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
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