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 _______________________________________________ Beginners mailing list Beginners@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
-- Regards Sumit Sahrawat