Avoid force-unwrapped optionals

[Dominik Kapusta]

Apologies if that's stating the obvious, and it probably is, but you asked for it :)

advent-swift/Sources/advent2019/day1.swift

Line 20 in c1bae58

 return input.map { Int($0)! } 

The alternative that wouldn't crash when given rubbish input is to use compactMap that takes a closure returning an optional, and filters nil values:

return input.compactMap { Int($0) }

[Jerzy Chałupski]

OK, but in this case I'm parsing the input from file, so crashing is probably preferable to silently dropping the problematic input lines. What would be the idiomatic way of handling such scenario?

[Dominik Kapusta]

In that case you could use guard statement:

return input.map { stringValue in
    guard let intValue = Int(stringValue) else {
        fatalError("oh well")
    }
    return intValue
}

Note that $0-notation is generally discouraged for closures longer than 1 line.