[coll] -> coll [n coll] -> coll
Walks the first
n of a sequence, or its full length if
n is not provided forcing elements of the sequence to be computed. Returns the head of the sequence as if no elements had been consumed, however the first
n will have been forced and will reside in memory.
A wrapper around clj::clojure.core/dorun which returns the head of the forced
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. See clj::clojure.core/map for some discussion of this behavior.
doall can be used to force any effects to occur by causing sequence elements to be computed.