Robin Green wrote:

On Mon, 12 Jan 2009 21:04:35 +0100 (CET) Henning Thielemann wrote:

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On Mon, 12 Jan 2009, Andrew Coppin wrote:

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convert b = unfoldr (\n -> if n > 0 then Just (n `mod` b, n `div` b) else Nothing)

I have the nice function 'toMaybe' which simplifies this to: unfoldr (\n -> toMaybe (n>0) (n `mod` b, n `div` b))

I would use the more general idiom:

unfoldr (\n -> guard (n > 0) >> return (n `mod` b, n `div` b)

One of the wonderful things about Haskell is that almost any time anybody posts code, at least one person will think up an alternative but equivilent way of achieving the same goal - sometimes by radically different steps. Maybe we should have a name for this effect?

Colin Adams wrote:

2009/1/13 Andrew Coppin :

...

One of the wonderful things about Haskell is that almost any time anybody posts code, at least one person will think up an alternative but equivilent way of achieving the same goal - sometimes by radically different steps.

Maybe we should have a name for this effect?

Confusion.

This is a worthy addition to the Humour page, IMHO... :-D

"Colin Adams" writes:

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One of the wonderful things about Haskell is that almost any time anybody posts code, at least one person will think up an alternative but equivilent way of achieving the same goal - sometimes by radically different steps.

...

Maybe we should have a name for this effect?

Confusion.

Golfusion? -k -- If I haven't seen further, it is by standing in the footprints of giants

Hi

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convert b 0 = [] convert b n = n `mod` b : convert b (n `div` b)

convert b = unfoldr (\n -> if n > 0 then Just (n `mod` b, n `div` b) else Nothing)

To my untrained eyes the second looks more complex... It can't be implemented in the HLint list recursion functions I've got at the moment since they first search for a pattern-match on []/(:) on the left to start the process, but maybe one day.

I have the nice function 'toMaybe' which simplifies this to: unfoldr (\n -> toMaybe (n>0) (n `mod` b, n `div` b))

Maybe HLint can also suggest non-base functions? ;-)

Yes, sure - but not by default. See http://code.google.com/p/ndmitchell/issues/detail?id=126 The idea is that if someone wants to maintain a separate Hints file, say HackageHints.hs, then an individual user can decide to add import HackageHints to their Hints.hs and use the additional hints, which may require arbitrary Haskell libraries. Thanks Neil