From that perspective isn't every language pure? Haskell's still got "randomIO" and "print <=< readMVar"

Tom

El Mar 15, 2015, a las 13:15, "Sumit Sahrawat, Maths & Computing, IIT (BHU)" <sumit.sahrawat.apm13@iitbhu.ac.in> escribió:

Hello Simon,

If you changed your perspective, you would realize that all functions in haskell are pure.

A function is pure if it returns the same output if given the same input. Every monadic function (including functions returning IO) is also pure.

For example,

    putStrLn :: String -> IO ()

    -- A function that takes a string, and returns an impure computation

    -- which, when executed will print the given String.

For any string, putStrLn applied to that same string always describes the same impure computation, thus the function is actually pure.

I am not familiar with any other functional language, but there are not many purely functional ones out there [1].

I guess the impure ones get around this issue by giving in to impurity, but I'm not sure.

I'll be interested in hearing more about the other languages too.

[1] : http://en.wikipedia.org/wiki/List_of_programming_languages_by_type#Pure

On 15 March 2015 at 22:25, Marcin Mrotek <marcin.jan.mrotek@gmail.com> wrote:

Hello,

F* uses a somewhat similar approach: https://fstar-lang.org/tutorial/
(section 2, Types and Effects)

Best regards,
Marcin Mrotek

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Regards

Sumit Sahrawat

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