July 2016
Beginner to intermediate
776 pages
17h 26m
Korean
Content preview from 프로그래밍 스칼라: 실용적인 스칼라 활용법을 익히는 가장 확실한 실전 바이블 (2.11.x 버전 기반)
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341
7
장
for 내장
mai
n
에 있는 ) 두
for
내장의 각 반복에는 상태가 없다. 따라서 메모리에 한 번에 한 줄 이상을
유지할 필요가 없다.
실제로
scala
.
collection
.
Iterator
(
http
://
bit
.
ly
/
1q92kQc
)의
toSeq
를 호출하면
scala
.
collection
.
TraversableOnce
(
http
://
bit
.
ly
/
1pbs2bK
)에 있는 기본 구현은
Stream
(
http
://
bit
.
ly
/
1toy0G5
)을 반환한다. 반면
Iterator
의 서브클래스인 다른 타입들은 엄격한
컬렉션을 반환할 것이다.
7.2
for
내장: 내부 동작
for
내장 문법은 실제로는 컬렉션 메서드인
foreach
,
map
,
flatMap
,
withFilter
를 호출하는
것에 대한 구문상의 편의일 뿐이다.
이런 메서드를 호출하는 다른 방법을 제공하는 이유가 뭘까? 단순하지 않은 연쇄 호출의 경우,
여러
API
함수를 호출하는 것보다
for
내장이 훨씬 읽기 쉽고 쓰기 쉽기 때문이다.
withFilter
는 우리가 이미 살펴본
filter
메서드처럼 원소를 걸러내는 용도로만 사용된다.
스칼라는
withFilter
가 없는 경우
filter
를 사용할 것이다 (이때 경고를 출력한다). 하지만
filter
와 달리
withFilter
는 컬렉션을 만들어내지 않는다. ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.