[Haskell-cafe] Maybe a, The Rationale

[PR Stanley]

>>>>        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
>>>functions.
>>>Looking up a map will only sometimes find a value, so we either
>>>return
>>>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
>really difficult?


         Paul: Hmm, I'm not quite sure what you're driving at.

                 Cheers, Paul