list-copy -- r7rs Definition

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Kind

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procedure;

Implemented by

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• list-copy (from vonuvoli);

Procedure signature

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Procedure variants:

• ((null) -> (null))
  • input: a value of type null;
  • output: a value of type null;
• ((list-not-circular) -> (list-not-circular))
  • input: a value of type list-not-circular;
  • output: a value of type list-not-circular;
• ((list-circular) -> (exception))
  • input: a value of type list-circular;
  • output: a value of type exception;
• (((a any)) -> ((a any)))
  • input: a of type any;
  • output: a of type any;

Exports

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• scheme:base -- (scheme base);

Exports recursive

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• scheme -- (scheme);

Description

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(list-copy obj)

Returns a newly allocated copy of the given obj if it is a list. Only the pairs themselves are copied; the cars of the result are the same (in the sense of eqv?) as the cars of list. If obj is an improper list, so is the result, and the final cdrs are the same in the sense of eqv?. An obj which is not a list is returned unchanged. It is an error if obj is a circular list.

(define a '(1 8 2 8))     ; a may be immutable
(define b (list-copy a))
(set-car! b 3)            ; b is mutable
b  ===>  (3 8 2 8)
a  ===>  (1 8 2 8)

---

The text herein was sourced and adapted as described in the "R7RS attribution of various text snippets" appendix.

Referenced-types

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• null;
• list-not-circular;
• list-circular;
• exception;
• any;