Hello,
First let's see how 'partition' from SRFI-1 does on allocation:
(import (except (rnrs) partition)
(only (srfi :1) iota partition)
(only (ikarus) time))
(let ((data (iota 1000)))
(time (partition odd? data)))
~ # ikarus --r6rs-script /scratch/_partition-srfi-1-a.sps
running stats for (partition odd? data):
no collections
0 ms elapsed cpu time, including 0 ms collecting
0 ms elapsed real time, including 0 ms collecting
40008 bytes allocated
The (rnrs) library also provides a 'partition':
(import (rnrs)
(only (srfi :1) iota)
(only (ikarus) time))
(let ((data (iota 1000)))
(time (partition odd? data)))
~ # ikarus --r6rs-script /scratch/_partition-rnrs-a.sps
running stats for (partition odd? data):
no collections
0 ms elapsed cpu time, including 0 ms collecting
0 ms elapsed real time, including 0 ms collecting
28016 bytes allocated
Much better.
I was messing around with another version of 'partition'. This one takes
a third parameter instead of returning two values. You can emulate the
RNRS/SRFI version simply by passing 'values' as the third argument.
Let's see how it does:
(import (except (rnrs) partition)
(only (srfi :1) iota)
(only (ikarus) time))
(define (partition fun lis c)
(cond ( (null? lis) (c '() '()) )
( (fun (car lis))
(partition fun
(cdr lis)
(lambda (a b)
(c (cons (car lis) a)
b))) )
( else
(partition fun
(cdr lis)
(lambda (a b)
(c a
(cons (car lis) b)))) )))
(let ((data (iota 1000)))
(time (partition odd? data values)))
~ # ikarus --r6rs-script /scratch/_partition-a.sps
running stats for (partition odd? data values):
no collections
0 ms elapsed cpu time, including 0 ms collecting
0 ms elapsed real time, including 0 ms collecting
24016 bytes allocated
I.e. it does the least allocation. This was a surprise.
Ed
