Last change
on this file since 212 was 2, checked in by Rick van der Zwet, 15 years ago |
Initial import of data of old repository ('data') worth keeping (e.g. tracking
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Property svn:executable
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File size:
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[2] | 1 | #!/usr/bin/env guile -s
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| 2 | !#
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| 3 |
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| 4 |
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| 5 | ; * Rick van der Zwet
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| 6 | ; * 0433373
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| 7 | ; * Scheme programming assigment 1a
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| 8 | ; * Licence: BSD
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| 9 | ; * $Id: exercise1a.scm 374 2007-12-10 20:18:45Z rick $
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| 10 |
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| 11 | ; replace find and replace
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| 12 | (define sub_atom
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| 13 | (lambda (atom sub)
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| 14 | ;write down replacement else procede to next of the list
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| 15 | (cond
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| 16 | ((null? sub) atom)
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| 17 | ((eq? (caar sub) atom) (cadar sub))
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| 18 | (else (sub_atom atom (cdr sub)))
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| 19 | )
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| 20 | )
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| 21 | )
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| 22 |
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| 23 | (define substitute
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| 24 | (lambda (lijst sub)
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| 25 | ;if element a return sub if found else element using adding pair (a
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| 26 | ; a) to replace sub
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| 27 | (if (list? lijst)
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| 28 | ;if list and both head and tail recurse both
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| 29 | ;else recurse single
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| 30 | (if (null? (cdr lijst))
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| 31 | (list (substitute (car lijst) sub))
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| 32 | (cons (substitute (car lijst) sub)
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| 33 | (substitute (cdr lijst) sub))
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| 34 | )
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| 35 | ; try to do the replacement
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| 36 | (sub_atom lijst sub)
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| 37 | )
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| 38 | )
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| 39 | )
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| 40 |
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| 41 |
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| 42 |
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| 43 |
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| 44 | (display
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| 45 | (equal?
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| 46 | (substitute
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| 47 | '((a (b c) d) a (f b))
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| 48 | '((a z) (b y))
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| 49 | )
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| 50 | '((z (y c) d) z (f y))
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| 51 | )
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| 52 | )
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