[Haskell-cafe] Maybe a, The Rationale
prstanley at ntlworld.com
Sat May 10 19:10:45 EDT 2008
>>>> Paul: Hi folks
>>>> data Maybe a = Nothing | Just a
>>>> What is the underlying rationale for the Maybe data type?
>>>>is it the
>>>>safe style of programming it encourages/
>>>>Something tells me this is going to start a lengthy discussion. :-)
>>> Bob: Pure and simple -- it allows you to represent partial
>>>Looking up a map will only sometimes find a value, so we either
>>>Nothing, or Just that value.
>> Paul: Would yu like to demonstrate this in an example?
>Um, I was encountering and recognizing times when I really needed an
>out-of-band "null", and the pain of representing such in C, shortly
>after I started serious programming in C (call it 1984-5). Is this
Paul: Hmm, I'm not quite sure what you're driving at.
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