From: Morton Goldberg <m_goldberg@...>
Date: 2007-11-12T12:26:52+09:00
Subject: Re: The Man or Boy Recursion Test

On Nov 11, 2007, at 8:46 PM, Tim Hunter wrote:

> Morton Goldberg wrote:
>> On Nov 11, 2007, at 6:42 PM, Tim Hunter wrote:
>>> Ummmm...before I wrote C I wrote PL/I. Not a lot, but enough to  
>>> be able to use the PL/I version of the Man or Boy test to figure  
>>> out how to code the Ruby version.
>> Interesting. I used your Ruby version to figure out how to code it  
>> in Mathematica. I was able to make a fairly direct translation.
>> <code>
>> $RecursionLimit = 1665; (* anything less fails for k0 = 10 *)
>> a[k0_, x1_, x2_, x3_, x4_, x5_] := Module[{k, b },
>>   k = k0;
>>   b = (k--; a[k, b, x1, x2, x3, x4]) &;
>>   If[k <= 0, x4[] + x5[], b[]]]
>> a[10, 1 &, -1 &, -1 &, 1 &, 0 &] (* => -67 *)
>> </code>
>> Note how compact the Mathematica notation for the thunks is.
>> Regards, Morton
>
> Another one for Wikipedia.

I've posted it there. I like the Smalltalk example also -- very  
concise yet still readable.

> I guess we owe Werner (the OP) a big "thanks" for introducing such  
> an interesting thread. Thanks, Werner!

Indeed.

Regards, Morton