Manual page for hashtable-copy(3scm)

hashtable-copy - copy a hashtable

LIBRARY

(import (rnrs))                     ;R6RS
(import (rnrs hashtables))          ;R6RS

SYNOPSIS

(hashtable-copy hashtable)
(hashtable-copy hashtable mutable)

DESCRIPTION

Returns a copy of hashtable.

If the mutable argument is provided and is true, the returned hashtable is mutable; otherwise it is immutable.

RETURN VALUES

Returns a single value; a hashtable.

EXAMPLES

(define (alist->eqv-hashtable alist)
  (let ((ht (make-eqv-hashtable)))
    (do ((alist alist (cdr alist)))
        ((null? alist)
         (hashtable-copy ht))
      (hashtable-set! ht (caar alist) (cdar alist)))))

(hashtable-entries
 (alist->eqv-hashtable '((0 . zero) (1 . one) (2 . three))))
    => #(0 1 2)
       #(zero one three)

RATIONALE

Allowing the hashtable to be immutable allows implementations to create an optimized representation for the hashtable.

COMPATIBILITY

This procedure is unique to R6RS.

ERRORS

This procedure can raise exceptions with the following condition types:

&assertion (R6RS): The wrong number of arguments was passed or an argument was outside its domain. In particular, hashtable must be a hashtable.

STANDARDS

R6RS

HISTORY

This procedure first appeared in R6RS, but a similar procedure was also present in SRFI-69.

AUTHORS

This page is part of the scheme-manpages project. It includes materials from the RnRS documents. More information can be found at https://github.com/schemedoc/manpages/.

Markup created by unroff 1.0sc, March 04, 2023.