 1 2]) ; => [0 1 2] (apply max [0 1 2]) ; => 2
partial 像一个闭包一样保存着环境
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 (def add10 (partial + 10)) (add10 3) ; => 13 (add10 5) ; => 15 (def add-missing-elements (partial conj ["water" "earth" "air"])) (add-missing-elements "unobtainium" "adamantium") ; => ["water" "earth" "air" "unobtainium" "adamantium"] (defn lousy-logger [log-level message] (condp = log-level :warn (clojure.string/lower-case message) :emergency (clojure.string/upper-case message))) (def warn (partial lousy-logger :warn)) (warn "Red light ahead"); => "red light ahead"
slurp 读取文件的函数
