29 lines
808 B
Factor
29 lines
808 B
Factor
! Rewritten by Matthew Willis, July 2006
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! Copyright (C) 2004 Chris Double.
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! See http://factorcode.org/license.txt for BSD license.
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USING: lazy-lists math kernel sequences test ;
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IN: lazy-examples
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: naturals 0 lfrom ;
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: positives 1 lfrom ;
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: evens 0 [ 2 + ] lfrom-by ;
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: odds 1 lfrom [ 2 mod 1 = ] lsubset ;
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: powers-of-2 1 [ 2 * ] lfrom-by ;
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: ones 1 [ ] lfrom-by ;
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: squares naturals [ dup * ] lmap ;
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: first-five-squares 5 squares ltake list>array ;
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: divisible-by? ( a b -- bool )
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#! Return true if a is divisible by b
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mod 0 = ;
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: filter-multiples ( n list -- list )
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#! Given a lazy list of numbers, filter multiples of n
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swap [ divisible-by? not ] curry lsubset ;
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! : primes ( -- list )
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! 2 lfrom [ filter-multiples ] lapply ;
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! : first-ten-primes 10 primes ltake list>array ;
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