Программирование на языке Scala/Функции высшего порядка/Ответы
Внешний вид
2.
val mapFun: (String, Char => Char) => String =
(str, fun) => str.foldLeft("")( (acc, el) =>
acc + fun(el)
)
3.
val flatMapFun: (String, Char => String) => String =
(str, fun) => str.foldLeft("")( (acc, el) =>
acc + fun(el)
)
4.
val foreachFun: (String, Char => Unit) => Unit =
(str, fun) => str.foldLeft(())( (_, el) =>
fun(el)
)
5.
val existsFun: (String, Char => Boolean) => Boolean =
(str, fun) => str.foldLeft(false)( (acc, el) =>
fun(el) || acc
)
6.
val filterNotFun: (String, Char => Boolean) => String =
(str, fun) => str.foldLeft("")( (acc, el) =>
if (fun(el))
acc
else
acc + el
)
7.
val distinctByFun: (String, Char => Char) => String =
(str, fun) => str.foldLeft("")( (acc, el) => {
val newEl = fun(el)
if (acc.contains(newEl))
acc
else
acc + newEl
})
8.
val forallFun: (String, Char => Boolean) => Boolean =
(str, fun) => str.foldLeft(true)( (acc, el) =>
fun(el) && acc
)
9.
val countFun: (String, Char => Boolean) => Int =
(str, fun) => str.foldLeft(0)( (acc, el) =>
if (fun(el)) acc + 1
else acc
)
10.
val takeWhileFun: (String, Char => Boolean) => String =
(str, fun) => str.foldLeft(("", false))( (acc, el) => {
val (res, isEnd) = acc
if (isEnd)
(res, isEnd)
else
if (fun(el))
(res + el, false)
else
(res, true)
})._1
11.
val dropWhileFun: (String, Char => Boolean) => String =
(str, fun) => str.foldLeft(("", false))( (acc, el) => {
val (res, isEnd) = acc
if (isEnd)
(res + el, isEnd)
else
if (fun(el))
(res, false)
else
(res + el, true)
})._1
12.
val filterGen: String => (Char => Boolean) =
str =>
if (str.length > 3)
char => char.isDigit
else
char => char.isLetter