From: Logan Capaldo <logancapaldo@...>
Date: 2005-12-19T15:31:44+09:00
Subject: Re: ruby beats them all


On Dec 15, 2005, at 8:46 PM, Matt O'Connor wrote:

> jwesley wrote:
>> If Ruby properly handled tail-recursion, then the "accumulator  
>> passing"
>> style work for any number:
>> def fib n
>>   fib_helper( n, 1, 1)
>> end
>> def fib_helper n, next_val, val
>>   n < 1 ? val : fib_helper( n-1, next_val + val, next_val)
>> end
>> the above code (in accumulator-passing style) only works through  
>> about
>> n=1300 for me.
>
> Though a more "functional approach" is to hide the helper function:
>
> def fib n
>   def fib_helper n, next_val, val
>     n < 1 ? val : fib_helper( n-1, next_val + val, next_val)
>   end
>   fib_helper( n, 1, 1)
> end
>
>
> Matt
>

Sadly, that doesn't really hide the helper function. fib_helper will  
be at the same scope as fib, Ruby doesn't currently do nested  
function definitions.