Re: 99 bottles of beer

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Subject: Re: 99 bottles of beer
From: Abel Braaksma <abel.online@xxxxxxxxx>
Date: Mon, 05 Feb 2007 21:10:15 +0100

Andrew Welch wrote:

Nice! However a couple of small problems:

2 bottles of beer on the wall.
2 bottles of beer.
Take one down, pass it around
1 bottles of beer on the wall.
     ^^^^^^^

1 bottle of beer on the wall.
1 bottle of beer.
Take one down, pass it around
0 bottle of beer on the wall.
      ^^^^^^^^

You just need to modify it slightly:

Thanks for the correction. But now we have duplicated logic (the cast + ends-with), which some consider bad programming practice. Here's an update that does not duplicate the logic, removes the nested for (better: it shows a way of shortcutting nested loops with the comma operator), corrects my error and is much less readable (which was not on purpose, btw).

for $i in reverse(1 to 99),
   $j in (1 to 3)

return concat ($i - xs:integer($j mod 3 = 0), ' bottle', ('s')[not($i * 3 - $j = (1 to 3))], ' of beer', (' on the wall.', '.
Take one down, pass it around', ' on the wall.
' )[$j]

(I like the idea of using the predicate instead of if...then...else)

As a tutorial it suits well for explaining why:

('s')[$i * 3 - $j != (1 to 3)]

yields exactly the same result as:

('s')[$i * 3 - $j = (1 to 3)]

which is quite counter-intuitive (IIRC, for a '!=' to return false, none from the left must be the same as any from the right; to be true, only one item needs to be unequal. This is not backed up by the example above, but I am sure I am overlooking something. Moreover, I found that (1 to 2) != 10 returns false, and (1,2) != 10 returns true.... I am really missing something here, this must be a faq somewhere :S ).


Cheers,
-- Abel Braaksma
  http://www.nuntia.nl

Current Thread
99 bottles of beer Andrew Welch - 5 Feb 2007 11:30:18 -0000 Abel Braaksma - 5 Feb 2007 12:48:41 -0000 Andrew Welch - 5 Feb 2007 13:05:25 -0000 Abel Braaksma - 5 Feb 2007 20:11:56 -0000 <= Andrew Welch - 5 Feb 2007 20:38:20 -0000 Michael Kay - 5 Feb 2007 22:57:22 -0000 Abel Braaksma - 5 Feb 2007 23:25:26 -0000 Michael Kay - 5 Feb 2007 22:56:47 -0000

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