JuniorTheoryCommon

What does the program print?

SWIFT

let words = ["4", "two", "6"]
let total = words.compactMap { Int($0) }.reduce(0, +)
print(total)

Expecting it not to compile, as with map: map would give [Int?], which reduce(0, +) cannot add up, but compactMap drops nil and returns [Int].
Expecting 12: thinking Int understands number words. Int("two") gives nil, so only 4 and 6 are added.

What does words.map { Int($0) } give, and why can it not be summed with reduce(0, +)?
How would you count the words that are not numbers?

JuniorTheoryCommon

SWIFT

let words = ["4", "two", "6"]
let total = words.compactMap { Int($0) }.reduce(0, +)
print(total)

Expecting it not to compile, as with map: map would give [Int?], which reduce(0, +) cannot add up, but compactMap drops nil and returns [Int].
Expecting 12: thinking Int understands number words. Int("two") gives nil, so only 4 and 6 are added.

What does words.map { Int($0) } give, and why can it not be summed with reduce(0, +)?
How would you count the words that are not numbers?