From dac20e1e41bbe12b178870d368e7fc56fc12815b Mon Sep 17 00:00:00 2001
From: Camil Staps
Date: Tue, 11 Oct 2016 12:29:53 +0000
Subject: Added simple examples

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 fsieve.icl | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 fsieve.icl

(limited to 'fsieve.icl')

diff --git a/fsieve.icl b/fsieve.icl
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+module fsieve
+
+/*
+The Fast Sieve of Eratosthenes.
+
+A sequential and optimized version of the sieve of Eratosthenes.
+The program calculates a list of the first NrOfPrime primes.
+The result of the program is the NrOfPrimes'th prime.
+
+Strictness annotations have been added because the strictness analyser
+is not able to deduce all strictness information. Removal of these !'s
+will make the program about 20% slower.
+
+On a machine without a math coprocessor the execution of this
+program might take a (very) long time. Set NrOfPrimes to a smaller value.
+*/
+
+import StdClass; // RWS
+import StdInt, StdReal
+     
+NrOfPrimes :== 10
+	
+//	The sieve algorithm: generate an infinite list of all primes.
+
+Primes::[Int]
+Primes = pr where pr = [5 : Sieve 7 4 pr]
+
+Sieve::Int !Int [Int] -> [Int]
+Sieve g i prs
+	| IsPrime prs g (toInt (sqrt (toReal g)))	=  [g : Sieve` g i prs]
+												=  Sieve (g + i) (6 - i) prs
+
+Sieve`::Int Int [Int] -> [Int]
+Sieve` g i prs =  Sieve (g + i) (6 - i) prs
+
+IsPrime::[Int] !Int Int -> Bool
+IsPrime [f:r] pr bd | f>bd 			=  True
+					| pr rem f==0	=  False
+									=  IsPrime r pr bd
+								  
+//	Select is used to get the NrOfPrimes'th prime from the infinite list.
+
+Select::[x] Int -> x
+Select [f:r] 1 =  f
+Select [f:r] n =  Select r (n - 1)
+
+
+/*	The Start rule: Select the NrOfPrimes'th prime from the list of primes
+	generated by Primes.
+*/
+
+Start::Int
+Start = Select [2, 3 : Primes] NrOfPrimes
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