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From: "B. Pym" <Nobody447095@here-nor-there.org>
Newsgroups: comp.lang.lisp
Subject: Re: Please critique my code
Date: Tue, 16 Jul 2024 03:00:37 -0000 (UTC)
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Pascal J. Bourguignon wrote:

> (defun hashtable-to-array (hashtable)
>   "Convert a hash table to a 2d array.
> Keys are stored in the column 0, and values in the column 1"
>   (let ((array (make-array (list (hash-table-count hashtable) 2)))
>         (i 0))
>      (maphash (lambda (k v)
>                   (setf (aref array i 0) k
>                         (aref array i 1) v)
>                   (incf i))
>               hashtable)
>      array))
> 
> C/USER[35]> (HASHTABLE-TO-ARRAY #S(HASH-TABLE :test eql (one . 1) (two . 2) (thr
> ee . 3)))
> #2A((THREE 3) (TWO 2) (ONE 1))

Gauche Scheme

(use gauche.array)
(use gauche.collection)
(use util.match)

(define (hashtable->array ht)
  (rlet1 ary (make-array (shape  0 (size-of ht)  0 2))
    (for-each
      (match-lambda* [((k . v) i)
        (array-set! ary i 0 k)
        (array-set! ary i 1 v)])
      ht
      (lrange 0))))

(pretty-print-array
  (hashtable->array 
    (hash-table 'eqv? '(one . 1) '(two . 2) '(three . 3))))

#,(<array> (0 3 0 2)
three 3
  two 2
  one 1
  )