Lars Lundgren writes:

On 26 Sep 2002, Yoann Padioleau wrote:

...

Koen Claessen writes:

i find your idea very good. indeed for the library GetOpt, the argument of a program never change so it make sense to make this library without using IO monad, same for argv and for the enviroment.

...

for openFile it seems harder, it would require to have a lock on the file to be sure that no one modify the file, same for a webpage.

No, not at all. All that is required is to make sure all calls to openFile f returns the same string, i.e the contents of the file when it was read the first time.

yes you are right. but it requires to change the name of the function to have Once appended to it. so in the Prelude, we should have 2 version of the same kind of fonction, one pure such as readFileOnce with a cool type, and one such as readFile with an Io type. Sounds good idea to me, cos many programs require just to read a file one time. i dont know if practically it is useful. after all we can do all the IO stuff in the main, and then continue in a pure world. dont know if it is useful to read a file in the middle of a pure function.

/Lars L

-- Yoann Padioleau, INSA de Rennes, France, Opinions expressed here are only mine. Je n'écris qu'à titre personnel. **____ Get Free. Be Smart. Simply use Linux and Free Software. ____**