From: ptkwt@... (Phil Tomson)
Date: 2005-03-27T04:19:47+09:00
Subject: Re: Evaluator for a mini-Ruby in Haskell

In article <3alo9bF6d2vo8U1@individual.net>,
Robert Klemme <bob.news@gmx.net> wrote:
>
>
>I'm surprised about "retry", too.  His analysis sounds all very resonable - 
>only that "break" does not work for me but "return" does:
>
>>> def my_while(cond)
>>>   break unless cond
>>>   yield
>>>   retry
>>> end
>=> nil
>>> i = 0
>=> 0
>>> my_while i < 10 do
>?>   puts i
>>>   i += 1
>>> end
>0
>1
>2
>3
>4
>5
>6
>7
>8
>9
>LocalJumpError: unexpected break
>        from (irb):2:in `my_while'
>        from (irb):7


Hmmm...  break works find for me in 1.8.2.  Time to upgrade?


>
>Btw, can anybody think of a way to make my_while return the result of the 
>last block evaluation?  It seems impossible because the return occurs before 
>the yield...
>


How about:

  def my_while(cond)
    return @ret unless cond
    @ret = yield
    retry
  end


Phil