I wanted to ensure if I could accomplish this by using reduceLeft rather than foldLeft. I am searching a given number in the List
val included = List(46, 19, 92).foldLeft(false) { (a, i) =>
| if (a) a else (i == 19)
| }
included: Boolean = true
However I want to accomplish the same using reduceLeft, is it possible?
The proper way to do this is
val included = List(46, 19, 92).contains(19)
But if you would insist on using reduceLeft, then you can write:
val included = List(46, 19, 92).reduceLeft { (a, b) =>
if (b == 19) b else a
} == 19
Not directly. The types, as is often the case, are the answer.
reduceLeft has a type sort of like:
List[A] => ((A,A) => A) => A
Given a List of A, and a function which can combine 2 A values into 1 A value, you get a single A value back.
what you could do would be something like:
val a = List(46, 19, 92).reduceLeft { (a, b) =>
if(b == 19) b else a
}
val included = a == 19
Of course, you'd be better served using "contains" for this than either of those options.
contains, not exists, list contains 19 vs list exists (_ == 19)
You can't do it in a simple way. With foldLeft you can define the result type : it's the type of your accumulator so i's the type of the zero element you give as first parameter.
ReduceLeft uses the first element of your collection as the zero element of your accumulator. So the result type will be the same as the elements of the list, Int in your case.
