It's Friday night, I'm too tired to do anything useful, but not enough to sleep. I find five small programming katas and I decide that I can start the weekend procrastination already. They are meant to be programmed in the language you feel most comfortable with. Unfortunately, I don't feel comfortable with any language, therefore I used several of them.
PS: Upon closer inspection, probably I should learn Hy.
| f1 = (l) -> | |
| r = 0 | |
| r += e for e in l | |
| r | |
| f2 = (l) -> | |
| r = i = 0 | |
| r += l[i++] while i < l.length | |
| r | |
| f3 = (l) -> l.reduce((a, b) -> a + b) | |
| # because I don't want "cheating" criticism | |
| f4 = (l, a = 0) -> if l[0]? then f4 l[1..], a + l[0] else a | |
| # Bonus (no tail recursion, but JavaScript...): | |
| f5 = (l, a = 0) -> (l[0]? && f5 l[1..], a + l[0]) || a |
| (defn interleave [x y] (mapcat vector x y)) | |
| ;-) or alternatively: | |
| (defn myinterleave [x y] (interleave x y)) |
| import scala.language.postfixOps | |
| object FibApp { | |
| // Why do you want to compute a list with 100 Fibonacci | |
| // numbers when you can have all of them in a collection? | |
| // Of course, Haskell is nicer: | |
| // fibs = 0 : 1 : zipWith (+) fibs (tail fibs) | |
| val fib: Stream[BigInt] = 0 #:: 1 #:: (1 to Int.MaxValue) | |
| .iterator | |
| .map { (n: Int) => fib(n - 1) + fib(n) } | |
| .toStream | |
| def main(args: Array[String]) { | |
| println(fib take 100 toVector) | |
| } | |
| } |
| ponder = lambda n: sum((n[0] - n[i]) / 10 ** i for i in range(1, len(n))) - n[0] | |
| evaluate = lambda s: ponder(list(map(int, s))) | |
| largest = lambda l: ''.join(sorted((str(e) for e in l), key=evaluate)) |
| # yes, I know it's hard to read, but check the JavaScript that it generates! | |
| r for r in (p[-1..][0] for p in ((o.splice i - 1, 0, i; o.join '') for i in [9..1] for o in ( | |
| ['', '+', '-'][c] for c in p for p in (('00000000' + i.toString 3)[-8..] for i in [0..3**8 - 1]) | |
| ))) when eval(r) == 100 |