Might better ways, but the following work:
length [c | x <- [1..100], let c = chain x , length c > 15]
length [c | x <- [1..100], c <- [chain x] , length c > 15]
On Wed, Feb 16, 2011 at 9:19 AM, Tako Schotanus
Hello,
I was going through some of the tuturials and trying out different (syntactic) alternatives to the given solutions and I I got to this line:
*length [chain x | x <- [1..100] , length (chain x) > 15]*
Now, there's nothing wrong with it, it works of course. But the application of chain x is repeated twice and I wondered if there was a way for a guard in a list comprehension to refer to the item being produced?
Like this for example (invented syntax):
*length [@c(chain x) | x <- [1..100] , length c > 15]*
NB: Just to make clear, I'm not asking if there is an alternative way of preventing the repetition, of course there is, I'm just wondering about this very specific case within list comprehensions.
-Tako
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