https://github.com/nwtgck/loop-to-tailrec

Convert a while-loop to a tail-recursive function
https://github.com/nwtgck/loop-to-tailrec

converter loop online tailrec

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Convert a while-loop to a tail-recursive function

• Host: GitHub
• URL: https://github.com/nwtgck/loop-to-tailrec
• Owner: nwtgck
• Created: 2017-03-14T10:23:01.000Z (almost 8 years ago)
• Default Branch: develop
• Last Pushed: 2018-12-20T00:17:35.000Z (about 6 years ago)
• Last Synced: 2024-10-11T15:10:54.575Z (3 months ago)
• Topics: converter, loop, online, tailrec
• Language: JavaScript
• Homepage: https://nwtgck.github.io/loop-to-tailrec
• Size: 785 KB
• Stars: 1
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
loop-to-tailrec

==

Convertor a while-loop to a tail-recursive function

# Page

http://nwtgck.github.io/loop-to-tailrec/

# Demo

![](./demo-images/demo1.gif)

# What is this?

Convert the following format while-loop to a tail-rec function!

# Example1 - Fibonacci

### Input (while-loop)

```scala

def fib ( n: Int ): Int = {

   var i: Int = 0

   var a: Int = 1

   var b: Int = 1

   while(i < n){

     val newI = i+1

     val newA = b

     val newB = a+b

     i = newI

     a = newA

     b = newB

   }

   a

}

```

==>

### Output (tailrec)

```scala

// Scala(tailrec)

def fib ( n: Int ): Int = {

   import scala.annotation.tailrec

   @tailrec

   def _fib( i: Int , a: Int , b: Int ): Int = {

     if(i < n) _fib( i+1 , b , a+b )

     else a

   }

   _fib( 0 , 1 , 1 )

}

```

# Example2 - foldLeft

### Input (while-loop)

```scala

def foldLeft [ E , A ] ( seq: Seq[E] , zero: A , f: (A, E) => A ): A = {

   var accum: A = zero

   var i: Int = 0

   while(i < seq.length){

     val newAccum = f(accum, seq(i))

     val newI = i + 1

     accum = newAccum

     i = newI

   }

   accum

}

```

==>

### Output (tailrec)

```scala

// Scala(tailrec)

def foldLeft [ E , A ] ( seq: Seq[E] , zero: A , f: (A, E) => A ): A = {

   import scala.annotation.tailrec

   @tailrec

   def _foldLeft( accum: A , i: Int ): A = {

     if(i < seq.length) _foldLeft( f(accum, seq(i)) , i + 1 )

     else accum

   }

   _foldLeft( zero , 0 )

}

```

You can access http://nwtgck.github.io/loop-to-tailrec/ and try other examples!