14 lines
375 B
Factor
14 lines
375 B
Factor
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! Copyright (C) 2012 John Benediktsson
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! See http://factorcode.org/license.txt for BSD license
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USING: combinators.short-circuit grouping kernel math
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math.primes sequences ;
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IN: math.primes.twins
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: twin-primes-upto ( n -- seq )
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primes-upto 2 <clumps> [ first2 - abs 2 = ] filter ;
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: twin-primes? ( x y -- ? )
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{ [ - abs 2 = ] [ nip prime? ] [ drop prime? ] } 2&& ;
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