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  1. Practice
  2. Functional Programming
  3. Introduction
  4. Hello World N Times
  5. Discussions

Hello World N Times

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  • alsuga + 4 comments

    Lang: Haskell
    I'm learning haskell, if someone have a suggestion or a correction please let me know

    hello_worlds 1 = putStrLn "Hello World"
hello_worlds n = do
        putStrLn "Hello World" 
        hello_worlds (n - 1)

main = do
   n <- readLn :: IO Int
   hello_worlds n
    • FengkieJ + 1 comment

      doing loop by recursion! cool man, you done it right. there's more elegant way to solve it, but your solution shows how a fp supposed to be written.

      • kaushala + 1 comment

        Any way to loop other than this? Thanks in advance

        • SF
          sfelde21 + 0 comments

          @kaushala nope

    • zefciu + 0 comments

      Maybe more elegant and DRY:

      hello_worlds 0 = return ()
    • SF
      sfelde21 + 1 comment

      what does this line do?

      hello_worlds 1 = putStrLn "Hello World"
      • aleksei_maide + 0 comments

        I wasn't sure either (new to haskell), but apparently it's a stop condition. (If the input to the function is 1 then it simply does the following: putStrLn "Hello World")

    • KR
      Hertzz + 1 comment

      I've had many issues with this mostly bc of the function getManyLines that editor provides and I've ended up cutting it down to basicly your hello_worlds. It prints hello world ten times, and the editor is still saying the outpust is wrong. Also, shouldn't haskell functions be defined for all possible inputs? Does anybody have good sources for learning Haskell? turns out to be much more difficult then object oriented Langs

      • alsuga + 0 comments

        http://learnyouahaskell.com/

  • christopher_lil1 + 1 comment

    My version in Haskell:

    hello_worlds n = mapM_ putStrLn $ replicate n "Hello World"

    • NR
      nitinradkeirctc + 0 comments

      mine is same hello_worlds n = mapM_ putStrLn (take n (repeat "Hello World"))

  • JZ
    xiang19950505 + 0 comments

    My version in Haskell:

    import Control.Monad (replicateM_)

hello_worlds :: Int -> IO ()
hello_worlds n = replicateM_ n $ putStrLn "Hello World"

  • rorick + 1 comment

    Bad problem description for Clojure.

    Description states to copy template and fill blank: (fn[n]___________________________)

    But prepared caller part of solution is (hello_word_n_times n) and is not editable. It will not compile if one copies template and fills blanks. Temlate must be (defn hello_word_n_times [n]___________________________) or (def hello_word_n_times (fn[n]___________________________)).

    BTW, there's also a misspelling in calling part that cannot be edited: word instead of wor**l**d.

    I'm starting to suspect, that guys from Hackerrank do not really like Clojurists) Another surprise waiting Hackerrank student on his way of learning FP in Clojure is when his tested and submitted solution will fail with compile error. That's most likely because of version mismatch. Described environment is Clojure 1.9 and that is what anyone expects, but in reality it is ancient Clojure 1.6.

    • Y
      Katajam + 0 comments

      Thank you. I was trying hard to figure out the compile error as a person who never code in this language before...

  • antonio_net + 0 comments

    There is my Clojure solution:

    (defn hello_word_n_times[n]
    (if (not= n 0) 
        (do
            (println "Hello World")
            (recur (dec n)))))

  • S
    Sri1998 + 1 comment

    What's the problem with this racket code (not compiling)? Works fine in Dr Racket compiler.

    (define (hpr x)
    (if (= x 1) 
      "Hello World"
      (string-append "Hello World \n " (hpr (- x 1)))))

(let ([n (read)])
  (printf "~a~%" (hpr n)))
    • R
      ravi_andrew_baj1 + 0 comments

      Yeah, this code seems perfect but I think it needs attention as it refuses to run as it usually must. This is the error message:

      Compile time error Compile Message load-handler: expected a module' declaration forsolution' in #, but found something else compilation context...: solution.rkt context...: /usr/share/racket/collects/syntax/modcode.rkt:62:2: reader /usr/share/racket/collects/syntax/modcode.rkt:279:5: compile-one /usr/share/racket/collects/compiler/cm.rkt:363:0: compile-zo* /usr/share/racket/collects/compiler/cm.rkt:572:26 /usr/share/racket/collects/compiler/cm.rkt:564:42 /usr/share/racket/collects/compiler/cm.rkt:644:2: do-check /usr/share/racket/collects/compiler/cm.rkt:737:4 /usr/share/racket/pkgs/compiler-lib/compiler/commands/make.rkt:81:8: for-loop /usr/share/racket/pkgs/compiler-lib/compiler/commands/make.rkt: [running body] /usr/share/racket/collects/raco/raco.rkt: [running body] /usr/share/racket/collects/raco/main.rkt: [running body] Exit Status 255

  • xxiane + 3 comments

    I'm getting a weird error message:

    Solution.scala:16: error: not found: value f
  f(n)
  ^
one error found

    Here's everything I have (Scala):

    object Solution extends App {
    object Solution {

        def main(args: Array[String]) {
            val sc = new java.util.Scanner (System.in);
            var n = sc.nextInt();


            def f(n: Int) = {
                for(i <- 0 until n) {
                    println("Hello World");
                }
            }
        }

    }
    var n = scala.io.StdIn.readInt
    f(n)
}

    Am I just putting the f(n) in the wrong place?

    • ObaidGill + 0 comments
      [deleted]
    • ObaidGill + 0 comments
      object Solution {

    def main(args: Array[String]) {
        val sc = new java.util.Scanner (System.in);
        var n = sc.nextInt();
    }
}

def f(n: Int) : Unit = {
    for (i <- 1 to n) {
      println("Hello World")  
    }
        
}
    • RS
      singh_r1115 + 1 comment

      keep the function f directly in the pane remove all other code like below

      def f(n:Int):Unit = {
        for(i <- 1 to n)
          Console println "Hello World"
    }
      • PitrDubovich + 1 comment

        Or, using foreach:

        def f(n:Int):Unit = {
        (1 to n).foreach (_ => println("Hello World")) 
    }
        • binoyyj + 1 comment

          Can someone please explain this code? I'm new to Scala.

          • PitrDubovich + 1 comment

            In the code above:

            def f(n:Int):Unit = {
        (1 to n).foreach (_ => println("Hello World")) 
}

            We define a function, f, which takes one integer argument, n, and returns Unit which is sort of like void in Java (because we don't need to return anything in particular, as the purpose of the function is to print the output "Hello World", not return it).

            The function works by calling the to method of the Int class (1 to n) which creates a Range. Range has a method forEach, which applies a function to each element in the range.

            The function applied to each element of the Range 1..n is this part of the code: _ => println("Hello World"). The Range class calls this function over and over again, each time passing in one of the values from 1 to n (so: 1, then 2, then 3, etc), but because we don't need to know which element we are currently on just to print Hello World, we ignore that argument, which is why we name it underscore (_).

            • binoyyj + 0 comments

              Understood. Thank you for the detailed explaination!

  • knowsuchagency + 0 comments

    F#

    Man, I love this language.

    open System

let rec printHello n = 
    printfn "Hello World"
    match n with
    | 0 | 1 -> 0
    | _ -> printHello (n-1)
    
[<EntryPoint>]
let main args = 
    let n = Console.ReadLine() |> int
    printHello n

  • sundhar010 + 0 comments

    My Elixir solution

    defmodule Solution do
    def hello(a) do
        if a>0 do
          IO.puts "Hello World"
          hello(a-1)
        end
     end
end

n = IO.gets("") |> String.strip |> String.to_integer
Solution.hello n

  • Sg_Sridhar + 1 comment

    Lang: Clojure

    Why is this not working??

    (fn [n] (for [x (repeat n "Hello World")] (println x)))
    • GB
      gcbeltramini + 0 comments

      Use the function dotimes: https://clojuredocs.org/clojure.core/dotimes

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