blob: 6b89708cefccca369a9f5ccdd9b67e70420f072e (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
|
;;; vector.el --- Working with Elisp's Vector data type -*- lexical-binding: t -*-
;; Author: William Carroll <wpcarro@gmail.com>
;; Version: 0.0.1
;; Package-Requires: ((emacs "25.1"))
;;; Commentary:
;; It might be best to think of Elisp vectors as tuples in languages like
;; Haskell or Erlang.
;;
;; Not surprisingly, this API is modelled after Elixir's Tuple API.
;;
;; Some Elisp trivia:
;; - "Array": Usually means vector or string.
;; - "Sequence": Usually means list or "array" (see above).
;;
;; It might be a good idea to think of Array and Sequence as typeclasses in
;; Elisp. This is perhaps more similar to Elixir's notion of the Enum protocol.
;;
;; Intentionally not supporting a to-list function, because tuples can contain
;; heterogenous types whereas lists should contain homogenous types.
;;; Code:
;; TODO: Consider supporting an alias named tuple for vector.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Library
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defconst vector-enable-tests? t
"When t, run the tests defined herein.")
;; TODO: Consider labelling variadic functions like `vector-concat*'
;; vs. `vector-concat'.
(defun vector-concat (&rest args)
"Return a new vector composed of all vectors in `ARGS'."
(apply #'vconcat args))
;; TODO: Here's a sketch of a protocol macro being consumed.
;; (definstance monoid vector
;; :empty (lambda () []))
(defun vector-prepend (x xs)
"Add `X' to the beginning of `XS'."
(vector-concat `[,x] xs))
(defun vector-append (x xs)
"Add `X' to the end of `XS'."
(vector-concat xs `[,x]))
(defun vector-get (i xs)
"Return the value in `XS' at index, `I'."
(aref xs i))
(defun vector-set (i v xs)
"Set index `I' to value `V' in `XS'.
Returns a copy of `XS' with the updates."
(let ((copy (vconcat [] xs)))
(aset copy i v)
copy))
(defun vector-set! (i v xs)
"Set index `I' to value `V' in `XS'.
This function mutates XS."
(aset xs i v))
(when vector-enable-tests?
(let ((xs [1 2 3])
(ys [1 2 3]))
(prelude-assert (= 1 (vector-get 0 ys)))
(vector-set 0 4 ys)
(prelude-assert (= 1 (vector-get 0 ys)))
(prelude-assert (= 1 (vector-get 0 xs)))
(vector-set! 0 4 xs)
(prelude-assert (= 4 (vector-get 0 xs)))))
;; TODO: Decide between "remove" and "delete" as the appropriate verbs.
;; TODO: Implement this.
;; (defun vector/delete (i xs)
;; "Remove the element at `I' in `XS'.")
(provide 'vector)
;;; vector.el ends here
|
