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| // What are nested and curried functions? How do you use them in Swift? | |
| // nesting/currying allows piping function calls together like fn(1)(2)(3) | |
| // multiple functions, requires fnA(1) + fnB(2) + fnC(3) syntax | |
| func daysToSeconds(days:Int)->Int { | |
| return days * 24 * 60 * 60 | |
| } | |
| func hoursToSeconds(hours:Int)->Int { | |
| return hours * 60 * 60 | |
| } | |
| func minutesToSeconds(minutes:Int)->Int { | |
| return minutes * 60 | |
| } | |
| // just call each function and add the results | |
| let s1 = daysToSeconds(5) + hoursToSeconds(4) + minutesToSeconds(35) // 448,500 | |
| // nested functions | |
| // this is a function that returns a function that returns a function | |
| // allows the syntax fn(1)(2)(3), but is somewhat verbose | |
| func daysHoursMinutesToSeconds(days:Int)->(Int -> (Int -> Int)) { | |
| func hours(hours:Int)->(Int -> Int) { | |
| func minutes(minutes:Int)->Int { | |
| // the nested functions have access to the wrapped parameters | |
| return days * 24 * 60 * 60 + hours * 60 * 60 + minutes * 60 | |
| } | |
| return minutes | |
| } | |
| return hours | |
| } | |
| // calls can now be nested, calling on the returned function directly | |
| let s2 = daysHoursMinutesToSeconds(5)(4)(35) // 448,500 | |
| // curried functions | |
| // functionally equivilent to the nested version above, allows fn(1)(2)(3) | |
| func toSeconds(#days:Int)(hours:Int)(minutes:Int)->Int { | |
| return days * 24 * 60 * 60 + hours * 60 * 60 + minutes * 60 | |
| } | |
| let s3 = toSeconds(days:5)(hours:4)(minutes:35) // 448,500 | |
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