clojure.core/dorun

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Type: function Added: Clojure 1.0 Examples: 4 Runnable: 1

([coll] [n coll])

When lazy sequences are produced via functions that have side effects, any effects other than those needed to produce the first element in the seq do not occur until the seq is consumed. dorun can be used to force any effects. Walks through the successive nexts of the seq, does not retain the head and returns nil.

Examples

by gstamp on 2010-08-06 . May have evaluation errors. ▶

(dorun 5 (repeatedly #(println "hi"))) hi hi hi hi hi hi nil

by devn on 2012-04-26 ▶

(let [x (atom 0)] (dorun (take 10 (repeatedly #(swap! x inc)))) @x) 10

by john.r.woodward on 2012-07-24 . May have evaluation errors. ▶

(dorun (map #(println "hi" %) ["mum" "dad" "sister"])) hi mum hi dad hi sister nil

by gdeer81 on 2015-07-07 . May have evaluation errors. ▶

;;map a function which makes database calls over a vector of values (map #(db/insert :person {:name %}) ["Fred" "Ethel" "Lucy" "Ricardo"]) JdbcSQLException The object is already closed [90007-170] org.h2.message.DbE xception.getJdbcSQLException (DbException.java:329) ;;database connection was closed before we got a chance to do our transactions ;;lets wrap it in dorun (dorun (map #(db/insert :person {:name %}) ["Fred" "Ethel" "Lucy" "Ricardo"])) DEBUG :db insert into person values name = 'Fred' DEBUG :db insert into person values name = 'Ethel' DEBUG :db insert into person values name = 'Lucy' DEBUG :db insert into person values name = 'Ricardo' nil

Note by finalfantasia

clojure.core/run! can take the place of (dorun (map ...)).

See also

• clojure.core/doall (0)
• clojure.core/doseq (9)
• clojure.core/run! (1)

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