[Haskell-beginners] Equivalent of IO Monad in other functional languages?

[Sumit Sahrawat, Maths & Computing, IIT (BHU)]

Haskell is impure only when you use the unsafe* functions (atleast that's
how I understand purity).

My understanding is that a language is impure if it allows one to write
arbitrary IO within a function and still give it a proper (mathematical)
function type. In other words impurity arises only if you can unwrap the IO
monad (which is what the unsafe functions do).

The two examples you give above are pure under such a perspective, but I
might be wrong.

On 15 March 2015 at 23:19, <amindfv at gmail.com> wrote:

> 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 at 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 at 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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-- 
Regards

Sumit Sahrawat
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