On Thu, Dec 10, 2009 at 12:01 PM, John D. Earle
This is a matter that I genuinely at the present time do not grasp and I am hoping that some of you who are more familiar with the Haskell language may be able to help enlighten me. I feel the question to be an important one. What material benefit does Haskell derive from being a "pure" functional language as opposed to an impure one? Please provide examples as I require instruction.
The following is what I believe to be true at the present time. It seems to be that the decision was made because it was a matter of taste under the belief that computer scientists can and often are superstitious and their superstitions can and often do materially interfere with progress. What I am saying is that at the present time perhaps due to my ignorance I am unfamiliar with how this benefits the language in a material sense. It appears to be a philosophical matter, a matter of identity, what Haskell stands for.
The sort of decision that Apple computer and Microsoft made not to go down the POSIX road seems relevant. Historically, Apple did not embrace POSIX. Windows continues to stand for Windows, that is the graphical user interface.
As I understand it it all started with laziness. I don't know if laziness is impossible without purity, but talks and papers tend to say something like "laziness has kept Haskell pure". /M -- Magnus Therning (OpenPGP: 0xAB4DFBA4) magnus＠therning．org Jabber: magnus＠therning．org http://therning.org/magnus identi.ca|twitter: magthe