Generator (computer programming): Difference between revisions

Revision as of 09:26, 23 November 2011

Revision as of 09:32, 23 November 2011

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which re-fetches values agreable with a predicate, and stops requesting new values as soon as a non-agreable one is encountered. The storage access is used as a universal mediator in Haskell. List comprehensions can be freely used:

<source lang="haskell">

countfromBy (n,x) = n : countfromBy (n+x,x)

primes = 2 : 3 : [n | n <- [5,7..], all ((/=0).(rem n)) $ takeWhile ((<=n).(^2)) $ tail primes]

primes = 2 : 3 : [n | n <- countfromBy (5,2)

primes = 2 : 3 : [n | n <- [5,7..] , all ((/=0).(rem n)) $ takeWhile ((<=n).(^2)) $ tail primes]

test2 = mapM_ print $ takeWhile (<= 20) [x*x | x <- countfrom 10]