69 lines
1.8 KiB
Scheme
69 lines
1.8 KiB
Scheme
;;
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;; util-list.scm
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;;
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;; Various utilities so that no external libraries are needed.
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;;
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;; ISC License
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;;
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;; Copyright 2023 Brmlab, z.s.
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;; Dominik Pantůček <dominik.pantucek@trustica.cz>
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;;
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;; Permission to use, copy, modify, and/or distribute this software
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;; for any purpose with or without fee is hereby granted, provided
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;; that the above copyright notice and this permission notice appear
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;; in all copies.
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;;
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;; THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
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;; WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
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;; WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
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;; AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
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;; CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
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;; OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
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;; NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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;; CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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;;
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(declare (unit util-list))
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(import duck)
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(module*
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util-list
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#:doc ("This module implements basic list functionality which is common in
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most scheme implementations.")
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(
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filter
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util-list-tests!
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)
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(import scheme
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(chicken base)
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(chicken io)
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(chicken process)
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testing)
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(define/doc (filter pred? lst)
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("* ```pred?``` - procedure accepting any value and returning #t or #f
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* ```lst``` - list to be filtered
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Returns a list containing only elements matching given ```pred?```
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predicate.")
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(let loop ((lst lst)
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(res '()))
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(if (null? lst)
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(reverse res)
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(if (pred? (car lst))
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(loop (cdr lst)
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(cons (car lst) res))
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(loop (cdr lst)
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res)))))
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;; Performs utils module self-tests.
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(define (util-list-tests!)
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(run-tests
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util-list
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(test-equal? filter (filter odd? '(1 2 3 4)) '(1 3))
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(test-equal? filter (filter odd? '(2 4)) '())
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))
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)
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