[Haskell-beginners] Re: Beginners Digest, Vol 27, Issue 57

28 Sep 2010

      Ahaaa, the heureka moment. Stupid me, I should have tried :t null
Thanks Brent!

On 9/27/2010 6:00 PM, beginners-request@haskell.org wrote:
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Today's Topics:
1. Re:  matching the output of a standard function	to my
       function definition (non-exhaustive pattern problem) (Brent Yorgey)
----------------------------------------------------------------------
Message: 1
Date: Mon, 27 Sep 2010 12:21:08 -0400
From: Brent Yorgey
Subject: Re: [Haskell-beginners] matching the output of a standard
  function	to my function definition (non-exhaustive pattern problem)
To: beginners@haskell.org
Message-ID:<20100927162108.GA5408@seas.upenn.edu>
Content-Type: text/plain; charset=us-ascii
On Mon, Sep 27, 2010 at 06:15:22PM +0200, Martin Tomko wrote:
...
Dear Daniel
that worked perfectly, thanks for the suggestion!
One more question: how do you use null to check for empty lists?
something like [] == null did not work ... just chekcing, I got my
orignal code to work, thanks again!
Martin
When in doubt, consult the types!
null :: [a] ->  Bool
That is, null is a function for testing lists to see whether they are
empty.  So rather than 'list == null' you write 'null list'.
-Brent
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