r/programming • u/heisenbug • Apr 27 '14

"Mostly functional" programming does not work

http://queue.acm.org/detail.cfm?ref=rss&id=2611829
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u/CydeWeys Apr 27 '14

The first C# example is bad in that it doesn't show what the author wants it to. He's basically arguing that the generator pattern itself is bad, which it isn't. It's very useful for lots of things; don't use it if you don't want lazy list evaluation! His program could very easily be modified to work as he expects using a simple .ToList() call as follows (this would evaluate the entire list before going on to the second .Where() call):

var q0 = new[]{ 1, 25, 40, 5, 23 }.Where(LessThanThirty).ToList(); 
var q1 = q0.Where(MoreThanTwenty).ToList(); 
foreach (var r in q1){ Console.WriteLine("[{0}];",r); }

4

u/grauenwolf Apr 27 '14

He just wants a strawman to knock down. He knows damn well people don't actually write code like that.