[Haskell-cafe] Re: Strange typing?

[Ozgur Akgun]

Thank you all very much for the pointers.

Best,

On 22 March 2010 09:32, Gleb Alexeyev <gleb.alexeev at gmail.com> wrote:

> Ozgur Akgun wrote:
>
>> Is there any way to limit a functions type, not by a data type but by a
>> group of constructors of a data type? If not, what would be the *right*
>> thing to do to achieve this level of type safety?
>>
>> data DT1 = X | Y | Z
>> data DT2 = A | B | C | D
>>
>>
>> func1 :: DT1 -> DT2 -- instead of this
>> func1' :: (X|Y) -> (B|C) -- i want sth. like this. (| means or)
>>
>>  OCaml has a feature called 'polymorphic variants' that allows exactly
> this. You may want to google 'polymorphic variants in haskell'.
>
>
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-- 
Ozgur Akgun
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