Hello Daniel,
Wednesday, December 21, 2005, 6:24:29 PM, you wrote:
DC> So I can have an IO bit (e.g. a do-block) that calls functions (which
DC> are purely functional code) but I can't have a function that executes
DC> any IO.
it's true
DC> For example, it is not possible to write a function "my_read_file" that
DC> could work like this:
DC> my_data = my_read_file("my_file.txt")
DC> Correct? Otherwise this would be a function that is not referentially
DC> transparent.
you are right. type "IO a", after all, stands for "RealWorld ->
(a,RealWorld)", i.e. it gets RealWorld as parameter and returns,
besides value of type "a", a new RealWorld state. the function which
type don't ended with "IO a", just can't receive or return value of
type RealWorld, so there is just no way to check something outside or
return new state of the outer world
--
Best regards,
Bulat mailto:[EMAIL PROTECTED]
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