C is "pure" too. The statement puts ("hello"); is a "pure" value of type int.

dllthomas · on May 7, 2015

No, that statement evaluates to a pure value of type int. In the process, it does something else as well that effects the visible behavior of the program.

The C equivalent of

    putStrLn "hello"

is probably actually

    void putsHello(void) {
        puts("hello");
    }

Unfortunately, function definitions aren't something you can really manipulate at runtime in C.

wz1000 · on May 7, 2015

Here is a comment I wrote about the same issue some time ago:

https://news.ycombinator.com/item?id=9085403

Haskell IO is severely misunderstood.